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/wp-includes/ -> meta.php (source)

   1  <?php
   2  /**
   3   * Core Metadata API
   4   *
   5   * Functions for retrieving and manipulating metadata of various WordPress object types. Metadata
   6   * for an object is a represented by a simple key-value pair. Objects may contain multiple
   7   * metadata entries that share the same key and differ only in their value.
   8   *
   9   * @package WordPress
  10   * @subpackage Meta
  11   */
  12  
  13  require  ABSPATH . WPINC . '/class-wp-metadata-lazyloader.php';
  14  
  15  /**
  16   * Adds metadata for the specified object.
  17   *
  18   * @since 2.9.0
  19   *
  20   * @global wpdb $wpdb WordPress database abstraction object.
  21   *
  22   * @param string $meta_type  Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
  23   *                           or any other object type with an associated meta table.
  24   * @param int    $object_id  ID of the object metadata is for.
  25   * @param string $meta_key   Metadata key.
  26   * @param mixed  $meta_value Metadata value. Must be serializable if non-scalar.
  27   * @param bool   $unique     Optional. Whether the specified metadata key should be unique for the object.
  28   *                           If true, and the object already has a value for the specified metadata key,
  29   *                           no change will be made. Default false.
  30   * @return int|false The meta ID on success, false on failure.
  31   */
  32  function add_metadata( $meta_type, $object_id, $meta_key, $meta_value, $unique = false ) {
  33      global $wpdb;
  34  
  35      if ( ! $meta_type || ! $meta_key || ! is_numeric( $object_id ) ) {
  36          return false;
  37      }
  38  
  39      $object_id = absint( $object_id );
  40      if ( ! $object_id ) {
  41          return false;
  42      }
  43  
  44      $table = _get_meta_table( $meta_type );
  45      if ( ! $table ) {
  46          return false;
  47      }
  48  
  49      $meta_subtype = get_object_subtype( $meta_type, $object_id );
  50  
  51      $column = sanitize_key( $meta_type . '_id' );
  52  
  53      // expected_slashed ($meta_key)
  54      $meta_key   = wp_unslash( $meta_key );
  55      $meta_value = wp_unslash( $meta_value );
  56      $meta_value = sanitize_meta( $meta_key, $meta_value, $meta_type, $meta_subtype );
  57  
  58      /**
  59       * Short-circuits adding metadata of a specific type.
  60       *
  61       * The dynamic portion of the hook name, `$meta_type`, refers to the meta object type
  62       * (post, comment, term, user, or any other type with an associated meta table).
  63       * Returning a non-null value will effectively short-circuit the function.
  64       *
  65       * Possible hook names include:
  66       *
  67       *  - `add_post_metadata`
  68       *  - `add_comment_metadata`
  69       *  - `add_term_metadata`
  70       *  - `add_user_metadata`
  71       *
  72       * @since 3.1.0
  73       *
  74       * @param null|bool $check      Whether to allow adding metadata for the given type.
  75       * @param int       $object_id  ID of the object metadata is for.
  76       * @param string    $meta_key   Metadata key.
  77       * @param mixed     $meta_value Metadata value. Must be serializable if non-scalar.
  78       * @param bool      $unique     Whether the specified meta key should be unique for the object.
  79       */
  80      $check = apply_filters( "add_{$meta_type}_metadata", null, $object_id, $meta_key, $meta_value, $unique );
  81      if ( null !== $check ) {
  82          return $check;
  83      }
  84  
  85      if ( $unique && $wpdb->get_var(
  86          $wpdb->prepare(
  87              "SELECT COUNT(*) FROM $table WHERE meta_key = %s AND $column = %d",
  88              $meta_key,
  89              $object_id
  90          )
  91      ) ) {
  92          return false;
  93      }
  94  
  95      $_meta_value = $meta_value;
  96      $meta_value  = maybe_serialize( $meta_value );
  97  
  98      /**
  99       * Fires immediately before meta of a specific type is added.
 100       *
 101       * The dynamic portion of the hook name, `$meta_type`, refers to the meta object type
 102       * (post, comment, term, user, or any other type with an associated meta table).
 103       *
 104       * Possible hook names include:
 105       *
 106       *  - `add_post_meta`
 107       *  - `add_comment_meta`
 108       *  - `add_term_meta`
 109       *  - `add_user_meta`
 110       *
 111       * @since 3.1.0
 112       *
 113       * @param int    $object_id   ID of the object metadata is for.
 114       * @param string $meta_key    Metadata key.
 115       * @param mixed  $_meta_value Metadata value.
 116       */
 117      do_action( "add_{$meta_type}_meta", $object_id, $meta_key, $_meta_value );
 118  
 119      $result = $wpdb->insert(
 120          $table,
 121          array(
 122              $column      => $object_id,
 123              'meta_key'   => $meta_key,
 124              'meta_value' => $meta_value,
 125          )
 126      );
 127  
 128      if ( ! $result ) {
 129          return false;
 130      }
 131  
 132      $mid = (int) $wpdb->insert_id;
 133  
 134      wp_cache_delete( $object_id, $meta_type . '_meta' );
 135  
 136      /**
 137       * Fires immediately after meta of a specific type is added.
 138       *
 139       * The dynamic portion of the hook name, `$meta_type`, refers to the meta object type
 140       * (post, comment, term, user, or any other type with an associated meta table).
 141       *
 142       * Possible hook names include:
 143       *
 144       *  - `added_post_meta`
 145       *  - `added_comment_meta`
 146       *  - `added_term_meta`
 147       *  - `added_user_meta`
 148       *
 149       * @since 2.9.0
 150       *
 151       * @param int    $mid         The meta ID after successful update.
 152       * @param int    $object_id   ID of the object metadata is for.
 153       * @param string $meta_key    Metadata key.
 154       * @param mixed  $_meta_value Metadata value.
 155       */
 156      do_action( "added_{$meta_type}_meta", $mid, $object_id, $meta_key, $_meta_value );
 157  
 158      return $mid;
 159  }
 160  
 161  /**
 162   * Updates metadata for the specified object. If no value already exists for the specified object
 163   * ID and metadata key, the metadata will be added.
 164   *
 165   * @since 2.9.0
 166   *
 167   * @global wpdb $wpdb WordPress database abstraction object.
 168   *
 169   * @param string $meta_type  Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
 170   *                           or any other object type with an associated meta table.
 171   * @param int    $object_id  ID of the object metadata is for.
 172   * @param string $meta_key   Metadata key.
 173   * @param mixed  $meta_value Metadata value. Must be serializable if non-scalar.
 174   * @param mixed  $prev_value Optional. Previous value to check before updating.
 175   *                           If specified, only update existing metadata entries with
 176   *                           this value. Otherwise, update all entries. Default empty string.
 177   * @return int|bool The new meta field ID if a field with the given key didn't exist
 178   *                  and was therefore added, true on successful update,
 179   *                  false on failure or if the value passed to the function
 180   *                  is the same as the one that is already in the database.
 181   */
 182  function update_metadata( $meta_type, $object_id, $meta_key, $meta_value, $prev_value = '' ) {
 183      global $wpdb;
 184  
 185      if ( ! $meta_type || ! $meta_key || ! is_numeric( $object_id ) ) {
 186          return false;
 187      }
 188  
 189      $object_id = absint( $object_id );
 190      if ( ! $object_id ) {
 191          return false;
 192      }
 193  
 194      $table = _get_meta_table( $meta_type );
 195      if ( ! $table ) {
 196          return false;
 197      }
 198  
 199      $meta_subtype = get_object_subtype( $meta_type, $object_id );
 200  
 201      $column    = sanitize_key( $meta_type . '_id' );
 202      $id_column = ( 'user' === $meta_type ) ? 'umeta_id' : 'meta_id';
 203  
 204      // expected_slashed ($meta_key)
 205      $raw_meta_key = $meta_key;
 206      $meta_key     = wp_unslash( $meta_key );
 207      $passed_value = $meta_value;
 208      $meta_value   = wp_unslash( $meta_value );
 209      $meta_value   = sanitize_meta( $meta_key, $meta_value, $meta_type, $meta_subtype );
 210  
 211      /**
 212       * Short-circuits updating metadata of a specific type.
 213       *
 214       * The dynamic portion of the hook name, `$meta_type`, refers to the meta object type
 215       * (post, comment, term, user, or any other type with an associated meta table).
 216       * Returning a non-null value will effectively short-circuit the function.
 217       *
 218       * Possible hook names include:
 219       *
 220       *  - `update_post_metadata`
 221       *  - `update_comment_metadata`
 222       *  - `update_term_metadata`
 223       *  - `update_user_metadata`
 224       *
 225       * @since 3.1.0
 226       *
 227       * @param null|bool $check      Whether to allow updating metadata for the given type.
 228       * @param int       $object_id  ID of the object metadata is for.
 229       * @param string    $meta_key   Metadata key.
 230       * @param mixed     $meta_value Metadata value. Must be serializable if non-scalar.
 231       * @param mixed     $prev_value Optional. Previous value to check before updating.
 232       *                              If specified, only update existing metadata entries with
 233       *                              this value. Otherwise, update all entries.
 234       */
 235      $check = apply_filters( "update_{$meta_type}_metadata", null, $object_id, $meta_key, $meta_value, $prev_value );
 236      if ( null !== $check ) {
 237          return (bool) $check;
 238      }
 239  
 240      // Compare existing value to new value if no prev value given and the key exists only once.
 241      if ( empty( $prev_value ) ) {
 242          $old_value = get_metadata_raw( $meta_type, $object_id, $meta_key );
 243          if ( is_countable( $old_value ) && count( $old_value ) === 1 ) {
 244              if ( $old_value[0] === $meta_value ) {
 245                  return false;
 246              }
 247          }
 248      }
 249  
 250      $meta_ids = $wpdb->get_col( $wpdb->prepare( "SELECT $id_column FROM $table WHERE meta_key = %s AND $column = %d", $meta_key, $object_id ) );
 251      if ( empty( $meta_ids ) ) {
 252          return add_metadata( $meta_type, $object_id, $raw_meta_key, $passed_value );
 253      }
 254  
 255      $_meta_value = $meta_value;
 256      $meta_value  = maybe_serialize( $meta_value );
 257  
 258      $data  = compact( 'meta_value' );
 259      $where = array(
 260          $column    => $object_id,
 261          'meta_key' => $meta_key,
 262      );
 263  
 264      if ( ! empty( $prev_value ) ) {
 265          $prev_value          = maybe_serialize( $prev_value );
 266          $where['meta_value'] = $prev_value;
 267      }
 268  
 269      foreach ( $meta_ids as $meta_id ) {
 270          /**
 271           * Fires immediately before updating metadata of a specific type.
 272           *
 273           * The dynamic portion of the hook name, `$meta_type`, refers to the meta object type
 274           * (post, comment, term, user, or any other type with an associated meta table).
 275           *
 276           * Possible hook names include:
 277           *
 278           *  - `update_post_meta`
 279           *  - `update_comment_meta`
 280           *  - `update_term_meta`
 281           *  - `update_user_meta`
 282           *
 283           * @since 2.9.0
 284           *
 285           * @param int    $meta_id     ID of the metadata entry to update.
 286           * @param int    $object_id   ID of the object metadata is for.
 287           * @param string $meta_key    Metadata key.
 288           * @param mixed  $_meta_value Metadata value.
 289           */
 290          do_action( "update_{$meta_type}_meta", $meta_id, $object_id, $meta_key, $_meta_value );
 291  
 292          if ( 'post' === $meta_type ) {
 293              /**
 294               * Fires immediately before updating a post's metadata.
 295               *
 296               * @since 2.9.0
 297               *
 298               * @param int    $meta_id    ID of metadata entry to update.
 299               * @param int    $object_id  Post ID.
 300               * @param string $meta_key   Metadata key.
 301               * @param mixed  $meta_value Metadata value. This will be a PHP-serialized string representation of the value
 302               *                           if the value is an array, an object, or itself a PHP-serialized string.
 303               */
 304              do_action( 'update_postmeta', $meta_id, $object_id, $meta_key, $meta_value );
 305          }
 306      }
 307  
 308      $result = $wpdb->update( $table, $data, $where );
 309      if ( ! $result ) {
 310          return false;
 311      }
 312  
 313      wp_cache_delete( $object_id, $meta_type . '_meta' );
 314  
 315      foreach ( $meta_ids as $meta_id ) {
 316          /**
 317           * Fires immediately after updating metadata of a specific type.
 318           *
 319           * The dynamic portion of the hook name, `$meta_type`, refers to the meta object type
 320           * (post, comment, term, user, or any other type with an associated meta table).
 321           *
 322           * Possible hook names include:
 323           *
 324           *  - `updated_post_meta`
 325           *  - `updated_comment_meta`
 326           *  - `updated_term_meta`
 327           *  - `updated_user_meta`
 328           *
 329           * @since 2.9.0
 330           *
 331           * @param int    $meta_id     ID of updated metadata entry.
 332           * @param int    $object_id   ID of the object metadata is for.
 333           * @param string $meta_key    Metadata key.
 334           * @param mixed  $_meta_value Metadata value.
 335           */
 336          do_action( "updated_{$meta_type}_meta", $meta_id, $object_id, $meta_key, $_meta_value );
 337  
 338          if ( 'post' === $meta_type ) {
 339              /**
 340               * Fires immediately after updating a post's metadata.
 341               *
 342               * @since 2.9.0
 343               *
 344               * @param int    $meta_id    ID of updated metadata entry.
 345               * @param int    $object_id  Post ID.
 346               * @param string $meta_key   Metadata key.
 347               * @param mixed  $meta_value Metadata value. This will be a PHP-serialized string representation of the value
 348               *                           if the value is an array, an object, or itself a PHP-serialized string.
 349               */
 350              do_action( 'updated_postmeta', $meta_id, $object_id, $meta_key, $meta_value );
 351          }
 352      }
 353  
 354      return true;
 355  }
 356  
 357  /**
 358   * Deletes metadata for the specified object.
 359   *
 360   * @since 2.9.0
 361   *
 362   * @global wpdb $wpdb WordPress database abstraction object.
 363   *
 364   * @param string $meta_type  Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
 365   *                           or any other object type with an associated meta table.
 366   * @param int    $object_id  ID of the object metadata is for.
 367   * @param string $meta_key   Metadata key.
 368   * @param mixed  $meta_value Optional. Metadata value. Must be serializable if non-scalar.
 369   *                           If specified, only delete metadata entries with this value.
 370   *                           Otherwise, delete all entries with the specified meta_key.
 371   *                           Pass `null`, `false`, or an empty string to skip this check.
 372   *                           (For backward compatibility, it is not possible to pass an empty string
 373   *                           to delete those entries with an empty string for a value.)
 374   *                           Default empty string.
 375   * @param bool   $delete_all Optional. If true, delete matching metadata entries for all objects,
 376   *                           ignoring the specified object_id. Otherwise, only delete
 377   *                           matching metadata entries for the specified object_id. Default false.
 378   * @return bool True on successful delete, false on failure.
 379   */
 380  function delete_metadata( $meta_type, $object_id, $meta_key, $meta_value = '', $delete_all = false ) {
 381      global $wpdb;
 382  
 383      if ( ! $meta_type || ! $meta_key || ! is_numeric( $object_id ) && ! $delete_all ) {
 384          return false;
 385      }
 386  
 387      $object_id = absint( $object_id );
 388      if ( ! $object_id && ! $delete_all ) {
 389          return false;
 390      }
 391  
 392      $table = _get_meta_table( $meta_type );
 393      if ( ! $table ) {
 394          return false;
 395      }
 396  
 397      $type_column = sanitize_key( $meta_type . '_id' );
 398      $id_column   = ( 'user' === $meta_type ) ? 'umeta_id' : 'meta_id';
 399  
 400      // expected_slashed ($meta_key)
 401      $meta_key   = wp_unslash( $meta_key );
 402      $meta_value = wp_unslash( $meta_value );
 403  
 404      /**
 405       * Short-circuits deleting metadata of a specific type.
 406       *
 407       * The dynamic portion of the hook name, `$meta_type`, refers to the meta object type
 408       * (post, comment, term, user, or any other type with an associated meta table).
 409       * Returning a non-null value will effectively short-circuit the function.
 410       *
 411       * Possible hook names include:
 412       *
 413       *  - `delete_post_metadata`
 414       *  - `delete_comment_metadata`
 415       *  - `delete_term_metadata`
 416       *  - `delete_user_metadata`
 417       *
 418       * @since 3.1.0
 419       *
 420       * @param null|bool $delete     Whether to allow metadata deletion of the given type.
 421       * @param int       $object_id  ID of the object metadata is for.
 422       * @param string    $meta_key   Metadata key.
 423       * @param mixed     $meta_value Metadata value. Must be serializable if non-scalar.
 424       * @param bool      $delete_all Whether to delete the matching metadata entries
 425       *                              for all objects, ignoring the specified $object_id.
 426       *                              Default false.
 427       */
 428      $check = apply_filters( "delete_{$meta_type}_metadata", null, $object_id, $meta_key, $meta_value, $delete_all );
 429      if ( null !== $check ) {
 430          return (bool) $check;
 431      }
 432  
 433      $_meta_value = $meta_value;
 434      $meta_value  = maybe_serialize( $meta_value );
 435  
 436      $query = $wpdb->prepare( "SELECT $id_column FROM $table WHERE meta_key = %s", $meta_key );
 437  
 438      if ( ! $delete_all ) {
 439          $query .= $wpdb->prepare( " AND $type_column = %d", $object_id );
 440      }
 441  
 442      if ( '' !== $meta_value && null !== $meta_value && false !== $meta_value ) {
 443          $query .= $wpdb->prepare( ' AND meta_value = %s', $meta_value );
 444      }
 445  
 446      $meta_ids = $wpdb->get_col( $query );
 447      if ( ! count( $meta_ids ) ) {
 448          return false;
 449      }
 450  
 451      if ( $delete_all ) {
 452          if ( '' !== $meta_value && null !== $meta_value && false !== $meta_value ) {
 453              $object_ids = $wpdb->get_col( $wpdb->prepare( "SELECT $type_column FROM $table WHERE meta_key = %s AND meta_value = %s", $meta_key, $meta_value ) );
 454          } else {
 455              $object_ids = $wpdb->get_col( $wpdb->prepare( "SELECT $type_column FROM $table WHERE meta_key = %s", $meta_key ) );
 456          }
 457      }
 458  
 459      /**
 460       * Fires immediately before deleting metadata of a specific type.
 461       *
 462       * The dynamic portion of the hook name, `$meta_type`, refers to the meta object type
 463       * (post, comment, term, user, or any other type with an associated meta table).
 464       *
 465       * Possible hook names include:
 466       *
 467       *  - `delete_post_meta`
 468       *  - `delete_comment_meta`
 469       *  - `delete_term_meta`
 470       *  - `delete_user_meta`
 471       *
 472       * @since 3.1.0
 473       *
 474       * @param string[] $meta_ids    An array of metadata entry IDs to delete.
 475       * @param int      $object_id   ID of the object metadata is for.
 476       * @param string   $meta_key    Metadata key.
 477       * @param mixed    $_meta_value Metadata value.
 478       */
 479      do_action( "delete_{$meta_type}_meta", $meta_ids, $object_id, $meta_key, $_meta_value );
 480  
 481      // Old-style action.
 482      if ( 'post' === $meta_type ) {
 483          /**
 484           * Fires immediately before deleting metadata for a post.
 485           *
 486           * @since 2.9.0
 487           *
 488           * @param string[] $meta_ids An array of metadata entry IDs to delete.
 489           */
 490          do_action( 'delete_postmeta', $meta_ids );
 491      }
 492  
 493      $query = "DELETE FROM $table WHERE $id_column IN( " . implode( ',', $meta_ids ) . ' )';
 494  
 495      $count = $wpdb->query( $query );
 496  
 497      if ( ! $count ) {
 498          return false;
 499      }
 500  
 501      if ( $delete_all ) {
 502          $data = (array) $object_ids;
 503      } else {
 504          $data = array( $object_id );
 505      }
 506      wp_cache_delete_multiple( $data, $meta_type . '_meta' );
 507  
 508      /**
 509       * Fires immediately after deleting metadata of a specific type.
 510       *
 511       * The dynamic portion of the hook name, `$meta_type`, refers to the meta object type
 512       * (post, comment, term, user, or any other type with an associated meta table).
 513       *
 514       * Possible hook names include:
 515       *
 516       *  - `deleted_post_meta`
 517       *  - `deleted_comment_meta`
 518       *  - `deleted_term_meta`
 519       *  - `deleted_user_meta`
 520       *
 521       * @since 2.9.0
 522       *
 523       * @param string[] $meta_ids    An array of metadata entry IDs to delete.
 524       * @param int      $object_id   ID of the object metadata is for.
 525       * @param string   $meta_key    Metadata key.
 526       * @param mixed    $_meta_value Metadata value.
 527       */
 528      do_action( "deleted_{$meta_type}_meta", $meta_ids, $object_id, $meta_key, $_meta_value );
 529  
 530      // Old-style action.
 531      if ( 'post' === $meta_type ) {
 532          /**
 533           * Fires immediately after deleting metadata for a post.
 534           *
 535           * @since 2.9.0
 536           *
 537           * @param string[] $meta_ids An array of metadata entry IDs to delete.
 538           */
 539          do_action( 'deleted_postmeta', $meta_ids );
 540      }
 541  
 542      return true;
 543  }
 544  
 545  /**
 546   * Retrieves the value of a metadata field for the specified object type and ID.
 547   *
 548   * If the meta field exists, a single value is returned if `$single` is true,
 549   * or an array of values if it's false.
 550   *
 551   * If the meta field does not exist, the result depends on get_metadata_default().
 552   * By default, an empty string is returned if `$single` is true, or an empty array
 553   * if it's false.
 554   *
 555   * @since 2.9.0
 556   *
 557   * @see get_metadata_raw()
 558   * @see get_metadata_default()
 559   *
 560   * @param string $meta_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
 561   *                          or any other object type with an associated meta table.
 562   * @param int    $object_id ID of the object metadata is for.
 563   * @param string $meta_key  Optional. Metadata key. If not specified, retrieve all metadata for
 564   *                          the specified object. Default empty string.
 565   * @param bool   $single    Optional. If true, return only the first value of the specified `$meta_key`.
 566   *                          This parameter has no effect if `$meta_key` is not specified. Default false.
 567   * @return mixed An array of values if `$single` is false.
 568   *               The value of the meta field if `$single` is true.
 569   *               False for an invalid `$object_id` (non-numeric, zero, or negative value),
 570   *               or if `$meta_type` is not specified.
 571   *               An empty array if a valid but non-existing object ID is passed and `$single` is false.
 572   *               An empty string if a valid but non-existing object ID is passed and `$single` is true.
 573   */
 574  function get_metadata( $meta_type, $object_id, $meta_key = '', $single = false ) {
 575      $value = get_metadata_raw( $meta_type, $object_id, $meta_key, $single );
 576      if ( ! is_null( $value ) ) {
 577          return $value;
 578      }
 579  
 580      return get_metadata_default( $meta_type, $object_id, $meta_key, $single );
 581  }
 582  
 583  /**
 584   * Retrieves raw metadata value for the specified object.
 585   *
 586   * @since 5.5.0
 587   *
 588   * @param string $meta_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
 589   *                          or any other object type with an associated meta table.
 590   * @param int    $object_id ID of the object metadata is for.
 591   * @param string $meta_key  Optional. Metadata key. If not specified, retrieve all metadata for
 592   *                          the specified object. Default empty string.
 593   * @param bool   $single    Optional. If true, return only the first value of the specified `$meta_key`.
 594   *                          This parameter has no effect if `$meta_key` is not specified. Default false.
 595   * @return mixed An array of values if `$single` is false.
 596   *               The value of the meta field if `$single` is true.
 597   *               False for an invalid `$object_id` (non-numeric, zero, or negative value),
 598   *               or if `$meta_type` is not specified.
 599   *               Null if the value does not exist.
 600   */
 601  function get_metadata_raw( $meta_type, $object_id, $meta_key = '', $single = false ) {
 602      if ( ! $meta_type || ! is_numeric( $object_id ) ) {
 603          return false;
 604      }
 605  
 606      $object_id = absint( $object_id );
 607      if ( ! $object_id ) {
 608          return false;
 609      }
 610  
 611      /**
 612       * Short-circuits the return value of a meta field.
 613       *
 614       * The dynamic portion of the hook name, `$meta_type`, refers to the meta object type
 615       * (post, comment, term, user, or any other type with an associated meta table).
 616       * Returning a non-null value will effectively short-circuit the function.
 617       *
 618       * Possible filter names include:
 619       *
 620       *  - `get_post_metadata`
 621       *  - `get_comment_metadata`
 622       *  - `get_term_metadata`
 623       *  - `get_user_metadata`
 624       *
 625       * @since 3.1.0
 626       * @since 5.5.0 Added the `$meta_type` parameter.
 627       *
 628       * @param mixed  $value     The value to return, either a single metadata value or an array
 629       *                          of values depending on the value of `$single`. Default null.
 630       * @param int    $object_id ID of the object metadata is for.
 631       * @param string $meta_key  Metadata key.
 632       * @param bool   $single    Whether to return only the first value of the specified `$meta_key`.
 633       * @param string $meta_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
 634       *                          or any other object type with an associated meta table.
 635       */
 636      $check = apply_filters( "get_{$meta_type}_metadata", null, $object_id, $meta_key, $single, $meta_type );
 637      if ( null !== $check ) {
 638          if ( $single && is_array( $check ) ) {
 639              return $check[0];
 640          } else {
 641              return $check;
 642          }
 643      }
 644  
 645      $meta_cache = wp_cache_get( $object_id, $meta_type . '_meta' );
 646  
 647      if ( ! $meta_cache ) {
 648          $meta_cache = update_meta_cache( $meta_type, array( $object_id ) );
 649          if ( isset( $meta_cache[ $object_id ] ) ) {
 650              $meta_cache = $meta_cache[ $object_id ];
 651          } else {
 652              $meta_cache = null;
 653          }
 654      }
 655  
 656      if ( ! $meta_key ) {
 657          return $meta_cache;
 658      }
 659  
 660      if ( isset( $meta_cache[ $meta_key ] ) ) {
 661          if ( $single ) {
 662              return maybe_unserialize( $meta_cache[ $meta_key ][0] );
 663          } else {
 664              return array_map( 'maybe_unserialize', $meta_cache[ $meta_key ] );
 665          }
 666      }
 667  
 668      return null;
 669  }
 670  
 671  /**
 672   * Retrieves default metadata value for the specified meta key and object.
 673   *
 674   * By default, an empty string is returned if `$single` is true, or an empty array
 675   * if it's false.
 676   *
 677   * @since 5.5.0
 678   *
 679   * @param string $meta_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
 680   *                          or any other object type with an associated meta table.
 681   * @param int    $object_id ID of the object metadata is for.
 682   * @param string $meta_key  Metadata key.
 683   * @param bool   $single    Optional. If true, return only the first value of the specified `$meta_key`.
 684   *                          This parameter has no effect if `$meta_key` is not specified. Default false.
 685   * @return mixed An array of default values if `$single` is false.
 686   *               The default value of the meta field if `$single` is true.
 687   */
 688  function get_metadata_default( $meta_type, $object_id, $meta_key, $single = false ) {
 689      if ( $single ) {
 690          $value = '';
 691      } else {
 692          $value = array();
 693      }
 694  
 695      /**
 696       * Filters the default metadata value for a specified meta key and object.
 697       *
 698       * The dynamic portion of the hook name, `$meta_type`, refers to the meta object type
 699       * (post, comment, term, user, or any other type with an associated meta table).
 700       *
 701       * Possible filter names include:
 702       *
 703       *  - `default_post_metadata`
 704       *  - `default_comment_metadata`
 705       *  - `default_term_metadata`
 706       *  - `default_user_metadata`
 707       *
 708       * @since 5.5.0
 709       *
 710       * @param mixed  $value     The value to return, either a single metadata value or an array
 711       *                          of values depending on the value of `$single`.
 712       * @param int    $object_id ID of the object metadata is for.
 713       * @param string $meta_key  Metadata key.
 714       * @param bool   $single    Whether to return only the first value of the specified `$meta_key`.
 715       * @param string $meta_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
 716       *                          or any other object type with an associated meta table.
 717       */
 718      $value = apply_filters( "default_{$meta_type}_metadata", $value, $object_id, $meta_key, $single, $meta_type );
 719  
 720      if ( ! $single && ! wp_is_numeric_array( $value ) ) {
 721          $value = array( $value );
 722      }
 723  
 724      return $value;
 725  }
 726  
 727  /**
 728   * Determines if a meta field with the given key exists for the given object ID.
 729   *
 730   * @since 3.3.0
 731   *
 732   * @param string $meta_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
 733   *                          or any other object type with an associated meta table.
 734   * @param int    $object_id ID of the object metadata is for.
 735   * @param string $meta_key  Metadata key.
 736   * @return bool Whether a meta field with the given key exists.
 737   */
 738  function metadata_exists( $meta_type, $object_id, $meta_key ) {
 739      if ( ! $meta_type || ! is_numeric( $object_id ) ) {
 740          return false;
 741      }
 742  
 743      $object_id = absint( $object_id );
 744      if ( ! $object_id ) {
 745          return false;
 746      }
 747  
 748      /** This filter is documented in wp-includes/meta.php */
 749      $check = apply_filters( "get_{$meta_type}_metadata", null, $object_id, $meta_key, true, $meta_type );
 750      if ( null !== $check ) {
 751          return (bool) $check;
 752      }
 753  
 754      $meta_cache = wp_cache_get( $object_id, $meta_type . '_meta' );
 755  
 756      if ( ! $meta_cache ) {
 757          $meta_cache = update_meta_cache( $meta_type, array( $object_id ) );
 758          $meta_cache = $meta_cache[ $object_id ];
 759      }
 760  
 761      if ( isset( $meta_cache[ $meta_key ] ) ) {
 762          return true;
 763      }
 764  
 765      return false;
 766  }
 767  
 768  /**
 769   * Retrieves metadata by meta ID.
 770   *
 771   * @since 3.3.0
 772   *
 773   * @global wpdb $wpdb WordPress database abstraction object.
 774   *
 775   * @param string $meta_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
 776   *                          or any other object type with an associated meta table.
 777   * @param int    $meta_id   ID for a specific meta row.
 778   * @return stdClass|false {
 779   *     Metadata object, or boolean `false` if the metadata doesn't exist.
 780   *
 781   *     @type string $meta_key   The meta key.
 782   *     @type mixed  $meta_value The unserialized meta value.
 783   *     @type string $meta_id    Optional. The meta ID when the meta type is any value except 'user'.
 784   *     @type string $umeta_id   Optional. The meta ID when the meta type is 'user'.
 785   *     @type string $post_id    Optional. The object ID when the meta type is 'post'.
 786   *     @type string $comment_id Optional. The object ID when the meta type is 'comment'.
 787   *     @type string $term_id    Optional. The object ID when the meta type is 'term'.
 788   *     @type string $user_id    Optional. The object ID when the meta type is 'user'.
 789   * }
 790   */
 791  function get_metadata_by_mid( $meta_type, $meta_id ) {
 792      global $wpdb;
 793  
 794      if ( ! $meta_type || ! is_numeric( $meta_id ) || floor( $meta_id ) != $meta_id ) {
 795          return false;
 796      }
 797  
 798      $meta_id = (int) $meta_id;
 799      if ( $meta_id <= 0 ) {
 800          return false;
 801      }
 802  
 803      $table = _get_meta_table( $meta_type );
 804      if ( ! $table ) {
 805          return false;
 806      }
 807  
 808      /**
 809       * Short-circuits the return value when fetching a meta field by meta ID.
 810       *
 811       * The dynamic portion of the hook name, `$meta_type`, refers to the meta object type
 812       * (post, comment, term, user, or any other type with an associated meta table).
 813       * Returning a non-null value will effectively short-circuit the function.
 814       *
 815       * Possible hook names include:
 816       *
 817       *  - `get_post_metadata_by_mid`
 818       *  - `get_comment_metadata_by_mid`
 819       *  - `get_term_metadata_by_mid`
 820       *  - `get_user_metadata_by_mid`
 821       *
 822       * @since 5.0.0
 823       *
 824       * @param stdClass|null $value   The value to return.
 825       * @param int           $meta_id Meta ID.
 826       */
 827      $check = apply_filters( "get_{$meta_type}_metadata_by_mid", null, $meta_id );
 828      if ( null !== $check ) {
 829          return $check;
 830      }
 831  
 832      $id_column = ( 'user' === $meta_type ) ? 'umeta_id' : 'meta_id';
 833  
 834      $meta = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM $table WHERE $id_column = %d", $meta_id ) );
 835  
 836      if ( empty( $meta ) ) {
 837          return false;
 838      }
 839  
 840      if ( isset( $meta->meta_value ) ) {
 841          $meta->meta_value = maybe_unserialize( $meta->meta_value );
 842      }
 843  
 844      return $meta;
 845  }
 846  
 847  /**
 848   * Updates metadata by meta ID.
 849   *
 850   * @since 3.3.0
 851   *
 852   * @global wpdb $wpdb WordPress database abstraction object.
 853   *
 854   * @param string       $meta_type  Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
 855   *                                 or any other object type with an associated meta table.
 856   * @param int          $meta_id    ID for a specific meta row.
 857   * @param string       $meta_value Metadata value. Must be serializable if non-scalar.
 858   * @param string|false $meta_key   Optional. You can provide a meta key to update it. Default false.
 859   * @return bool True on successful update, false on failure.
 860   */
 861  function update_metadata_by_mid( $meta_type, $meta_id, $meta_value, $meta_key = false ) {
 862      global $wpdb;
 863  
 864      // Make sure everything is valid.
 865      if ( ! $meta_type || ! is_numeric( $meta_id ) || floor( $meta_id ) != $meta_id ) {
 866          return false;
 867      }
 868  
 869      $meta_id = (int) $meta_id;
 870      if ( $meta_id <= 0 ) {
 871          return false;
 872      }
 873  
 874      $table = _get_meta_table( $meta_type );
 875      if ( ! $table ) {
 876          return false;
 877      }
 878  
 879      $column    = sanitize_key( $meta_type . '_id' );
 880      $id_column = ( 'user' === $meta_type ) ? 'umeta_id' : 'meta_id';
 881  
 882      /**
 883       * Short-circuits updating metadata of a specific type by meta ID.
 884       *
 885       * The dynamic portion of the hook name, `$meta_type`, refers to the meta object type
 886       * (post, comment, term, user, or any other type with an associated meta table).
 887       * Returning a non-null value will effectively short-circuit the function.
 888       *
 889       * Possible hook names include:
 890       *
 891       *  - `update_post_metadata_by_mid`
 892       *  - `update_comment_metadata_by_mid`
 893       *  - `update_term_metadata_by_mid`
 894       *  - `update_user_metadata_by_mid`
 895       *
 896       * @since 5.0.0
 897       *
 898       * @param null|bool    $check      Whether to allow updating metadata for the given type.
 899       * @param int          $meta_id    Meta ID.
 900       * @param mixed        $meta_value Meta value. Must be serializable if non-scalar.
 901       * @param string|false $meta_key   Meta key, if provided.
 902       */
 903      $check = apply_filters( "update_{$meta_type}_metadata_by_mid", null, $meta_id, $meta_value, $meta_key );
 904      if ( null !== $check ) {
 905          return (bool) $check;
 906      }
 907  
 908      // Fetch the meta and go on if it's found.
 909      $meta = get_metadata_by_mid( $meta_type, $meta_id );
 910      if ( $meta ) {
 911          $original_key = $meta->meta_key;
 912          $object_id    = $meta->{$column};
 913  
 914          /*
 915           * If a new meta_key (last parameter) was specified, change the meta key,
 916           * otherwise use the original key in the update statement.
 917           */
 918          if ( false === $meta_key ) {
 919              $meta_key = $original_key;
 920          } elseif ( ! is_string( $meta_key ) ) {
 921              return false;
 922          }
 923  
 924          $meta_subtype = get_object_subtype( $meta_type, $object_id );
 925  
 926          // Sanitize the meta.
 927          $_meta_value = $meta_value;
 928          $meta_value  = sanitize_meta( $meta_key, $meta_value, $meta_type, $meta_subtype );
 929          $meta_value  = maybe_serialize( $meta_value );
 930  
 931          // Format the data query arguments.
 932          $data = array(
 933              'meta_key'   => $meta_key,
 934              'meta_value' => $meta_value,
 935          );
 936  
 937          // Format the where query arguments.
 938          $where               = array();
 939          $where[ $id_column ] = $meta_id;
 940  
 941          /** This action is documented in wp-includes/meta.php */
 942          do_action( "update_{$meta_type}_meta", $meta_id, $object_id, $meta_key, $_meta_value );
 943  
 944          if ( 'post' === $meta_type ) {
 945              /** This action is documented in wp-includes/meta.php */
 946              do_action( 'update_postmeta', $meta_id, $object_id, $meta_key, $meta_value );
 947          }
 948  
 949          // Run the update query, all fields in $data are %s, $where is a %d.
 950          $result = $wpdb->update( $table, $data, $where, '%s', '%d' );
 951          if ( ! $result ) {
 952              return false;
 953          }
 954  
 955          // Clear the caches.
 956          wp_cache_delete( $object_id, $meta_type . '_meta' );
 957  
 958          /** This action is documented in wp-includes/meta.php */
 959          do_action( "updated_{$meta_type}_meta", $meta_id, $object_id, $meta_key, $_meta_value );
 960  
 961          if ( 'post' === $meta_type ) {
 962              /** This action is documented in wp-includes/meta.php */
 963              do_action( 'updated_postmeta', $meta_id, $object_id, $meta_key, $meta_value );
 964          }
 965  
 966          return true;
 967      }
 968  
 969      // And if the meta was not found.
 970      return false;
 971  }
 972  
 973  /**
 974   * Deletes metadata by meta ID.
 975   *
 976   * @since 3.3.0
 977   *
 978   * @global wpdb $wpdb WordPress database abstraction object.
 979   *
 980   * @param string $meta_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
 981   *                          or any other object type with an associated meta table.
 982   * @param int    $meta_id   ID for a specific meta row.
 983   * @return bool True on successful delete, false on failure.
 984   */
 985  function delete_metadata_by_mid( $meta_type, $meta_id ) {
 986      global $wpdb;
 987  
 988      // Make sure everything is valid.
 989      if ( ! $meta_type || ! is_numeric( $meta_id ) || floor( $meta_id ) != $meta_id ) {
 990          return false;
 991      }
 992  
 993      $meta_id = (int) $meta_id;
 994      if ( $meta_id <= 0 ) {
 995          return false;
 996      }
 997  
 998      $table = _get_meta_table( $meta_type );
 999      if ( ! $table ) {
1000          return false;
1001      }
1002  
1003      // Object and ID columns.
1004      $column    = sanitize_key( $meta_type . '_id' );
1005      $id_column = ( 'user' === $meta_type ) ? 'umeta_id' : 'meta_id';
1006  
1007      /**
1008       * Short-circuits deleting metadata of a specific type by meta ID.
1009       *
1010       * The dynamic portion of the hook name, `$meta_type`, refers to the meta object type
1011       * (post, comment, term, user, or any other type with an associated meta table).
1012       * Returning a non-null value will effectively short-circuit the function.
1013       *
1014       * Possible hook names include:
1015       *
1016       *  - `delete_post_metadata_by_mid`
1017       *  - `delete_comment_metadata_by_mid`
1018       *  - `delete_term_metadata_by_mid`
1019       *  - `delete_user_metadata_by_mid`
1020       *
1021       * @since 5.0.0
1022       *
1023       * @param null|bool $delete  Whether to allow metadata deletion of the given type.
1024       * @param int       $meta_id Meta ID.
1025       */
1026      $check = apply_filters( "delete_{$meta_type}_metadata_by_mid", null, $meta_id );
1027      if ( null !== $check ) {
1028          return (bool) $check;
1029      }
1030  
1031      // Fetch the meta and go on if it's found.
1032      $meta = get_metadata_by_mid( $meta_type, $meta_id );
1033      if ( $meta ) {
1034          $object_id = (int) $meta->{$column};
1035  
1036          /** This action is documented in wp-includes/meta.php */
1037          do_action( "delete_{$meta_type}_meta", (array) $meta_id, $object_id, $meta->meta_key, $meta->meta_value );
1038  
1039          // Old-style action.
1040          if ( 'post' === $meta_type || 'comment' === $meta_type ) {
1041              /**
1042               * Fires immediately before deleting post or comment metadata of a specific type.
1043               *
1044               * The dynamic portion of the hook name, `$meta_type`, refers to the meta
1045               * object type (post or comment).
1046               *
1047               * Possible hook names include:
1048               *
1049               *  - `delete_postmeta`
1050               *  - `delete_commentmeta`
1051               *  - `delete_termmeta`
1052               *  - `delete_usermeta`
1053               *
1054               * @since 3.4.0
1055               *
1056               * @param int $meta_id ID of the metadata entry to delete.
1057               */
1058              do_action( "delete_{$meta_type}meta", $meta_id );
1059          }
1060  
1061          // Run the query, will return true if deleted, false otherwise.
1062          $result = (bool) $wpdb->delete( $table, array( $id_column => $meta_id ) );
1063  
1064          // Clear the caches.
1065          wp_cache_delete( $object_id, $meta_type . '_meta' );
1066  
1067          /** This action is documented in wp-includes/meta.php */
1068          do_action( "deleted_{$meta_type}_meta", (array) $meta_id, $object_id, $meta->meta_key, $meta->meta_value );
1069  
1070          // Old-style action.
1071          if ( 'post' === $meta_type || 'comment' === $meta_type ) {
1072              /**
1073               * Fires immediately after deleting post or comment metadata of a specific type.
1074               *
1075               * The dynamic portion of the hook name, `$meta_type`, refers to the meta
1076               * object type (post or comment).
1077               *
1078               * Possible hook names include:
1079               *
1080               *  - `deleted_postmeta`
1081               *  - `deleted_commentmeta`
1082               *  - `deleted_termmeta`
1083               *  - `deleted_usermeta`
1084               *
1085               * @since 3.4.0
1086               *
1087               * @param int $meta_id Deleted metadata entry ID.
1088               */
1089              do_action( "deleted_{$meta_type}meta", $meta_id );
1090          }
1091  
1092          return $result;
1093  
1094      }
1095  
1096      // Meta ID was not found.
1097      return false;
1098  }
1099  
1100  /**
1101   * Updates the metadata cache for the specified objects.
1102   *
1103   * @since 2.9.0
1104   *
1105   * @global wpdb $wpdb WordPress database abstraction object.
1106   *
1107   * @param string       $meta_type  Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
1108   *                                 or any other object type with an associated meta table.
1109   * @param string|int[] $object_ids Array or comma delimited list of object IDs to update cache for.
1110   * @return array|false Metadata cache for the specified objects, or false on failure.
1111   */
1112  function update_meta_cache( $meta_type, $object_ids ) {
1113      global $wpdb;
1114  
1115      if ( ! $meta_type || ! $object_ids ) {
1116          return false;
1117      }
1118  
1119      $table = _get_meta_table( $meta_type );
1120      if ( ! $table ) {
1121          return false;
1122      }
1123  
1124      $column = sanitize_key( $meta_type . '_id' );
1125  
1126      if ( ! is_array( $object_ids ) ) {
1127          $object_ids = preg_replace( '|[^0-9,]|', '', $object_ids );
1128          $object_ids = explode( ',', $object_ids );
1129      }
1130  
1131      $object_ids = array_map( 'intval', $object_ids );
1132  
1133      /**
1134       * Short-circuits updating the metadata cache of a specific type.
1135       *
1136       * The dynamic portion of the hook name, `$meta_type`, refers to the meta object type
1137       * (post, comment, term, user, or any other type with an associated meta table).
1138       * Returning a non-null value will effectively short-circuit the function.
1139       *
1140       * Possible hook names include:
1141       *
1142       *  - `update_post_metadata_cache`
1143       *  - `update_comment_metadata_cache`
1144       *  - `update_term_metadata_cache`
1145       *  - `update_user_metadata_cache`
1146       *
1147       * @since 5.0.0
1148       *
1149       * @param mixed $check      Whether to allow updating the meta cache of the given type.
1150       * @param int[] $object_ids Array of object IDs to update the meta cache for.
1151       */
1152      $check = apply_filters( "update_{$meta_type}_metadata_cache", null, $object_ids );
1153      if ( null !== $check ) {
1154          return (bool) $check;
1155      }
1156  
1157      $cache_key      = $meta_type . '_meta';
1158      $non_cached_ids = array();
1159      $cache          = array();
1160      $cache_values   = wp_cache_get_multiple( $object_ids, $cache_key );
1161  
1162      foreach ( $cache_values as $id => $cached_object ) {
1163          if ( false === $cached_object ) {
1164              $non_cached_ids[] = $id;
1165          } else {
1166              $cache[ $id ] = $cached_object;
1167          }
1168      }
1169  
1170      if ( empty( $non_cached_ids ) ) {
1171          return $cache;
1172      }
1173  
1174      // Get meta info.
1175      $id_list   = implode( ',', $non_cached_ids );
1176      $id_column = ( 'user' === $meta_type ) ? 'umeta_id' : 'meta_id';
1177  
1178      $meta_list = $wpdb->get_results( "SELECT $column, meta_key, meta_value FROM $table WHERE $column IN ($id_list) ORDER BY $id_column ASC", ARRAY_A );
1179  
1180      if ( ! empty( $meta_list ) ) {
1181          foreach ( $meta_list as $metarow ) {
1182              $mpid = (int) $metarow[ $column ];
1183              $mkey = $metarow['meta_key'];
1184              $mval = $metarow['meta_value'];
1185  
1186              // Force subkeys to be array type.
1187              if ( ! isset( $cache[ $mpid ] ) || ! is_array( $cache[ $mpid ] ) ) {
1188                  $cache[ $mpid ] = array();
1189              }
1190              if ( ! isset( $cache[ $mpid ][ $mkey ] ) || ! is_array( $cache[ $mpid ][ $mkey ] ) ) {
1191                  $cache[ $mpid ][ $mkey ] = array();
1192              }
1193  
1194              // Add a value to the current pid/key.
1195              $cache[ $mpid ][ $mkey ][] = $mval;
1196          }
1197      }
1198  
1199      $data = array();
1200      foreach ( $non_cached_ids as $id ) {
1201          if ( ! isset( $cache[ $id ] ) ) {
1202              $cache[ $id ] = array();
1203          }
1204          $data[ $id ] = $cache[ $id ];
1205      }
1206      wp_cache_add_multiple( $data, $cache_key );
1207  
1208      return $cache;
1209  }
1210  
1211  /**
1212   * Retrieves the queue for lazy-loading metadata.
1213   *
1214   * @since 4.5.0
1215   *
1216   * @return WP_Metadata_Lazyloader Metadata lazyloader queue.
1217   */
1218  function wp_metadata_lazyloader() {
1219      static $wp_metadata_lazyloader;
1220  
1221      if ( null === $wp_metadata_lazyloader ) {
1222          $wp_metadata_lazyloader = new WP_Metadata_Lazyloader();
1223      }
1224  
1225      return $wp_metadata_lazyloader;
1226  }
1227  
1228  /**
1229   * Given a meta query, generates SQL clauses to be appended to a main query.
1230   *
1231   * @since 3.2.0
1232   *
1233   * @see WP_Meta_Query
1234   *
1235   * @param array  $meta_query        A meta query.
1236   * @param string $type              Type of meta.
1237   * @param string $primary_table     Primary database table name.
1238   * @param string $primary_id_column Primary ID column name.
1239   * @param object $context           Optional. The main query object. Default null.
1240   * @return string[]|false {
1241   *     Array containing JOIN and WHERE SQL clauses to append to the main query,
1242   *     or false if no table exists for the requested meta type.
1243   *
1244   *     @type string $join  SQL fragment to append to the main JOIN clause.
1245   *     @type string $where SQL fragment to append to the main WHERE clause.
1246   * }
1247   */
1248  function get_meta_sql( $meta_query, $type, $primary_table, $primary_id_column, $context = null ) {
1249      $meta_query_obj = new WP_Meta_Query( $meta_query );
1250      return $meta_query_obj->get_sql( $type, $primary_table, $primary_id_column, $context );
1251  }
1252  
1253  /**
1254   * Retrieves the name of the metadata table for the specified object type.
1255   *
1256   * @since 2.9.0
1257   *
1258   * @global wpdb $wpdb WordPress database abstraction object.
1259   *
1260   * @param string $type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
1261   *                     or any other object type with an associated meta table.
1262   * @return string|false Metadata table name, or false if no metadata table exists
1263   */
1264  function _get_meta_table( $type ) {
1265      global $wpdb;
1266  
1267      $table_name = $type . 'meta';
1268  
1269      if ( empty( $wpdb->$table_name ) ) {
1270          return false;
1271      }
1272  
1273      return $wpdb->$table_name;
1274  }
1275  
1276  /**
1277   * Determines whether a meta key is considered protected.
1278   *
1279   * @since 3.1.3
1280   *
1281   * @param string $meta_key  Metadata key.
1282   * @param string $meta_type Optional. Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
1283   *                          or any other object type with an associated meta table. Default empty string.
1284   * @return bool Whether the meta key is considered protected.
1285   */
1286  function is_protected_meta( $meta_key, $meta_type = '' ) {
1287      $sanitized_key = preg_replace( "/[^\x20-\x7E\p{L}]/", '', $meta_key );
1288      $protected     = strlen( $sanitized_key ) > 0 && ( '_' === $sanitized_key[0] );
1289  
1290      /**
1291       * Filters whether a meta key is considered protected.
1292       *
1293       * @since 3.2.0
1294       *
1295       * @param bool   $protected Whether the key is considered protected.
1296       * @param string $meta_key  Metadata key.
1297       * @param string $meta_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
1298       *                          or any other object type with an associated meta table.
1299       */
1300      return apply_filters( 'is_protected_meta', $protected, $meta_key, $meta_type );
1301  }
1302  
1303  /**
1304   * Sanitizes meta value.
1305   *
1306   * @since 3.1.3
1307   * @since 4.9.8 The `$object_subtype` parameter was added.
1308   *
1309   * @param string $meta_key       Metadata key.
1310   * @param mixed  $meta_value     Metadata value to sanitize.
1311   * @param string $object_type    Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
1312   *                               or any other object type with an associated meta table.
1313   * @param string $object_subtype Optional. The subtype of the object type. Default empty string.
1314   * @return mixed Sanitized $meta_value.
1315   */
1316  function sanitize_meta( $meta_key, $meta_value, $object_type, $object_subtype = '' ) {
1317      if ( ! empty( $object_subtype ) && has_filter( "sanitize_{$object_type}_meta_{$meta_key}_for_{$object_subtype}" ) ) {
1318  
1319          /**
1320           * Filters the sanitization of a specific meta key of a specific meta type and subtype.
1321           *
1322           * The dynamic portions of the hook name, `$object_type`, `$meta_key`,
1323           * and `$object_subtype`, refer to the metadata object type (comment, post, term, or user),
1324           * the meta key value, and the object subtype respectively.
1325           *
1326           * @since 4.9.8
1327           *
1328           * @param mixed  $meta_value     Metadata value to sanitize.
1329           * @param string $meta_key       Metadata key.
1330           * @param string $object_type    Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
1331           *                               or any other object type with an associated meta table.
1332           * @param string $object_subtype Object subtype.
1333           */
1334          return apply_filters( "sanitize_{$object_type}_meta_{$meta_key}_for_{$object_subtype}", $meta_value, $meta_key, $object_type, $object_subtype );
1335      }
1336  
1337      /**
1338       * Filters the sanitization of a specific meta key of a specific meta type.
1339       *
1340       * The dynamic portions of the hook name, `$meta_type`, and `$meta_key`,
1341       * refer to the metadata object type (comment, post, term, or user) and the meta
1342       * key value, respectively.
1343       *
1344       * @since 3.3.0
1345       *
1346       * @param mixed  $meta_value  Metadata value to sanitize.
1347       * @param string $meta_key    Metadata key.
1348       * @param string $object_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
1349       *                            or any other object type with an associated meta table.
1350       */
1351      return apply_filters( "sanitize_{$object_type}_meta_{$meta_key}", $meta_value, $meta_key, $object_type );
1352  }
1353  
1354  /**
1355   * Registers a meta key.
1356   *
1357   * It is recommended to register meta keys for a specific combination of object type and object subtype. If passing
1358   * an object subtype is omitted, the meta key will be registered for the entire object type, however it can be partly
1359   * overridden in case a more specific meta key of the same name exists for the same object type and a subtype.
1360   *
1361   * If an object type does not support any subtypes, such as users or comments, you should commonly call this function
1362   * without passing a subtype.
1363   *
1364   * @since 3.3.0
1365   * @since 4.6.0 {@link https://core.trac.wordpress.org/ticket/35658 Modified
1366   *              to support an array of data to attach to registered meta keys}. Previous arguments for
1367   *              `$sanitize_callback` and `$auth_callback` have been folded into this array.
1368   * @since 4.9.8 The `$object_subtype` argument was added to the arguments array.
1369   * @since 5.3.0 Valid meta types expanded to include "array" and "object".
1370   * @since 5.5.0 The `$default` argument was added to the arguments array.
1371   * @since 6.4.0 The `$revisions_enabled` argument was added to the arguments array.
1372   * @since 6.7.0 The `label` argument was added to the arguments array.
1373   *
1374   * @param string       $object_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
1375   *                                  or any other object type with an associated meta table.
1376   * @param string       $meta_key    Meta key to register.
1377   * @param array        $args {
1378   *     Data used to describe the meta key when registered.
1379   *
1380   *     @type string     $object_subtype    A subtype; e.g. if the object type is "post", the post type. If left empty,
1381   *                                         the meta key will be registered on the entire object type. Default empty.
1382   *     @type string     $type              The type of data associated with this meta key.
1383   *                                         Valid values are 'string', 'boolean', 'integer', 'number', 'array', and 'object'.
1384   *     @type string     $label             A human-readable label of the data attached to this meta key.
1385   *     @type string     $description       A description of the data attached to this meta key.
1386   *     @type bool       $single            Whether the meta key has one value per object, or an array of values per object.
1387   *     @type mixed      $default           The default value returned from get_metadata() if no value has been set yet.
1388   *                                         When using a non-single meta key, the default value is for the first entry.
1389   *                                         In other words, when calling get_metadata() with `$single` set to `false`,
1390   *                                         the default value given here will be wrapped in an array.
1391   *     @type callable   $sanitize_callback A function or method to call when sanitizing `$meta_key` data.
1392   *     @type callable   $auth_callback     Optional. A function or method to call when performing edit_post_meta,
1393   *                                         add_post_meta, and delete_post_meta capability checks.
1394   *     @type bool|array $show_in_rest      Whether data associated with this meta key can be considered public and
1395   *                                         should be accessible via the REST API. A custom post type must also declare
1396   *                                         support for custom fields for registered meta to be accessible via REST.
1397   *                                         When registering complex meta values this argument may optionally be an
1398   *                                         array with 'schema' or 'prepare_callback' keys instead of a boolean.
1399   *     @type bool       $revisions_enabled Whether to enable revisions support for this meta_key. Can only be used when the
1400   *                                         object type is 'post'.
1401   * }
1402   * @param string|array $deprecated Deprecated. Use `$args` instead.
1403   * @return bool True if the meta key was successfully registered in the global array, false if not.
1404   *              Registering a meta key with distinct sanitize and auth callbacks will fire those callbacks,
1405   *              but will not add to the global registry.
1406   */
1407  function register_meta( $object_type, $meta_key, $args, $deprecated = null ) {
1408      global $wp_meta_keys;
1409  
1410      if ( ! is_array( $wp_meta_keys ) ) {
1411          $wp_meta_keys = array();
1412      }
1413  
1414      $defaults = array(
1415          'object_subtype'    => '',
1416          'type'              => 'string',
1417          'label'             => '',
1418          'description'       => '',
1419          'default'           => '',
1420          'single'            => false,
1421          'sanitize_callback' => null,
1422          'auth_callback'     => null,
1423          'show_in_rest'      => false,
1424          'revisions_enabled' => false,
1425      );
1426  
1427      // There used to be individual args for sanitize and auth callbacks.
1428      $has_old_sanitize_cb = false;
1429      $has_old_auth_cb     = false;
1430  
1431      if ( is_callable( $args ) ) {
1432          $args = array(
1433              'sanitize_callback' => $args,
1434          );
1435  
1436          $has_old_sanitize_cb = true;
1437      } else {
1438          $args = (array) $args;
1439      }
1440  
1441      if ( is_callable( $deprecated ) ) {
1442          $args['auth_callback'] = $deprecated;
1443          $has_old_auth_cb       = true;
1444      }
1445  
1446      /**
1447       * Filters the registration arguments when registering meta.
1448       *
1449       * @since 4.6.0
1450       *
1451       * @param array  $args        Array of meta registration arguments.
1452       * @param array  $defaults    Array of default arguments.
1453       * @param string $object_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
1454       *                            or any other object type with an associated meta table.
1455       * @param string $meta_key    Meta key.
1456       */
1457      $args = apply_filters( 'register_meta_args', $args, $defaults, $object_type, $meta_key );
1458      unset( $defaults['default'] );
1459      $args = wp_parse_args( $args, $defaults );
1460  
1461      // Require an item schema when registering array meta.
1462      if ( false !== $args['show_in_rest'] && 'array' === $args['type'] ) {
1463          if ( ! is_array( $args['show_in_rest'] ) || ! isset( $args['show_in_rest']['schema']['items'] ) ) {
1464              _doing_it_wrong( __FUNCTION__, __( 'When registering an "array" meta type to show in the REST API, you must specify the schema for each array item in "show_in_rest.schema.items".' ), '5.3.0' );
1465  
1466              return false;
1467          }
1468      }
1469  
1470      $object_subtype = ! empty( $args['object_subtype'] ) ? $args['object_subtype'] : '';
1471      if ( $args['revisions_enabled'] ) {
1472          if ( 'post' !== $object_type ) {
1473              _doing_it_wrong( __FUNCTION__, __( 'Meta keys cannot enable revisions support unless the object type supports revisions.' ), '6.4.0' );
1474  
1475              return false;
1476          } elseif ( ! empty( $object_subtype ) && ! post_type_supports( $object_subtype, 'revisions' ) ) {
1477              _doing_it_wrong( __FUNCTION__, __( 'Meta keys cannot enable revisions support unless the object subtype supports revisions.' ), '6.4.0' );
1478  
1479              return false;
1480          }
1481      }
1482  
1483      // If `auth_callback` is not provided, fall back to `is_protected_meta()`.
1484      if ( empty( $args['auth_callback'] ) ) {
1485          if ( is_protected_meta( $meta_key, $object_type ) ) {
1486              $args['auth_callback'] = '__return_false';
1487          } else {
1488              $args['auth_callback'] = '__return_true';
1489          }
1490      }
1491  
1492      // Back-compat: old sanitize and auth callbacks are applied to all of an object type.
1493      if ( is_callable( $args['sanitize_callback'] ) ) {
1494          if ( ! empty( $object_subtype ) ) {
1495              add_filter( "sanitize_{$object_type}_meta_{$meta_key}_for_{$object_subtype}", $args['sanitize_callback'], 10, 4 );
1496          } else {
1497              add_filter( "sanitize_{$object_type}_meta_{$meta_key}", $args['sanitize_callback'], 10, 3 );
1498          }
1499      }
1500  
1501      if ( is_callable( $args['auth_callback'] ) ) {
1502          if ( ! empty( $object_subtype ) ) {
1503              add_filter( "auth_{$object_type}_meta_{$meta_key}_for_{$object_subtype}", $args['auth_callback'], 10, 6 );
1504          } else {
1505              add_filter( "auth_{$object_type}_meta_{$meta_key}", $args['auth_callback'], 10, 6 );
1506          }
1507      }
1508  
1509      if ( array_key_exists( 'default', $args ) ) {
1510          $schema = $args;
1511          if ( is_array( $args['show_in_rest'] ) && isset( $args['show_in_rest']['schema'] ) ) {
1512              $schema = array_merge( $schema, $args['show_in_rest']['schema'] );
1513          }
1514  
1515          $check = rest_validate_value_from_schema( $args['default'], $schema );
1516          if ( is_wp_error( $check ) ) {
1517              _doing_it_wrong( __FUNCTION__, __( 'When registering a default meta value the data must match the type provided.' ), '5.5.0' );
1518  
1519              return false;
1520          }
1521  
1522          if ( ! has_filter( "default_{$object_type}_metadata", 'filter_default_metadata' ) ) {
1523              add_filter( "default_{$object_type}_metadata", 'filter_default_metadata', 10, 5 );
1524          }
1525      }
1526  
1527      // Global registry only contains meta keys registered with the array of arguments added in 4.6.0.
1528      if ( ! $has_old_auth_cb && ! $has_old_sanitize_cb ) {
1529          unset( $args['object_subtype'] );
1530  
1531          $wp_meta_keys[ $object_type ][ $object_subtype ][ $meta_key ] = $args;
1532  
1533          return true;
1534      }
1535  
1536      return false;
1537  }
1538  
1539  /**
1540   * Filters into default_{$object_type}_metadata and adds in default value.
1541   *
1542   * @since 5.5.0
1543   *
1544   * @param mixed  $value     Current value passed to filter.
1545   * @param int    $object_id ID of the object metadata is for.
1546   * @param string $meta_key  Metadata key.
1547   * @param bool   $single    If true, return only the first value of the specified `$meta_key`.
1548   *                          This parameter has no effect if `$meta_key` is not specified.
1549   * @param string $meta_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
1550   *                          or any other object type with an associated meta table.
1551   * @return mixed An array of default values if `$single` is false.
1552   *               The default value of the meta field if `$single` is true.
1553   */
1554  function filter_default_metadata( $value, $object_id, $meta_key, $single, $meta_type ) {
1555      global $wp_meta_keys;
1556  
1557      if ( wp_installing() ) {
1558          return $value;
1559      }
1560  
1561      if ( ! is_array( $wp_meta_keys ) || ! isset( $wp_meta_keys[ $meta_type ] ) ) {
1562          return $value;
1563      }
1564  
1565      $defaults = array();
1566      foreach ( $wp_meta_keys[ $meta_type ] as $sub_type => $meta_data ) {
1567          foreach ( $meta_data as $_meta_key => $args ) {
1568              if ( $_meta_key === $meta_key && array_key_exists( 'default', $args ) ) {
1569                  $defaults[ $sub_type ] = $args;
1570              }
1571          }
1572      }
1573  
1574      if ( ! $defaults ) {
1575          return $value;
1576      }
1577  
1578      // If this meta type does not have subtypes, then the default is keyed as an empty string.
1579      if ( isset( $defaults[''] ) ) {
1580          $metadata = $defaults[''];
1581      } else {
1582          $sub_type = get_object_subtype( $meta_type, $object_id );
1583          if ( ! isset( $defaults[ $sub_type ] ) ) {
1584              return $value;
1585          }
1586          $metadata = $defaults[ $sub_type ];
1587      }
1588  
1589      if ( $single ) {
1590          $value = $metadata['default'];
1591      } else {
1592          $value = array( $metadata['default'] );
1593      }
1594  
1595      return $value;
1596  }
1597  
1598  /**
1599   * Checks if a meta key is registered.
1600   *
1601   * @since 4.6.0
1602   * @since 4.9.8 The `$object_subtype` parameter was added.
1603   *
1604   * @param string $object_type    Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
1605   *                               or any other object type with an associated meta table.
1606   * @param string $meta_key       Metadata key.
1607   * @param string $object_subtype Optional. The subtype of the object type. Default empty string.
1608   * @return bool True if the meta key is registered to the object type and, if provided,
1609   *              the object subtype. False if not.
1610   */
1611  function registered_meta_key_exists( $object_type, $meta_key, $object_subtype = '' ) {
1612      $meta_keys = get_registered_meta_keys( $object_type, $object_subtype );
1613  
1614      return isset( $meta_keys[ $meta_key ] );
1615  }
1616  
1617  /**
1618   * Unregisters a meta key from the list of registered keys.
1619   *
1620   * @since 4.6.0
1621   * @since 4.9.8 The `$object_subtype` parameter was added.
1622   *
1623   * @param string $object_type    Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
1624   *                               or any other object type with an associated meta table.
1625   * @param string $meta_key       Metadata key.
1626   * @param string $object_subtype Optional. The subtype of the object type. Default empty string.
1627   * @return bool True if successful. False if the meta key was not registered.
1628   */
1629  function unregister_meta_key( $object_type, $meta_key, $object_subtype = '' ) {
1630      global $wp_meta_keys;
1631  
1632      if ( ! registered_meta_key_exists( $object_type, $meta_key, $object_subtype ) ) {
1633          return false;
1634      }
1635  
1636      $args = $wp_meta_keys[ $object_type ][ $object_subtype ][ $meta_key ];
1637  
1638      if ( isset( $args['sanitize_callback'] ) && is_callable( $args['sanitize_callback'] ) ) {
1639          if ( ! empty( $object_subtype ) ) {
1640              remove_filter( "sanitize_{$object_type}_meta_{$meta_key}_for_{$object_subtype}", $args['sanitize_callback'] );
1641          } else {
1642              remove_filter( "sanitize_{$object_type}_meta_{$meta_key}", $args['sanitize_callback'] );
1643          }
1644      }
1645  
1646      if ( isset( $args['auth_callback'] ) && is_callable( $args['auth_callback'] ) ) {
1647          if ( ! empty( $object_subtype ) ) {
1648              remove_filter( "auth_{$object_type}_meta_{$meta_key}_for_{$object_subtype}", $args['auth_callback'] );
1649          } else {
1650              remove_filter( "auth_{$object_type}_meta_{$meta_key}", $args['auth_callback'] );
1651          }
1652      }
1653  
1654      unset( $wp_meta_keys[ $object_type ][ $object_subtype ][ $meta_key ] );
1655  
1656      // Do some clean up.
1657      if ( empty( $wp_meta_keys[ $object_type ][ $object_subtype ] ) ) {
1658          unset( $wp_meta_keys[ $object_type ][ $object_subtype ] );
1659      }
1660      if ( empty( $wp_meta_keys[ $object_type ] ) ) {
1661          unset( $wp_meta_keys[ $object_type ] );
1662      }
1663  
1664      return true;
1665  }
1666  
1667  /**
1668   * Retrieves a list of registered metadata args for an object type, keyed by their meta keys.
1669   *
1670   * @since 4.6.0
1671   * @since 4.9.8 The `$object_subtype` parameter was added.
1672   *
1673   * @param string $object_type    Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
1674   *                               or any other object type with an associated meta table.
1675   * @param string $object_subtype Optional. The subtype of the object type. Default empty string.
1676   * @return array[] List of registered metadata args, keyed by their meta keys.
1677   */
1678  function get_registered_meta_keys( $object_type, $object_subtype = '' ) {
1679      global $wp_meta_keys;
1680  
1681      if ( ! is_array( $wp_meta_keys ) || ! isset( $wp_meta_keys[ $object_type ] ) || ! isset( $wp_meta_keys[ $object_type ][ $object_subtype ] ) ) {
1682          return array();
1683      }
1684  
1685      return $wp_meta_keys[ $object_type ][ $object_subtype ];
1686  }
1687  
1688  /**
1689   * Retrieves registered metadata for a specified object.
1690   *
1691   * The results include both meta that is registered specifically for the
1692   * object's subtype and meta that is registered for the entire object type.
1693   *
1694   * @since 4.6.0
1695   *
1696   * @param string $object_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
1697   *                            or any other object type with an associated meta table.
1698   * @param int    $object_id   ID of the object the metadata is for.
1699   * @param string $meta_key    Optional. Registered metadata key. If not specified, retrieve all registered
1700   *                            metadata for the specified object.
1701   * @return mixed A single value or array of values for a key if specified. An array of all registered keys
1702   *               and values for an object ID if not. False if a given $meta_key is not registered.
1703   */
1704  function get_registered_metadata( $object_type, $object_id, $meta_key = '' ) {
1705      $object_subtype = get_object_subtype( $object_type, $object_id );
1706  
1707      if ( ! empty( $meta_key ) ) {
1708          if ( ! empty( $object_subtype ) && ! registered_meta_key_exists( $object_type, $meta_key, $object_subtype ) ) {
1709              $object_subtype = '';
1710          }
1711  
1712          if ( ! registered_meta_key_exists( $object_type, $meta_key, $object_subtype ) ) {
1713              return false;
1714          }
1715  
1716          $meta_keys     = get_registered_meta_keys( $object_type, $object_subtype );
1717          $meta_key_data = $meta_keys[ $meta_key ];
1718  
1719          $data = get_metadata( $object_type, $object_id, $meta_key, $meta_key_data['single'] );
1720  
1721          return $data;
1722      }
1723  
1724      $data = get_metadata( $object_type, $object_id );
1725      if ( ! $data ) {
1726          return array();
1727      }
1728  
1729      $meta_keys = get_registered_meta_keys( $object_type );
1730      if ( ! empty( $object_subtype ) ) {
1731          $meta_keys = array_merge( $meta_keys, get_registered_meta_keys( $object_type, $object_subtype ) );
1732      }
1733  
1734      return array_intersect_key( $data, $meta_keys );
1735  }
1736  
1737  /**
1738   * Filters out `register_meta()` args based on an allowed list.
1739   *
1740   * `register_meta()` args may change over time, so requiring the allowed list
1741   * to be explicitly turned off is a warranty seal of sorts.
1742   *
1743   * @access private
1744   * @since 5.5.0
1745   *
1746   * @param array $args         Arguments from `register_meta()`.
1747   * @param array $default_args Default arguments for `register_meta()`.
1748   * @return array Filtered arguments.
1749   */
1750  function _wp_register_meta_args_allowed_list( $args, $default_args ) {
1751      return array_intersect_key( $args, $default_args );
1752  }
1753  
1754  /**
1755   * Returns the object subtype for a given object ID of a specific type.
1756   *
1757   * @since 4.9.8
1758   *
1759   * @param string $object_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
1760   *                            or any other object type with an associated meta table.
1761   * @param int    $object_id   ID of the object to retrieve its subtype.
1762   * @return string The object subtype or an empty string if unspecified subtype.
1763   */
1764  function get_object_subtype( $object_type, $object_id ) {
1765      $object_id      = (int) $object_id;
1766      $object_subtype = '';
1767  
1768      switch ( $object_type ) {
1769          case 'post':
1770              $post_type = get_post_type( $object_id );
1771  
1772              if ( ! empty( $post_type ) ) {
1773                  $object_subtype = $post_type;
1774              }
1775              break;
1776  
1777          case 'term':
1778              $term = get_term( $object_id );
1779              if ( ! $term instanceof WP_Term ) {
1780                  break;
1781              }
1782  
1783              $object_subtype = $term->taxonomy;
1784              break;
1785  
1786          case 'comment':
1787              $comment = get_comment( $object_id );
1788              if ( ! $comment ) {
1789                  break;
1790              }
1791  
1792              $object_subtype = 'comment';
1793              break;
1794  
1795          case 'user':
1796              $user = get_user_by( 'id', $object_id );
1797              if ( ! $user ) {
1798                  break;
1799              }
1800  
1801              $object_subtype = 'user';
1802              break;
1803      }
1804  
1805      /**
1806       * Filters the object subtype identifier for a non-standard object type.
1807       *
1808       * The dynamic portion of the hook name, `$object_type`, refers to the meta object type
1809       * (post, comment, term, user, or any other type with an associated meta table).
1810       *
1811       * Possible hook names include:
1812       *
1813       *  - `get_object_subtype_post`
1814       *  - `get_object_subtype_comment`
1815       *  - `get_object_subtype_term`
1816       *  - `get_object_subtype_user`
1817       *
1818       * @since 4.9.8
1819       *
1820       * @param string $object_subtype Empty string to override.
1821       * @param int    $object_id      ID of the object to get the subtype for.
1822       */
1823      return apply_filters( "get_object_subtype_{$object_type}", $object_subtype, $object_id );
1824  }


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