Wordpress: Using WP_Query to get attachment returns empty set

Question

I would like to get the first audio file in the media library filtered by a custom field, but it always returns an empty set of posts. I know that I have to pass 'post_status' => 'inherit' and 'post_type' => 'attachment' , but it doesn't change anything.

<?php
    // Arguments
    $args = array(
        'post_type' => 'attachment', 
        'post_status' => 'inherit', 
        'post_mime_type' => 'audio', 
        'meta_key' => 'my_meta_key', 
        'meta_value' => 'my_meta_value', 
        'posts_per_page' => 1 );

    // Create the query
    $audio_files = new WP_Query( $args );

    // Output
    var_dump( $audio_files );    // the number of found posts is always 0

?>

So I tried to minimise it by letting away all the meta-key-stuff and searched for any attachment (as mentioned here )

<?php
    // Arguments
    $args = array(
        'post_type' => 'attachment', 
        'post_status' => 'inherit' );   // or "any", but without effect

    // Create the query
    $any_files = new WP_Query( $args );

    // Output
    var_dump( $any_files );    // same: the number of found posts is always 0
?>

So I tried it the old-fashioned way by a custom SQL-statement:

<?php
    // Get row by custom SQL-statement
    $wpdb->get_row( 'SELECT * FROM ' . $wpdb->prefix . 'posts p, ' . $wpdb->prefix .  'postmeta m WHERE p.post_mime_type LIKE "audio/%" AND p.ID = m.post_ID AND m.meta_key = "my_meta_key" AND m.meta_value = "my_meta_value" ORDER BY p.post_date DESC' );
?>

And tataaaa! I get my first audio file.

I know there are similar questions:

• Broken? WP_Query and “attachment” as a post type
• WP_Query not working as expected for attachments and custom meta_query

But neither of them helped me, even though they were treating quite the same topic.

What I am missing here? I would like to use WP_Query .

Answer 1

you should use offset,orderby and order when you are using posts_per_page it should definitely work. here is your revised code

if posts_per_page is -1 then it will list all post so in that case offset is ignored but in all other case you should use.

 $args = array(
        'post_type' => 'attachment', 
        'post_status' => 'inherit', 
         'offset'         => $offset,
        'post_mime_type' => 'audio', 
        'meta_key' => 'my_meta_key', 
         'orderby' =>'ID',
        'order'  => 'ASC',
        'meta_value' => 'my_meta_value', 
        'posts_per_page' => 1 );