Adding an array from a query string to a WP meta_query

Question

I am collecting values from a query string as an array. Then collecting those values and placing them into the value of the 'meta_query'.

I am having trouble where nothing gets outputted from the WP_Query. I feel like there is something wrong with the second array in the 'meta_query'.

I have tried to change the compare to 'LIKE', and that shows all the content instead of what is in the query. I also tried to remove the relation OR it has no effect on the result.

When I print out the variable, I achieve the correct array I want.

Query string:

?variable[]=value1&variable[]=value2

PHP code:

<?php
$variable_selected = $_GET['variable'];

$filter = array(
    'post_type' => 'my_custom_post_type',
    'meta_query' => array(
        'relation' => 'OR',
         array(
            'key' => 'my_post_field',
            'value' => $variable_selected,
            'compare' => 'IN'
            )
        )

    );

    $posts = new WP_Query( $filter  );

Any help on this will be great.

Answer 1

This $_GET['variable'] is an array, as per your URL query string ?variable[]=value1&variable[]=value2, $_GET['variable'][0] and $_GET['variable'][1] should return those 2 key values

Edit - after the discussion - making it dynamic

$meta_query = array();
if ( ! empty( $_GET["variable"] ) ) {
    if ( is_array( $_GET["variable"] ) ) {
        $meta_query['relation'] = 'OR';
        foreach ( $_GET["variable"] as $value ) {
            $meta_query[] = array(
                'key' => 'my_post_field',
                'value' => sanitize_text_field( (string) $value ),
                'compare' => '='
            );
        }
    } else {
        $meta_query = array(
            'key' => 'my_post_field',
            'value' => sanitize_text_field( (string) $_GET["variable"] ),
            'compare' => '='
        );
    }
}
$filter = array(
    'post_type' => 'my_custom_post_type',
    'meta_query' => array(
        'relation' => 'OR',
        $meta_query
    )
);
$posts = new WP_Query( $filter );

I have changed the operator to = because I was testing it and it worked on my local installation.

meta_compare (string) - Operator to test the 'meta_value'. Possible values are '=', '!=', '>', '>=', '<', '<=', 'LIKE', 'NOT LIKE', 'IN', 'NOT IN', 'BETWEEN', 'NOT BETWEEN', 'NOT EXISTS', 'REGEXP', 'NOT REGEXP' or 'RLIKE'. Default value is '='. — codex