delete_post_meta( int $post_id, string $meta_key, mixed $meta_value = ” ): bool

User Contributed Notes

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   Codex 9 years ago

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   Other Examples
   Let’s assume we had a plugin that added some meta values to posts, but now when we are uninstalling the plugin, we want to delete all the post meta keys that the plugin added. Assuming the plugin added the keys related_posts and post_inspiration.

   To delete all the keys use delete_post_meta_by_key( $post_meta_key ). This would be added to the “uninstall” function:

   <?php delete_post_meta_by_key( 'related_posts' ); ?>

   Or, if you wanted to delete all the keys except where post_inspiration was “Sherlock Holmes”:

   <?php
   $allposts = get_posts( 'numberposts=-1&post_type=post&post_status=any' );
   
   foreach( $allposts as $postinfo ) {
   	delete_post_meta( $postinfo->ID, 'related_posts' );
   	$inspiration = get_post_meta( $postinfo->ID, 'post_inspiration' );
   	foreach( $inspiration as $value ) {
   		if( 'Sherlock Holmes' !== $value )
   			delete_post_meta( $postinfo->ID, 'post_inspiration', $value );
   	}
   }
   ?>

   Or maybe post number 185 was just deleted, and you want to remove all related_posts keys that reference it:

   <?php
     $allposts = get_posts( 'numberposts=-1&post_type=post&post_status=any' );
   
     foreach( $allposts as $postinfo ) {
       delete_post_meta( $postinfo->ID, 'related_posts', '185' );
     }
   ?>
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   Codex 9 years ago

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   Default Usage

   <?php delete_post_meta(76, 'my_key', 'Steve'); ?>
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   Michelle Blanchette 5 years ago

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   Be VERY careful when using this function to delete a specific key-value pair. As stated in delete_metadata()‘s documentation, providing an empty string for $meta_value will cause the check to be skipped entirely, resulting in all keys being deleted!

   $meta_value …If specified, only delete metadata entries with this value. Otherwise, delete all entries with the specified meta_key…

   To avoid accidentally deleting ALL key instances, use a short-circuit check:

   $value_to_delete = My_Class::get_value(); // may return empty string
   if ( $value_to_delete != '' && delete_metadata( 'post', 27, 'key', $value_to_delete ) ) {
    // the key-value pair was safely deleted
   }
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   Pacicio 2 years ago

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   If you want to delete all entries with a specified meta_key, regardless of the field value, you need to set meta_value as null, otherwise the function will return false and the field does not get deleted

   delete_post_meta( $post_id, $meta_key, null )