Filters post in admin with dropdown select, custom post type

Question

I'm trying to filter my post in my admin area with a custom filter dropdown.

I use this method to make it: https://wordpress.stackexchange.com/a/45447/84541

Here is my code:

   add_action( 'restrict_manage_posts', 'wpse45436_admin_posts_filter_restrict_manage_posts' );

    function wpse45436_admin_posts_filter_restrict_manage_posts(){
        $type = 'post';
        if (isset($_GET['post_type'])) {
            $type = $_GET['post_type'];
        }

        //only add filter to post type you want

        if ('post' == $type){
            //change this to the list of values you want to show
            //in 'label' => 'value' format
            $values = array();
            $testting = get_posts(array('posts_per_page'=>-1, 'post_type'=>'edition'));
            foreach($testting as $post):
                $values[$post->post_title] = $post->ID;


            endforeach; 


            ?>

            <select name="ADMIN_FILTER_FIELD_VALUE">
            <option value=""><?php _e('Toutes les éditions ', 'wose45436'); ?></option>
            <?php
                $current_v = isset($_GET['ADMIN_FILTER_FIELD_VALUE'])? $_GET['ADMIN_FILTER_FIELD_VALUE']:'';
                foreach ($values as $label => $value) {
                    printf(
                            '<option value="%s"%s>%s</option>',
                            $value,
                            $value == $current_v? ' selected="selected"':'',
                            $label
                        );
                    }
            ?>
            </select>

            <?php
        }
    }

    add_filter( 'parse_query', 'wpse45436_posts_filter' );

    function wpse45436_posts_filter( $query ){
        global $pagenow;
        $type = 'post';
        if (isset($_GET['post_type'])) {
            $type = $_GET['post_type'];
        }
        if ( 'post' == $type && is_admin() && $pagenow=='edit.php' && isset($_GET['ADMIN_FILTER_FIELD_VALUE']) && $_GET['ADMIN_FILTER_FIELD_VALUE'] != '') {
            $query->query_vars['meta_key'] = 'n_de_ldition';
            $query->query_vars['meta_value'] = $_GET['ADMIN_FILTER_FIELD_VALUE'];
        }
    }

When I click on filter after selecting my option in my dropdown select, It does filter fine but my query who was adding option in my select is empty. I can't understand what I'm doing wrong, is this because I use a get_posts to get my custom post type informations?

Here are some image. When not filtered but clicked on select dropdown:

After filtering, options from selected dropdown are no more avaible but filters has worked fine:

If I replace this:

            $values = array();
            $testting = get_posts(array('posts_per_page'=>-1, 'post_type'=>'edition'));
            foreach($testting as $post):
                $values["N°".$post->post_title] = $post->ID;


            endforeach; 

whit this:

    $values = array(
        'label' => 'value', 
        'label1' => 'value1',
        'label2' => 'value2',
    );

It works fine but I have to change my labels and my values dynamicly.

Any Idea?

Thank's in advance.

Answer 1

Thank you so much, it's working. Here is my modified code:

function wpse45436_posts_filter( $query ){
    global $pagenow;
    $type = 'post';
    if (isset($_GET['post_type'])) {
        $type = $_GET['post_type'];
    }
    if ( 
        'post' == $type  
         && is_admin()  
         && $pagenow =='edit.php'  
         && isset($_GET['ADMIN_FILTER_FIELD_VALUE']) 
         && $_GET['ADMIN_FILTER_FIELD_VALUE'] != '' 
         && $query->is_main_query()
     ) {
            $query->query_vars['meta_key'] = 'n_de_ldition';
            $query->query_vars['meta_value'] = $_GET['ADMIN_FILTER_FIELD_VALUE'];
        }
    }

By targetting the main query with $query->is_main_query() we avoid modifying our get_posts() call that we use to populate the select box. The reason is that get_posts() is just a wrapper for the WP_Query so the parse_query hook can affect it as well.