Following the approach in the developer docs for selected() but can't get it to work with a custom field in the media library for a select list.

It won't save the value, or become "selected". Looks like WP is doing some js/ajax in the background here, so do I need to approach this differently or have a dumb typo?

Please see code below, help is appreciated.

/*
Add license field to media attachments 
*/

    function add_custom_field_license( $form_fields, $post ) {
        $license_field = get_post_meta($post->ID, 'license_field');
        $form_fields['license_field'] = [
            'label' => 'License',
            'input' => 'html',
            'html' => "<select name='attachments[{$post->ID}][license_field]' id='attachments-{$post->ID}-license_field'> 
        <option value='none' " . selected($license_field, "none") . ">None (all rights reserved)</option>
        <option value='CC0' " . selected($license_field, "CC0") . ">CC0</option>
        <option value='CC BY' " . selected($license_field, "CC BY") . ">CC BY</option>
        </select>",
        ];
        return $form_fields;
    }
    add_filter('attachment_fields_to_edit', 'add_custom_field_license', null, 2); 



/*
Save license field to media attachments
*/
function save_custom_field_license($post, $attachment) {  
    if( isset($attachment['license_field']) ){  
        update_post_meta($post['ID'], 'license_field', sanitize_text_field( $attachment['license_field'] ) );  
    }else{
         delete_post_meta($post['ID'], 'license_field' );
    }
    return $post;  
}
add_filter('attachment_fields_to_save', 'save_custom_field_licenser', null, 2);

Following the approach in the developer docs for selected() but can't get it to work with a custom field in the media library for a select list.

It won't save the value, or become "selected". Looks like WP is doing some js/ajax in the background here, so do I need to approach this differently or have a dumb typo?

Please see code below, help is appreciated.

/*
Add license field to media attachments 
*/

    function add_custom_field_license( $form_fields, $post ) {
        $license_field = get_post_meta($post->ID, 'license_field');
        $form_fields['license_field'] = [
            'label' => 'License',
            'input' => 'html',
            'html' => "<select name='attachments[{$post->ID}][license_field]' id='attachments-{$post->ID}-license_field'> 
        <option value='none' " . selected($license_field, "none") . ">None (all rights reserved)</option>
        <option value='CC0' " . selected($license_field, "CC0") . ">CC0</option>
        <option value='CC BY' " . selected($license_field, "CC BY") . ">CC BY</option>
        </select>",
        ];
        return $form_fields;
    }
    add_filter('attachment_fields_to_edit', 'add_custom_field_license', null, 2); 



/*
Save license field to media attachments
*/
function save_custom_field_license($post, $attachment) {  
    if( isset($attachment['license_field']) ){  
        update_post_meta($post['ID'], 'license_field', sanitize_text_field( $attachment['license_field'] ) );  
    }else{
         delete_post_meta($post['ID'], 'license_field' );
    }
    return $post;  
}
add_filter('attachment_fields_to_save', 'save_custom_field_licenser', null, 2);

• custom-field
• attachments
• media-library
• attachment-fields-to-edit

• 1 you've got an extra 'r' there on save_custom_field_licenser in the second add_filter() – mozboz Commented Jul 10, 2020 at 0:37
• And it would make sense that if it doesn't save then it doesn't have a value in the db from which to render the select, unless you manually inserted it somehow, so maybe selected() will work if that was all it was – mozboz Commented Jul 10, 2020 at 0:39
• 1 replace the define to thisadd_filter('attachment_fields_to_save', 'save_custom_field_license', null, 2); – RachC Commented Jul 10, 2020 at 0:47
• 1 In addition to correcting the typo ("licenser"), you should set the 3rd parameter for get_post_meta() to true (to get a single value), and the 3rd parameter for selected() to false (to not echo the attribute). – Sally CJ Commented Jul 10, 2020 at 1:55

1 Answer 1

As per outlined in the comments, by fixing a typo in my save function, and setting the third parameter in get_post_meta() to true, and false in selected() it worked liked a charm. Thanks everyone!

Here's the working code in case anyone is trying to add a select list custom field to their media manager:

   /*
    Add license field to media attachments 
    */
    
    function add_custom_field_license( $form_fields, $post ) {
        $license_field = get_post_meta($post->ID, 'license_field', true);
        $form_fields['license_field'] = [
            'label' => 'License',
            'input' => 'html',
            'html' => "<select name='attachments[{$post->ID}][license_field]' id='attachments-{$post->ID}-license_field'> 
        <option value='none' " . selected($license_field, "none", false) . ">None (all rights reserved)</option>
        <option value='CC0' " . selected($license_field, "CC0", false) . ">CC0</option>
        <option value='CC BY' " . selected($license_field, "CC BY", false) . ">CC BY</option>
        <option value='CC BY-NC' " . selected($license_field, "CC BY-NC", false) . ">CC BY-NC</option>
        <option value='CC BY-SA' " . selected($license_field, "CC BY-SA", false) . ">CC BY-SA</option>
        <option value='CC BY-NC-ND' " . selected($license_field, "CC BY-NC-ND", false) . ">CC BY-NC-ND</option>
        </select>",
        ];
        return $form_fields;
    }
    add_filter('attachment_fields_to_edit', 'add_custom_field_license', null, 2); 
     
    /*
    Save license field to media attachments
    */

    function save_custom_field_license($post, $attachment) {  
        if( isset($attachment['license_field']) ){  
            update_post_meta($post['ID'], 'license_field', sanitize_text_field( $attachment['license_field'] ) );  
        }else{
             delete_post_meta($post['ID'], 'license_field' );
        }
        return $post;  
    }
    add_filter('attachment_fields_to_save', 'save_custom_field_license', null, 2);