tax_query not working in template

Question

I have a custom post type called 'product' with a registered taxonomy 'product-type'.

I want to display all post from a particular taxonomy from custom post type. In my case I want to display all the posts from 'product' post type with a term of 'software'.

    <?php $args = array( 
        'post_type' => 'product', 
        'tax_query' => array(
            'taxonomy' => 'product-type',
            'terms' => array('software'),
            'field' => 'slug'
        ),
        'posts_per_page' => 9, 
        'orderby' => 'menu_order', 
        'order' => 'ASC' 
    );

    $query = new WP_Query( $args ); ?>

    <ul class="list-products clearfix">

    <?php while ( $query->have_posts() ) : $query->the_post(); ?>

This is producing me no results. It's empty.

But if I remove the entire tax_query from $arg

'tax_query' => array(
    'taxonomy' => 'product-type',
'terms' => array('software'),
'field' => 'slug'
),

Everything works fine. I get all the posts from 'product' custom post type.

Answer 1

If you look at the documentation for WP_Query taxonomy parameters, you'll see that the tax_query is an array of arrays.

So:

'tax_query' => array(
    array(
        'taxonomy' => 'product-type',
        'terms' => array('software'),
        'field' => 'slug'
     )
)

Answer 2

tax_query is an array of array, also id you use another array to specify your terms you should also specity an operator. So your $args should be something like this:

 $args = array( 
      'post_type' => 'product', 
      'tax_query' => array(
         array(
           'taxonomy' => 'product-type',
           'terms' => array('software'),
           'field' => 'slug',
           'operator' => 'IN'
         )
       ),
      'posts_per_page' => 9, 
      'orderby' => 'menu_order', 
      'order' => 'ASC'
    );

Hope it helps!