WP_Query the same query, different syntax - one of which does not work

Question

I have WP_Query that works well:

$args = array(
'post_type' => 'product',
'meta_key'  => 'product_subtype',
'meta_value'=> 'public',
'compare'   => '='      
);

but since I want to search for several meta_keys, I tried the syntax "array":

$args = array(
'post_type' => 'product',
'meta_query' => array(                 
                  array(
                    'meta_key'     => 'product_subtype',
                    'meta_value'   => 'public',
                    'compare'      => '='
                      ),
                    ),                  
); 

but it does not work - it gives me all messages with 'post_type' = 'product' - although this is the same request. I do not know why. Can someone point out a mistake?

I fulfill the request as follows (for example, this is said in all the textbooks we found)

$the_query = new WP_Query( $args );

as I said, the first way works, and I only get products with "product_subtype = public", the second ignores the array of meta-requests. But why?

Answer 1

, WP_Query . , Codex WP_Query, , meta_query meta_.

, meta_ , .