Passing an array into WP_Query as a variable

Question

I am trying to dynamically create a meta query based upon an array of post_id values. However, the query is not working. I have used var_dump() to see $meta_array, and it appears to be a standard array in the correct format to pass into WP_Query().

$post_id_array = array( "12", "24" ); //this array will be dynamically generated
$meta_array = array();
foreach ($post_ids_array as $key => $value) {
    array_push($meta_array,
        array(
            'key' => 'relate_blog_posts',
            'value' => $value,
            'compare' => 'LIKE'
        )
    );
}

$post_args = array(
    'post_type' => 'post',
    'posts_per_page' => 3,
    'post_status' => 'publish',
    'meta_query' => array($meta_array)
 );
$post_query = new WP_Query($post_args);

Please let me know if I have made a mistake, or am simply going about this the wrong way.

Thanks!

Answer 1

First of all, you have a typo in your code. The variable with post IDs is called post_id_array, but your foreach loop uses post_ids_array (ids instead of id).

When you fix this, then there's one more problem. Meta query param should be an array of queries and each query should be an array. But your $post_args generated by your code looks like this:

array(4) {
  ["post_type"]=>
  string(4) "post"
  ["posts_per_page"]=>
  int(3)
  ["post_status"]=>
  string(7) "publish"
  ["meta_query"]=>
  array(1) {
    [0]=>
    array(2) {
      [0]=>
      array(3) {
        ["key"]=>
        string(17) "relate_blog_posts"
        ["value"]=>
        string(2) "12"
        ["compare"]=>
        string(4) "LIKE"
      }
      [1]=>
      array(3) {
        ["key"]=>
        string(17) "relate_blog_posts"
        ["value"]=>
        string(2) "24"
        ["compare"]=>
        string(4) "LIKE"
      }
    }
  }
}

As you can see, meta_query is an array containing an array containing queries.

And here is your code with all the fixes:

$post_ids_array = array( "12", "24" ); //this array will be dynamically generated
$meta_array = array();
foreach ($post_ids_array as $key => $value) {
    array_push($meta_array,
        array(
            'key' => 'relate_blog_posts',
            'value' => $value,
            'compare' => 'LIKE'
        )
    );
}

$post_args = array(
    'post_type' => 'post',
    'posts_per_page' => 3,
    'post_status' => 'publish',
    'meta_query' => $meta_array
);
$post_query = new WP_Query($post_args);

Answer 2

With the help of @Krzysiek Dróżdż I have found the solution to this issue. My first issue was that I was nesting the $meta_array in another array.

As suggested by @Krzysiek, I changed this line

'meta_query' => array($meta_array)

to

'meta_query' => $meta_array

. This allowed for the meta array to remain in the correct syntax for the WP_Query object. The final issue that I resolved was that in a meta query with multiple values, you must define how the values are related. For instance

'meta_query' => array(
        array (
           'key' => 'relate_blog_posts',
           'value' => '155',
           'compare' => 'LIKE'
        ),
        array (
           'key' => 'relate_blog_posts',
           'value' => '156',
           'compare' => 'LIKE'
        )
    )

will not return any values, while the following will:

'meta_query' => array(
        'relation' => 'OR',
        array (
           'key' => 'relate_blog_posts',
           'value' => '155',
           'compare' => 'LIKE'
        ),
        array (
           'key' => 'relate_blog_posts',
           'value' => '156',
           'compare' => 'LIKE'
        ),
    )

Thus by initially defining $meta_array to include the 'relation' attribute, the final array was in the proper syntax and the query worked. Final working code:

$post_ids_array = array( "12", "24" ); //this array will be dynamically generated
$meta_array = array('relation'=>'OR');
foreach ($post_ids_array as $key => $value) {
    array_push($meta_array,
        array(
            'key' => 'relate_blog_posts',
            'value' => $value,
            'compare' => 'LIKE'
        )
    );
}

$post_args = array(
    'post_type' => 'post',
    'posts_per_page' => 3,
    'post_status' => 'publish',
    'meta_query' => $meta_array
);
$post_query = new WP_Query($post_args);