I am attempting to filter results based on what the user has inputted.

function custom_archive() {
    if ( is_post_type_archive( 'profiles' ) ) {
        // if we are on a profiles archive page, edit the query according to the posted data.
        $data = $_POST['networks'];

        if ( isset( $data ) ) {
            //count the array
            if ( count( $data ) > 1 ) {
                $data = implode( ',', $data );
            } else {
                //$data = $data[0];

            //set the query to only search for whatever the user wants, eg news
            $wp_query->set( 'tax_query', array(
                    'taxonomy' => 'networks',
                    'field'    => 'id',
                    'terms'    => $data,
                    'operator' => 'IN',
            ) );
add_action( 'pre_get_posts', 'custom_archive' );

I have debugged my code and the data get's inputted correctly. Although, I get no posts back.

Are there any problems with this code? I believe the error may be elsewhere in my theme, but I do wish to check out this code so I can take it out of the equation. Cheers!

EDIT: One thing I should mention is that I have a version of this code working for my Blog page. I am trying to now get this code working for an archive, and for it to return the correct posts still within the archive page, but instead it redirects me to a Search page.

  • How does $_POST['networks'] get set? Do you have a form? Is it a select field or multi-select field? Are the values IDs or slugs? – Jacob Peattie Jul 5 '17 at 10:00
  • Yes, I have a form. The values of the checkboxes are IDs. It's a multi-select field - hence why I validate if $data is an array (to comma-separate it). – Josh Murray Jul 5 '17 at 10:02

So there's a few things wrong with the code:

  1. You're not using the query object that's passed to the pre_get_posts hook, so you're not modifying the actual query.
  2. Field is set to id instead of term_id.
  3. If you're using IN as the operator, pass an array to terms.
  4. You're not sanitizing the value of $_POST['networks']. You might be ok without it, since WordPress shouldn't let anything too nasty happen, but it's a good idea to at least ensure that the values are the correct type.

This version of the function addresses these issues:

function my_query_by_selected_networks( $query ) {
    if ( is_admin() ) {

    if ( $query->is_main_query() && $query->is_post_type_archive( 'profiles' ) ) {
        if ( isset( $_POST['networks'] ) ) {
            if ( is_array( $_POST['networks'] ) ) {
                $networks = array_map( 'intval', $_POST['networks'])
            } else {
                $networks = array( intval( $_POST['networks'] ) );

            $tax_query = $query->get( 'tax_query' ) ?: array();

            $tax_query[] = array(
                'taxonomy' => 'networks',
                'field'    => 'term_id',
                'terms'    => $networks,
                'operator' => 'IN',

            $query->set( 'tax_query', $tax_query );
add_action( 'pre_get_posts', 'my_query_by_selected_networks' );


  1. The function accepts the $query variable and uses that the update the query.
  2. It uses term_id as the value for field.
  3. $networks, the value passed to the tax query is left as an array, or made an array if $_POST['networks'] isn't already an array.
  4. It sanitizes the value of $_POST['networks'] with intval, making sure that $networks is an array of integers, which is what the tax query expects.

Additionally, I modified the tax_query code so that it doesn't entirely replace any tax queries that could be made by other plugins. It does this by checking if there's already a tax query and adding on to it if there is. This is probably unnecessary, but it's a habit of mine.

EDIT: As per Tom's suggestion I've added in $query->is_main_query(), to make sure that we're only modifying the main loop, so this doesn't go and affect things like widgets and menus etc. I also added a bit at the top to bail if we're in the admin, since we don't want to modify back-end queries.

Also, custom_archive is a very generic name for a function, and could easily be shared by other plugins or WordPress itself. It's a good idea to be more descriptive, but most importantly, you should prefix functions with something unique to your theme or plugin to avoid conflicts. In my example it's just my_. I suggest replacing it, since my_ is a common example prefix.

| improve this answer | |
  • 2
    I'll give you an upvote if you throw in an $query->is_main_query() check, bonus points if you mention the super generic function name and adding a prefix – Tom J Nowell Jul 5 '17 at 11:16

You should provide an array of id's to the tax_query - like here in the example from the docs:

'tax_query' => array(
        'taxonomy' => 'actor',
        'field'    => 'term_id',
        'terms'    => array( 103, 115, 206 ),
        'operator' => 'NOT IN',

So you could and should sanitize the values from $_POST['networks'] but shouldn't do implode which turns the array into a flat string.

| improve this answer | |
  • Thank you for your help - although, this solution never worked in my case. I have changed my question by adding more information. – Josh Murray Jul 5 '17 at 10:24
  • 1
    I would note that you should always query for what you want, querying for what you do not want is slow/expensive and involves full table scans – Tom J Nowell Jul 5 '17 at 11:14

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