wp_dropdown_categories and custom taxonomy + custom post type

Question

I have created custom post type called "case study"(with slug case-study), with support of custom taxonomy which is called "theme".

What i am trying to achieve? Simple dropdown, with redirect to specific taxonomy term page on option select.

The code:

<form 
id="category-select" 
class="category-select"
action="<?php bloginfo('url'); ?>" method="get">

    <?php

    $args = array(
        'show_option_all'  => __( 'Choose theme', 'l-p' ),
        'hide_empty'       => 0,
        'echo'             => 0,
        'show_count'       => 0,
        'taxonomy'         => 'theme',
    );

    $select  = wp_dropdown_categories( $args );
    $replace = "<select$1 onchange='return this.form.submit()'>";
    $select  = preg_replace( '#<select([^>]*)>#', $replace, $select );

    echo $select;

    ?>

    <noscript><input type="submit" value="View" /></noscript>

</form>

Thing is, i'm getting dropdown with proper list of taxonomy terms, but when clicking on specifc option(from dropdown) it redirects me to weird pages/urls instead of actual taxonomy template page.

• I have tried saving direct links in wp settings.
• Taxonomy have proper template called taxonomy-theme.php
• The same dropdown works properly for default blog posts.
• CPT and taxonomy is created via CPT UI(i'm not really fond of it, but well, it was "required") - the support for taxonomy/cpt is checked in options.
• The slug for custom taxonomy is "theme".
• The slug for custom post type is "case-study".
• The taxonomy terms pages are present, it's just that dropdown redirects incorrectly.

Any help would be much appreciated.

Answer 1

You can get your code to work the expected way by adding the following three arguments to your $args array which you pass to wp_dropdown_categories():

• name — the select name as in <select name="<here>">, and you should set it to theme which is your custom taxonomy slug.

• value_field — the value of the <option>'s in that select dropdown, e.g. <option value="<here>">.

  And you should set the arg to slug so that when the form is submitted (or when a term is selected), the browser would go to https://example.com/?theme=term-slug-here and then WordPress redirects the browser to the correct term permalink if (and it's commonly) enabled.

• selected — the selected option which is a term in the custom theme taxonomy and because the form's destination is the term archive page, and that a term slug was specified (see the sample URL above), then set this arg to get_query_var( 'theme' ) to get the slug of the term being queried on the page.

So try with:

$args = array(
    'show_option_all' => __( 'Choose theme', 'l-p' ),
    'hide_empty'      => 0,
    'echo'            => 0,
    'show_count'      => 0,
    'taxonomy'        => 'theme',

    // Add these three args:
    'name'            => 'theme', // same as the "taxonomy" above
    'value_field'     => 'slug',  // use the term slug
    'selected'        => get_query_var( 'theme' ),
);