Parse query filter in wordpress and relation

Question

I am having this code in filter backend.Three filters are there. Each are working separate good. but when i run all filter same time its returning "OR" result. I need to make all three filters "AND"

add_filter( 'parse_query', 'wpse45436_posts_filter' );
function wpse45436_posts_filter( $query ){
    global $pagenow;
    $type = 'lessons';

    if (isset($_GET['post_type'])) {
        $type = $_GET['post_type'];
    }
    if ( 'lessons' == $type && is_admin() && $pagenow=='edit.php' && isset($_GET['age_band']) && $_GET['age_band'] != '') {
       // die("here");
        $query->query_vars['meta_key'] = 'dt_age_group';
        $query->query_vars['meta_value'] = $_GET['age_band'];
    }
}
add_filter( 'parse_query', 'wpse45437_posts_filter' );
function wpse45437_posts_filter( $query ){
    global $pagenow;
    $type = 'lessons';
    if (isset($_GET['post_type'])) {
        $type = $_GET['post_type'];
    }
    if ( 'lessons' == $type && is_admin() && $pagenow=='edit.php' && isset($_GET['module_no']) && $_GET['module_no'] != '') {
        $ar = array("A"=>"4-5","B"=>"6-7","C"=>"8-9","D"=>"10-11","E"=>"12-13","F"=>"14-15");
        $ar = array_flip($ar);
        $chr = array("A","B","C","D","E","F");
        $mod_no = $_GET['module_no'];
        if ( 'lessons' == $type && is_admin() && $pagenow=='edit.php' && isset($_GET['age_band']) && $_GET['age_band'] != '') {
       // die("here");
       $mod_no = $mod_no.$ar[$_GET['age_band']];
    }
        $query->query_vars['meta_key'] = 'dt_module_no';
        $query->query_vars['meta_value'] = $mod_no;
         $query->query_vars['meta_compare'] = 'LIKE';
    }
}
add_filter( 'parse_query', 'wpse45438_posts_filter' );
function wpse45438_posts_filter( $query ){
    global $pagenow;
    $type = 'lessons';

    if (isset($_GET['post_type'])) {
        $type = $_GET['post_type'];
    }
    if ( 'lessons' == $type && is_admin() && $pagenow=='edit.php' && isset($_GET['lesson_no']) && $_GET['lesson_no'] != '') {
       // die("here");
        $query->query_vars['meta_key'] = 'dt_lesson_no';
        $query->query_vars['meta_value'] = $_GET['lesson_no'];
        $query->query_vars['meta_relation'] = 'AND';
    }
}

Answer 1

Since you are querying for multiple meta_key's, you will want to put your meta_key queries in an array. A good example is this posting on StackExchange.

For each of your functions you'll want to replace the last three lines where you set the ['meta_key'], ['meta_value'], and ['meta_relation'] with something like this:

if( ! isset($query->query_vars['meta_query']) ) {
   $query->query_vars['meta_query'] = array();
   }
// setup this functions meta values
$meta = array (
   'key'  =>   'dt_module_no',
   'value' =>   $mod_no,
   'compare' => 'LIKE'
 );
 // append to meta_query array
 $query->query_vars['meta_query'][] = $meta;

By default each array in the meta_query will be 'AND'ed in the query.

This code is untested.