I am creating a custom search form which will search a custom post type called recipes. and it has a load of taxonomies.

Now I output these taxonomy's terms into checkboxes which are grouped by the taxonomy name.

The issue is on the input:

<!-- language: lang-html -->

  <label><input type="checkbox" name="epx_recipes_season[]" value="autumn">Autumn</label>
  <label><input type="checkbox" name="epx_recipes_season[]" value="spring">Spring</label>
  <label><input type="checkbox" name="epx_recipes_season[]" value="summer-3">Summer</label>
  <label><input type="checkbox" name="epx_recipes_season[]" value="winter-3">Winter</label>

  <label><input type="checkbox" name="epx_recipes_course[]" value="breakfast-3">Breakfast</label>
  <label><input type="checkbox" name="epx_recipes_course[]" value="brunch-2">Brunch</label>
  <label><input type="checkbox" name="epx_recipes_course[]" value="dessert">Dessert</label>
  <label><input type="checkbox" name="epx_recipes_course[]" value="dinner">Dinner</label>
  <label><input type="checkbox" name="epx_recipes_course[]" value="light-meals-2">Light Meals</label>
  <label><input type="checkbox" name="epx_recipes_course[]" value="lunch-3">Lunch</label>

  <label><input type="checkbox" name="epx_recipes_requirements[]" value="diary-free">Diary free</label>
  <label><input type="checkbox" name="epx_recipes_requirements[]" value="egg-free">Egg Free</label>
  <label><input type="checkbox" name="epx_recipes_requirements[]" value="gluten-free-3">Gluten Free</label>
  <label><input type="checkbox" name="epx_recipes_requirements[]" value="nut-free">Nut Free</label>
  <label><input type="checkbox" name="epx_recipes_requirements[]" value="shellfish-free">Shellfish free</label>
  <label><input type="checkbox" name="epx_recipes_requirements[]" value="vegitarians">vegitarians</label>

  <label><input type="checkbox" name="epx_recipes_cuisines[]" value="american">American</label>
  <label><input type="checkbox" name="epx_recipes_cuisines[]" value="british-3">British</label>
  <label><input type="checkbox" name="epx_recipes_cuisines[]" value="greek-3">Greek</label>
  <label><input type="checkbox" name="epx_recipes_cuisines[]" value="irish">Irish</label>
  <label><input type="checkbox" name="epx_recipes_cuisines[]" value="italian">Italian</label>
  <label><input type="checkbox" name="epx_recipes_cuisines[]" value="mexican-3">Mexican</label>
  <label><input type="checkbox" name="epx_recipes_occastions[]" value="birthdays">Birthdays</label>
  <label><input type="checkbox" name="epx_recipes_occastions[]" value="christmas">Christmas</label>
  <label><input type="checkbox" name="epx_recipes_occastions[]" value="easter-3">Easter</label>
  <label><input type="checkbox" name="epx_recipes_occastions[]" value="fathers-day-2">Fathers Day</label>
  <label><input type="checkbox" name="epx_recipes_occastions[]" value="mothers-day-2">Mothers day</label>
  <label><input type="checkbox" name="epx_recipes_occastions[]" value="valentines">Valentines</label>

The issue comes from the name they have to keep the grouped together they have a [] so when posted it goes as array which i can then parse. this issue is WordPress is reading the form straight away and outputting the following error message.

Notice: Array to string conversion in /home/sites/epixdev1.co.uk/public_html/htk2014/wp-includes/query.php on line 1858

Warning: preg_split() expects parameter 2 to be string, array given in /home/sites/epixdev1.co.uk/public_html/htk2014/wp-includes/query.php on line 1867

Notice: Array to string conversion in /home/sites/epixdev1.co.uk/public_html/htk2014/wp-includes/query.php on line 1858

Warning: preg_split() expects parameter 2 to be string, array given in /home/sites/epixdev1.co.uk/public_html/htk2014/wp-includes/query.php on line 1867

Notice: Trying to get property of non-object in /home/sites/epixdev1.co.uk/public_html/htk2014/wp-content/plugins/wordpress-seo/frontend/class-opengraph.php on line 524

Here the code that makes the form

<!-- language: lang-php -->

//Will be used to output the advanced search box
function epix_recipes_search(){
    //Need to run each different type of taxonmies
    //How Many there are
    $noTax = 6;

    //The Taxonomies
    $taxonomies = array('epx_recipes_season','epx_recipes_course','epx_recipes_requirements','epx_recipes_cuisines','epx_recipes_occastions','epx_recipes_typeofcooking');

    //need the basic output varible 
    $output = "";

    //Need to build a basic form
    $output .= '<form method="post" id="searchform" action="/recipes/">'."\r\n";
    //Now a Basic Search box
    $output .= '    <h2>Keyword Search</h2>'."\r\n";
    $output .= '    <input type="text" class="field" name="s" id="s" size="19" placeholder="Search" />'."\r\n";

    //Now need to Show the Advance Search Area
    $output .= '    <h2>Advanced Filters</h2>'."\r\n";
    //Now need to run the system for each Taxonomies
    foreach ( $taxonomies as $tax ) {
        //Need to get the name of each TAX
        //What Taxonomy we want to check
          'name' => $tax
        $outputtype = 'objects'; // or objects
        if  ($taxonomieslist) {
            foreach ($taxonomieslist as $taxonomiesone ) {
              $output .= '  <h3>'. $taxonomiesone->labels->name. '</h3>'."\r\n";

        //now get the terms in the Taxonomies
        $output .= epix_recipes_taxterms($tax);

    //now need to end the form with the correct sytack

    //First a submit button
    $output .= '    <input type="submit" class="submit" name="submit" id="searchsubmit" value="submit" />'."\r\n";
    //Now the closing for tag
    $output .= '</form'."\r\n";

    //Need to return the form
    return $output;

  //This will get the taxonomies terms
  function epix_recipes_taxterms($tax){

    //Need to get each term and return it
    $returnoutput = "";
    $terms = get_terms($tax,'hide_empty=0');
    if ( !empty( $terms ) && !is_wp_error( $terms ) ){
        //$returnoutput .= "  <select name=".$tax.">"."\r\n";
        $i = 0;
        foreach ( $terms as $term ) {
            $returnoutput .= '      <label><input type="checkbox" name="'.$tax.'[]" value="'.$term->slug.'">' . $term->name . '</label>'."\r\n";
        //$returnoutput .= "  </select>"."\r\n";
    return $returnoutput;

If anyone can help me work out why this is happening, or a way to stop WordPress giving out these errors that would be really helpful.

Yes I have WordPress debug on!


2 Answers 2


Here's an option.
Give a more specific name e.g. custom_search_form to your submit button:

//First a submit button
$output .= '<input type="submit" class="submit" name="custom_search_form" id="searchsubmit" value="submit" />'."\r\n";

Then you can add this to your functions.php file:

add_action( 'parse_request', 'my_custom_search_form' );
function my_custom_search_form($query) {
  //return if it not our custom search form
  if ( ! isset( $query->query_vars[ 'custom_search_form' ] ) )
    return $query;

  //handle form here

Also, don't forget to set the query_var to true when registering your taxonomy:

'query_var'         => true,
  • I tried that but it still bringing up them errors, it like it reading it no matter what i do. Oct 1, 2014 at 13:28
  • I've edited my answer to change the action to "parse_request". Hope that it works for you. Oct 1, 2014 at 14:00
  • Sadly tried that did not resolve that issue, :/ Oct 2, 2014 at 6:15

Some notes. They may not solves all your issues but they might help.

In epix_recipes_search(), you're using get_taxonomies() as if it were get_taxonomy() in your foreach loop.

You can replace all of this:

    'name' => $tax
$outputtype = 'objects'; // or objects

with this:

$taxonomieslist = get_taxonomy( $tax )

The $taxonomieslist is a bit of a misnomer since it only contains a single taxonomy object (I'd rename it accordingly, maybe $tax_object). Therefore, you can also drop all of this:

if ($taxonomieslist) {
    foreach ($taxonomieslist as $taxonomiesone ) {
        $output .= '  <h3>'. $taxonomiesone->labels->name. '</h3>'."\r\n";

And replace it with this:

$output .= '  <h3>'. $taxonomieslist->labels->name. '</h3>'."\r\n";

It also looks like you're missing a closing ">" on your </form> tag.

  • hey, No that did not fix them errors. however has helped clean up the code. many thanks Oct 2, 2014 at 8:04

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