The metadata_exists() WordPress PHP function checks if a meta field with the given key exists for the specified object ID.
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Usage
To use the function, provide the type of object metadata is for, the object ID, and the metadata key.
metadata_exists( $meta_type, $object_id, $meta_key );
Parameters
$meta_type(string) – Required. Type of object metadata is for. Accepts ‘post’, ‘comment’, ‘term’, ‘user’, or any other object type with an associated meta table.$object_id(int) – Required. ID of the object metadata is for.$meta_key(string) – Required. Metadata key.
More information
See WordPress Developer Resources: metadata_exists
Examples
Check if term metadata exists and retrieve it
if (metadata_exists('term', $term_id, '_meta_key')) {
$meta_value = get_term_meta($term_id, '_meta_key', true);
}
Check if post metadata exists and retrieve it
if (metadata_exists('post', $post_id, '_meta_key')) {
$meta_value = get_post_meta($post_id, '_meta_key', true);
}
Check if user metadata exists and retrieve it
if (metadata_exists('user', $user_id, '_meta_key')) {
$meta_value = get_user_meta($user_id, '_meta_key', true);
}
Check if comment metadata exists and retrieve it
if (metadata_exists('comment', $comment_id, '_meta_key')) {
$meta_value = get_comment_meta($comment_id, '_meta_key', true);
}
Check if custom object type metadata exists and retrieve it
if (metadata_exists('custom_object', $custom_object_id, '_meta_key')) {
$meta_value = get_metadata('custom_object', $custom_object_id, '_meta_key', true);
}