WordPress:Function Reference/post meta Function Examples

Description

The following is a detailed example for the usage of the add_post_meta, delete_post_meta, update_post_meta, and get_post_meta functions.

Example

%%%<?php /******************* This function handles the mood and listening_to meta tags. It can be called with an action of update, delete, and get (default) When called with an action of update, either $mood or $listening_to must be provided. ie. mood_music( $post->ID, 'update', 'Happy', 'Bon Jovi - It's My Life' );

• • • • • • • • • • • • • • • • • • • /

function mood_music( $post_id, $action = 'get', $mood = 0, $listening_to = 0 ) {

 //Let's make a switch to handle the three cases of 'Action'
 switch ($action) {
   case 'update' :
     if( ! $mood && ! $listening_to )
       //If nothing is given to update, end here
       return false;
     
     //add_post_meta usage:
     //add_post_meta( $post_id, $meta_key, $meta_value, $unique = false )
     
     //If the $mood variable is supplied,
     //add a new key named 'mood', containing that value.
     //If the 'mood' key already exists on this post,
     //this command will simply add another one.
     if( $mood ) {
       add_post_meta( $post_id, 'mood', $mood );
       return true;
       }
     //update_post_meta usage:
     //update_post_meta( $post_id, $meta_key, $meta_value )
     
     //If the $listening_to variable is supplied,
     //add a new key named 'listening_to', containing that value.
     //If the 'listening_to' key already exists on this post,
     //this command will update it to the new value
     if( $listening_to ) {
       add_post_meta( $post_id, 'listening_to', $listening_to, true ) or
         update_post_meta( $post_id, 'listening_to', $listening_to );
       return true;
     }
   case 'delete' :
     //delete_post_meta usage:
     //delete_post_meta( $post_id, $meta_key, $prev_value = ' ' )
   
     //This will delete all instances of the following keys from the given post
     delete_post_meta( $post_id, 'mood' );
     delete_post_meta( $post_id, 'listening_to' );
     
     //To only delete 'mood' if it's value is 'sad':
     //delete_post_meta( $post_id, 'mood', 'sad' );
   break;
   case 'get' :
     //get_post_custom usage:
     //get_post_meta( $post_id, $meta_key, $single value = false )
 
     //$stored_moods will be an array containing all values of the meta key 'mood'
     $stored_moods = get_post_meta( $post_id, 'mood' );
     //$stored_listening_to will be the first value of the key 'listening_to'
     $stored_listening_to = get_post_meta( $post_id, 'listening_to', 'true' );

     //Now we need a nice ouput format, so that
     //the user can implement it how he/she wants:
     //ie. echo mood_music( $post->ID, 'get' );
     

$return = '

';

     if ( ! empty( $stored_moods ) )
       $return .= 'Current Mood: ';
     foreach( $stored_moods as $mood )
       $return .= $mood . ', ';
     $return .= '
';
     if ( ! empty( $stored_moods ) ) {
       $return .= 'Currently Listening To: ';
       $return .= $stored_listening_to;
       }

$return .= '

';

     return $return;
   default :
     return false;
   break;
 } //end switch

} //end function

?>%%%