get_metadata( string $meta_type, int $object_id, string $meta_key = '', bool $single = false )

Retrieve metadata for the specified object.

Contents

Description Description

Parameters Parameters

$meta_type

(string) (Required) Type of object metadata is for (e.g., comment, post, term, or user).

$object_id

(int) (Required) ID of the object metadata is for

$meta_key

(string) (Optional) Metadata key. If not specified, retrieve all metadata for the specified object.

Default value: ''

$single

(bool) (Optional) If true, return only the first value of the specified meta_key. This parameter has no effect if meta_key is not specified.

Default value: false

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Return Return

(mixed) Single metadata value, or array of values

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Source Source

File: wp-includes/meta.php

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function get_metadata( $meta_type, $object_id, $meta_key = '', $single = false ) {
    if ( ! $meta_type || ! is_numeric( $object_id ) ) {
        return false;
    }
 
    $object_id = absint( $object_id );
    if ( ! $object_id ) {
        return false;
    }
 
    /**
     * Filters whether to retrieve metadata of a specific type.
     *
     * The dynamic portion of the hook, `$meta_type`, refers to the meta
     * object type (comment, post, term, or user). Returning a non-null value
     * will effectively short-circuit the function.
     *
     * @since 3.1.0
     *
     * @param null|array|string $value     The value get_metadata() should return - a single metadata value,
     *                                     or an array of values.
     * @param int               $object_id Object ID.
     * @param string            $meta_key  Meta key.
     * @param bool              $single    Whether to return only the first value of the specified $meta_key.
     */
    $check = apply_filters( "get_{$meta_type}_metadata", null, $object_id, $meta_key, $single );
    if ( null !== $check ) {
        if ( $single && is_array( $check ) ) {
            return $check[0];
        } else {
            return $check;
        }
    }
 
    $meta_cache = wp_cache_get( $object_id, $meta_type . '_meta' );
 
    if ( ! $meta_cache ) {
        $meta_cache = update_meta_cache( $meta_type, array( $object_id ) );
        $meta_cache = $meta_cache[ $object_id ];
    }
 
    if ( ! $meta_key ) {
        return $meta_cache;
    }
 
    if ( isset( $meta_cache[ $meta_key ] ) ) {
        if ( $single ) {
            return maybe_unserialize( $meta_cache[ $meta_key ][0] );
        } else {
            return array_map( 'maybe_unserialize', $meta_cache[ $meta_key ] );
        }
    }
 
    if ( $single ) {
        return '';
    } else {
        return array();
    }
}

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Changelog Changelog

Changelog
Version Description
2.9.0 Introduced.

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Uses Uses

Uses
Uses Description
wp-includes/cache.php: wp_cache_get()

Retrieves the cache contents from the cache by key and group.
wp-includes/functions.php: absint()

Convert a value to non-negative integer.
wp-includes/functions.php: maybe_unserialize()

Unserialize value only if it was serialized.
wp-includes/plugin.php: apply_filters()

Call the functions added to a filter hook.
wp-includes/meta.php: update_meta_cache()

Update the metadata cache for the specified objects.
wp-includes/meta.php: get_{$meta_type}_metadata

Filters whether to retrieve metadata of a specific type.
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Used By Used By

Used By
Used By Description
wp-includes/ms-site.php: get_site_meta()

Retrieves metadata for a site.
wp-includes/rest-api/fields/class-wp-rest-meta-fields.php: WP_REST_Meta_Fields::update_multi_meta_value()

Updates multiple meta values for an object.
wp-includes/rest-api/fields/class-wp-rest-meta-fields.php: WP_REST_Meta_Fields::update_meta_value()

Updates a meta value for an object.
wp-includes/rest-api/fields/class-wp-rest-meta-fields.php: WP_REST_Meta_Fields::get_value()

Retrieves the meta field value.
wp-includes/meta.php: get_registered_metadata()

Retrieves registered metadata for a specified object.
wp-includes/taxonomy.php: get_term_meta()

Retrieves metadata for a term.
wp-includes/user.php: get_user_meta()

Retrieve user meta field for a user.
wp-includes/post.php: get_post_meta()

Retrieves a post meta field for the given post ID.
wp-includes/comment.php: get_comment_meta()

Retrieve comment meta field for a comment.
wp-includes/meta.php: update_metadata()

Update metadata for the specified object. If no value already exists for the specified object ID and metadata key, the metadata will be added.
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