Custom post type, custom taxonomy, query posts only from taxonomy (children of)

Question

I have a custom post type (portfolio-type) with a custom hierarchical taxonomy (portfolio-category)

Now I would like to query only posts from potrfolio-type, so i do:

$paged = 1;
if ( get_query_var('paged') ) $paged = get_query_var('paged');
if ( get_query_var('page') ) $paged = get_query_var('page');
query_posts( '&post_type=portfolio-type&paged=' . $paged );

And till here, everything works great. Now, I would like to query only posts, that are in any, of children custom taxonomy "categories" of a custom taxonomy category with given ID.

So I tried:

$paged = 1;
if ( get_query_var('paged') ) $paged = get_query_var('paged');
if ( get_query_var('page') ) $paged = get_query_var('page');
$query_args = array(
    'post_type' => 'portfolio-type',
    'cat' => $CAT_ID,
    'paged' => $paged,  
);
query_posts( $query_args );

Failed (no results), but I understand Why. those posts are not in standard category, but in custom taxonomy's category, so looking at wp Codex, this is what I came with:

$query_args = array(
    'post_type' => 'portfolio-type',
    'paged' => $paged,
    'tax_query' => array(
        'taxonomy' => 'portfolio-category',
        'field' => 'id',
        'terms' => $CAT_ID
    )
);

Failed again, but this time all custom posts from portfolio-type post_type displays (tax_query doesnt work, whatever ID i put there result is all the same)

What am I missing?

Answer 1

The problem was in not reading documentation carefully enough ;)

As it stands in http://codex.wordpress.org/Class_Reference/WP_Query in 'tax_query' part, "tax_query takes an array of tax query arguments arrays" so the correct part of code would be:

$query_args = array(
    'post_type' => 'portfolio-type',
    'paged' => $paged,
    'tax_query' => array(
        array(
            'taxonomy' => 'portfolio-category',
            'field' => 'id',
            'terms' => $CAT_ID
        )       
    ),
);

The missing array() in existing array() was a problem. Thanks hakre :).