What is the best way to reset a search on a meta_key / meta_value?

Question

I’ve build several search forms with different <select> and <input>.

I use a meta_query and build an array of key/value pair.

Array
(
    [relation] => AND
    [0] => Array
        (
            [relation] => AND
            [0] => Array
                (
                    [fields] => ID
                    [key] => ville
                    [value] => Angers
                    [compare] => LIKE
                    [type] => CHAR
                )

        )

    [1] => Array
        (
            [relation] => OR
        )

    [2] => Array
        (
            [relation] => OR
        )

)

It works, i can filter users or posts (i use WP_User_Query or WP_Query).

The search form is using AJAX, it means that each time a user change a select, the $query_array is updated and the list of results is also updated.

So, let’s say the default value of a select is 0

<option selected="" value="0"> -- City -- </option>

In this case, i reset the meta_key / meta_value :

if (!empty($_POST['city']) && $_POST['city'] != '0') {

        $meta_value_ville = $_POST['city'];
        array_push($query_array_and, array('fields' => 'ID', 'key' => 'ville', 'value' => $meta_value_ville, 'compare' => 'LIKE', 'type' => 'CHAR'));
    } else if ($_POST['city'] === '0') {
        // reset
        array_push($query_array_and, array('fields' => 'ID', 'key' => '', 'value' => '', 'compare' => 'LIKE', 'type' => 'CHAR'));
    }

I empty the key and the value.

The result is

Array
(
    [relation] => AND
    [0] => Array
        (
            [relation] => AND
            [0] => Array
                (
                    [fields] => ID
                    [key] => 
                    [value] => 
                    [compare] => LIKE
                    [type] => CHAR
                )

        )

    [1] => Array
        (
            [relation] => OR
        )

    [2] => Array
        (
            [relation] => OR
        )

)

Is it the best way to do it ? I feel that sometime the list of posts or users is not complete with this method.

Answer 1

I wouldn't push the meta query entries like that but build it more logical.

So for example:

$meta_query_args = array( 'relation' => 'AND' ); // assuming you want 'AND' search, you're using both in your example

if ( ! empty( $_POST['city'] ) && $_POST['city'] != '0' ) {

    $meta_value_ville = $_POST['city'];

    $meta_query_args['city_clause'] = array(
        'key'     => 'ville',
        'value'   => $meta_value_ville,
        'compare' => 'LIKE',
        'type'    => 'CHAR'
    );
}

// Example, say you also have a country field
if ( ! empty( $_POST['country'] ) && $_POST['country'] != '0' ) {

    $meta_value = $_POST['country'];

    $meta_query_args['country_clause'] = array(
        'key'     => 'country',
        'value'   => $meta_value,
        'compare' => 'LIKE',
        'type'    => 'CHAR'
    );
}

Note 1: I'm no longer pushing date into existing arrays build build it from scratch every time. This saves you all the code of resetting certain meta query arrays.

Note 2: I removed the 'fields' => 'ID' part since this isn't part of the meta_query. You should add this to the WP_Query.

Note 3: Because I'm giving the clauses named index (e.g. city_clause) you can use them in the rest of your WP_Query. Example: You can sort on them now like this:

$q = new WP_Query( array(
    'meta_query' => $meta_query_args,
    'orderby'    => 'city_clause'
) );