10

I've used Advanced Custom Fields to create custom fields for Competition name, answers etc. I've made a custom post type for competitions as shown on the image and I used Wordpress functions.php to create the columns from my custom fields values.

I'm trying to get a "Filter by"-dropdown box with the competitions different names/labels like shown below, but I can only find solutions using taxonomies, which I rather not use if possible because I've only used custom fields for everything else.

Is it possible to make a custom "Filter by" dropdown using only custom fields?

Wordpress filter by

  • You can make use of the restrict_manage_posts action hook to add additional dropdown boxes. Don't forget that you'd also have to add some logic for the filter though, as WP won't know what to do with it out of the box (unlike taxonomy dropdown lists, which it can automatically handle). – David Gard Dec 21 '15 at 13:41
  • As additional thought - if you wish, you can make the Name in to link within your List Table, meaning that you can filter a Competition by clicking on the name, rather than having a dropdown. – David Gard Dec 21 '15 at 15:10
12

And for displaying result for Filter then try this code

add_filter( 'parse_query', 'prefix_parse_filter' );
function  prefix_parse_filter($query) {
   global $pagenow;
   $current_page = isset( $_GET['post_type'] ) ? $_GET['post_type'] : '';

   if ( is_admin() && 
     'competition' == $current_page &&
     'edit.php' == $pagenow && 
      isset( $_GET['competition-name'] ) && 
      $_GET['competition-name'] != '') {

    $competion_name = $_GET['competition-name'];
    $query->query_vars['meta_key'] = 'competition_name';
    $query->query_vars['meta_value'] = $competition_name;
    $query->query_vars['meta_compare'] = '=';
  }
}

Change the meta key and meta value as required. I have taken "competition name as meta_key and "competition-name" as select drop down name.

  • Nice, I was feeling lazy so suggested he ask an addition question ;) – David Gard Dec 21 '15 at 15:11
  • Seems like the 2 answers are a complete answer and should be combined. – RCNeil Jul 10 '17 at 17:28
10

The restrict_manage_posts action triggers the add_extra_tablenav() function, which is how you add additional dropdowns to your desired List Table.

In the example below, we first ensure that the Post Type is correct, and then we grab all DB values stored against the competition_name key in the postmeta table (you must change the key name as required). The query is fairly basic and only checks to see if the Competition is published, takes only unique values (you don't want duplication in the dropdown) and then orders them alphabetically.

Next we check for results (no point outputting the dropdown for nothing), and then construct the options (including a defualt to show all). Finally the dropdown is output.

As stated in my comment, this isn't the end of the story though; you'll need some logic to tell the List Table to only show your desired results when the filter is active, but I'll leave you to have a look at that and then start another question if you require further assistance. Hint - check out the file /wp-admin/includes/class-wp-posts-list-table.php, and it's parent .../wp-class-list-table.php

/**
 * Add extra dropdowns to the List Tables
 *
 * @param required string $post_type    The Post Type that is being displayed
 */
add_action('restrict_manage_posts', 'add_extra_tablenav');
function add_extra_tablenav($post_type){

    global $wpdb;

    /** Ensure this is the correct Post Type*/
    if($post_type !== 'competition')
        return;

    /** Grab the results from the DB */
    $query = $wpdb->prepare('
        SELECT DISTINCT pm.meta_value FROM %1$s pm
        LEFT JOIN %2$s p ON p.ID = pm.post_id
        WHERE pm.meta_key = "%3$s" 
        AND p.post_status = "%4$s" 
        AND p.post_type = "%5$s"
        ORDER BY "%3$s"',
        $wpdb->postmeta,
        $wpdb->posts,
        'competition_name', // Your meta key - change as required
        'publish',          // Post status - change as required
        $post_type
    );
    $results = $wpdb->get_col($query);

    /** Ensure there are options to show */
    if(empty($results))
        return;

    // get selected option if there is one selected
    if (isset( $_GET['competition-name'] ) && $_GET['competition-name'] != '') {
        $selectedName = $_GET['competition-name'];
    } else {
        $selectedName = -1;
    }

    /** Grab all of the options that should be shown */
    $options[] = sprintf('<option value="-1">%1$s</option>', __('All Competitions', 'your-text-domain'));
    foreach($results as $result) :
        if ($result == $selectedName) {
            $options[] = sprintf('<option value="%1$s" selected>%2$s</option>', esc_attr($result), $result);
        } else {
            $options[] = sprintf('<option value="%1$s">%2$s</option>', esc_attr($result), $result);
        }
    endforeach;

    /** Output the dropdown menu */
    echo '<select class="" id="competition-name" name="competition-name">';
    echo join("\n", $options);
    echo '</select>';

}
  • When using this, I get the error Notice: wpdb::prepare was called incorrectly. The query does not contain the correct number of placeholders (6) for the number of arguments passed (5). Please see Debugging in WordPress for more information. (This message was added in version 4.8.3.) in /[...]/wp-includes/functions.php on line 4773 – rassoh Jul 10 at 11:28
0

If this isn't working for anyone, my solution was needing to add the Column I was trying to filter by to the list of Sortable columns for my custom post type.

// Make Custom Post Type Custom Columns Sortable
function cpt_custom_columns_sortable( $columns ) {

    // Add our columns to $columns array
    $columns['item_number'] = 'item_number';
    $columns['coat_school'] = 'coat_school'; 

    return $columns;
} add_filter( 'manage_edit-your-custom-post-type-slug_sortable_columns', 'cpt_custom_columns_sortable' );

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