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

User Contributed Notes

1. Skip to note 3 content

   leogermani 7 years ago

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   Note that although this filter filters the value that will be returned, you do not receive the current value as the first parameter.

   You allways receive null in the first parameter.

   If your callback returns anything else than null, this is the value that the function will return at the end. If you return null, the function will continue to run normally and try to fetch the data from the database (or cache).

   • Actually – you do not “always receive NULL” as the first parameter.While it is true that WordPress calls the first (as possibly ONLY) filter in the sequence with a NULL $value, you should allow for the possibility that a higher-priority filter could be passing down a $value to your filter!To play nice with other plug-ins, rather than your filter returning a hard-coded “null” if it decides to take no action, it may be appropriate for your filter to return the $value (which may be null, or may be the value injected by an earlier filter!)

     Andy Schmidt 7 years ago
2. Skip to note 4 content

   Steven Lin 4 years ago

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   Example migrated from Codex:

   add_action( 'init', 'wpdocs_init' );
   
   function wpdocs_init() {
   	add_filter( 'get_user_metadata', 'wpdocs_get_foo', 10, 3 );
   }
   
   function wpdocs_get_foo( $check, $object_id, $meta_key ) {
   	if ( 'foo' === $meta_key ) {
   		// Always return an array with your return value.
   		return array( 'bar' );
   	}
   
   	return $check; // Go on with the normal execution in meta.php
   }

   • You shouldn’t return null if the checks don’t pass, return $value. otherwise another filter with higher priority will not be able to set the value: add_filter( 'get_user_metadata', 'otherplugin_get_foo', 10, 4 ); function otherplugin_get_foo( $value, $object_id, $meta_key, $single ) { if ( 'foo' == $meta_key ) { return array( 'bar' ); } return $value; // CORRECT if $value is null it will return null, if another plugin has already used the same filter to set a value it will return that value; } add_filter( 'get_user_metadata', 'myplugin_get_baz', 10, 4 ); function otherplugin_get_foo( $value, $object_id, $meta_key, $single ) { if ( 'baz' == $meta_key ) { return array( 'bar' ); } return null; // WRONG! THIS WILL OVERRIDE ALL PREVIOUS get_{$meta_type}_metadata FILTERS; } Now if you call get_user_meta(1, ‘foo’, true); you will always get null, because myplugin_get_baz will override the $value (bar) set by the first otherplugin_get_foo filter. Always return the first parameter if you’re not going to edit the value.

     gorgdesign 4 years ago