[Dynamic Attachment Export Elements] Output separate attachment elements per-attachment.

dynamic-attachment-export-elements.md

This snippet finds the post with the most attachments in the database, then outputs and populates those in the export columns.

The snippet will need to be adjusted if you want it to only output attachments that are images.

function wpae_output_attachment_headers( $headers, $export_id ) { 
    global $wpdb;
    $sql = "SELECT `ID`, `post_parent`, COUNT(*)
    FROM `wp_posts`
    WHERE `post_type` = 'attachment'
    GROUP BY `post_parent`
    HAVING COUNT(*) > 1
    LIMIT 50";
    
    $result = $wpdb->get_row( $sql );
    if ( ! empty( $result ) ) {
        $result = json_decode( json_encode( (array) $result ), 1 );
        
        for ( $i = 0; $i < $result["COUNT(*)"]; $i++ ) {
            $field_name = 'attachment_url_' . $i;
            $headers[]  = $field_name;
        }
    }
    return $headers;
}

function wpae_output_attachment_data( $articles, $options, $export_id ) {
    global $wpdb;
    
    foreach ( $articles as $key => $article ) {
        $sql     = "SELECT `ID` from `{$wpdb->prefix}posts` WHERE `post_parent` = '" . $article['ID'] . "' AND `post_type` = 'attachment'";
        $results = $wpdb->get_results( $sql );
        
        if ( ! empty( $results ) ) {
            for ( $i = 0; $i < count( $results ); $i++ ) {
                $ikey                            = $i;
                $field_name                      = 'attachment_url_' . $i;
                $img_url                         = wp_get_attachment_url( $results[ $ikey ]->ID );
                $articles[ $key ][ $field_name ] = $img_url;
            }
        }
    }
    return $articles; // Return the array of records to export
}

add_filter( 'wp_all_export_csv_headers', 'wpae_output_attachment_headers', 10, 2 );
add_filter( 'wp_all_export_csv_rows', 'wpae_output_attachment_data', 10, 3 );