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metadata_exists()

metadata_exists( string $meta_type, int $object_id, string $meta_key ): bool

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Determines if a meta field with the given key exists for the given object ID.

Parameters

$meta_typestringrequired
Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user', or any other object type with an associated meta table.
$object_idintrequired
ID of the object metadata is for.
$meta_keystringrequired
Metadata key.

Return

bool Whether a meta field with the given key exists.

Source

function metadata_exists( $meta_type, $object_id, $meta_key ) {
	if ( ! $meta_type || ! is_numeric( $object_id ) ) {
		return false;
	}

	$object_id = absint( $object_id );
	if ( ! $object_id ) {
		return false;
	}

	/** This filter is documented in wp-includes/meta.php */
	$check = apply_filters( "get_{$meta_type}_metadata", null, $object_id, $meta_key, true, $meta_type );
	if ( null !== $check ) {
		return (bool) $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 ( isset( $meta_cache[ $meta_key ] ) ) {
		return true;
	}

	return false;
}

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Hooks

apply_filters( “get_{$meta_type}_metadata”, mixed $value, int $object_id, string $meta_key, bool $single, string $meta_type )

Short-circuits the return value of a meta field.

UsesDescription
update_meta_cache()wp-includes/meta.php

Updates the metadata cache for the specified objects.

wp_cache_get()wp-includes/cache.php

Retrieves the cache contents from the cache by key and group.

absint()wp-includes/functions.php

Converts a value to non-negative integer.

apply_filters()wp-includes/plugin.php

Calls the callback functions that have been added to a filter hook.

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Used byDescription
wp_save_revisioned_meta_fields()wp-includes/revision.php

Save the revisioned meta fields.

wp_install_defaults()wp-admin/includes/upgrade.php

Creates the initial content for a newly-installed site.

WP_User::__isset()wp-includes/class-wp-user.php

Magic method for checking the existence of a certain custom field.

WP_Post::__isset()wp-includes/class-wp-post.php

Isset-er.

Changelog

VersionDescription
3.3.0Introduced.

User Contributed Notes

  1. Skip to note 3 content
    vutuansw
    You must log in to vote on the helpfulness of this noteVote results for this note: 1You must log in to vote on the helpfulness of this note
    // Check and get a term meta

if ( metadata_exists( 'term', $term_id, '_meta_key' ) ) {
	$meta_value = get_term_meta( $term_id, '_meta_key', true );
}

// Check and get a post meta

if ( metadata_exists( 'post', $post_id, '_meta_key' ) ) {
	$meta_value = get_post_meta( $post_id, '_meta_key', true );
}

// Check and get a user meta

if ( metadata_exists( 'user', $user_id, '_meta_key' ) ) {
	$meta_value = get_user_meta( $user_id, '_meta_key', true );
}

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