The code you see below only works sometimes. I'm no pro on PHP so can anyone help me improve this code? I use it in my functions-php file in my WordPress mu setup.

The biggest problem is that it won't remove duplicate fileds. i.e. if I have 2 custom fields named Image and one is empty I want this script to remove this empty field, but it doesn't work

add_action('save_post','my_cf_check');
function my_cf_check($post_id) {

    // verify this is not an auto save routine. 
    if ( defined('DOING_AUTOSAVE') && DOING_AUTOSAVE ) return;

    //authentication checks
    if (!current_user_can('edit_post', $post_id)) return;

    //obtain custom field meta for this post
     $custom_fields = get_post_custom($post_id);

    if(!$custom_fields) return;

    foreach($custom_fields as $key=>$custom_field):
        //$custom_field is an array of values associated with $key - even if there is only one value. 
        //Filter to remove empty values.
        //Be warned this will remove anything that casts as false, e.g. 0 or false 
        //- if you don't want this, specify a callback.
        //See php documentation on array_filter
        $values = array_filter($custom_field);

        //After removing 'empty' fields, is array empty?
        if(empty($values)):
            delete_post_meta($post_id,$key); //Remove post's custom field
        endif;
    endforeach; 
    return;
} 

The code you see below only works sometimes. I'm no pro on PHP so can anyone help me improve this code? I use it in my functions-php file in my WordPress mu setup.

The biggest problem is that it won't remove duplicate fileds. i.e. if I have 2 custom fields named Image and one is empty I want this script to remove this empty field, but it doesn't work

add_action('save_post','my_cf_check');
function my_cf_check($post_id) {

    // verify this is not an auto save routine. 
    if ( defined('DOING_AUTOSAVE') && DOING_AUTOSAVE ) return;

    //authentication checks
    if (!current_user_can('edit_post', $post_id)) return;

    //obtain custom field meta for this post
     $custom_fields = get_post_custom($post_id);

    if(!$custom_fields) return;

    foreach($custom_fields as $key=>$custom_field):
        //$custom_field is an array of values associated with $key - even if there is only one value. 
        //Filter to remove empty values.
        //Be warned this will remove anything that casts as false, e.g. 0 or false 
        //- if you don't want this, specify a callback.
        //See php documentation on array_filter
        $values = array_filter($custom_field);

        //After removing 'empty' fields, is array empty?
        if(empty($values)):
            delete_post_meta($post_id,$key); //Remove post's custom field
        endif;
    endforeach; 
    return;
} 

• posts
• custom-field

• 1 What is the main idea of the code? Provide some explanation on what it's supposed to do. – Webord Commented Feb 20, 2012 at 9:12

2 Answers 2

I believe this was my solution to a previous question you had.

I mentioned in that answer that the code didn't deal with the eventuality of a key with multiple values and only some of which are empty. The reason why is how WordPress treats delete_post_meta...

When using delete_post_meta, the first two arguments specify the post and the key of the custom field. You have a third optional argument, which can be used to specify a key-value pair. So...

//Delete all post meta with key $key    
delete_post_meta($post_id,$key)
//Delete all post meta with key $key AND value $value
delete_post_meta($post_id,$key,$value)

The problem is that if $value is empty it treats it like the first case and deletes all post meta for that post and key.

There is a workaround (and perhaps a non-WordPress based one would be more efficient here), the logic is as follows;

• Identify a key with an empty-value
• Retrieve all non-empty values
• Delete the key
• Re-insert the key, adding only non-empty values

The edited foreach loop;

foreach($custom_fields as $key=>$values):
    //$values is an array of values associated with $key - even if there is only one value. 
    //Filter to remove empty values.
    //Be warned this will remove anything that casts as false, e.g. 0 or false 
    //- if you don't want this, specify a callback.
    //See php documentation on array_filter
    $nonemptyvalues = array_filter($values);

    //If the $nonemptyvalues doesn't match $values then we removed an empty value(s).
    if($nonemptyvalues!=$values):
         //delete key
         delete_post_meta($post_id,$key);

         //re-add key and insert only non-empty values
         foreach($nonemptyvalues as $nonemptyvalue){
             add_post_meta($post_id,$key,$nonemptyvalue);
         }
    endif;  
endforeach;

The above is untested

See what you think of this:

add_action('save_post','my_cf_check');
function my_cf_check($post_id) {

    // verify this is not an auto save routine. 
    if ( defined('DOING_AUTOSAVE') && DOING_AUTOSAVE ) return;

    //authentication checks
    if (!current_user_can('edit_post', $post_id)) return;

    //obtain custom field meta for this post
    $custom_fields = get_post_custom($post_id);

    if( !$custom_fields ) return;

    foreach ( $custom_fields as $key => $val_arr ):

        if ( empty($val_arr) )
            delete_post_meta($post_id, $key); // if it's empty, delete the field.

        elseif ( is_array($val_arr) && 1 < count($val_arr) ) {

            foreach ($val_arr as $value) {
                // check each value, and delete the post meta if it's empty
                if ( empty( $value ) )
                    delete_post_meta($post_id, $key, $value);

            }

        } else {
            // it's an array with a single non-empty value, or it's a non-empty string
        }

    endforeach;

}