Non-permalink custom taxonomy not found

Question

I'm posting this as I found the problem, but it took me ages to find it with the mass of 'Refresh your permalinks' answers.

<?php
add_action( 'init', 'mytheme_create_post_type' );
function mytheme_create_post_type() {  // jobs custom post type
    // set up labels
    $job_labels = array(
        'name' => __( 'Jobs' ),
        'singular_name' => __( 'Job' ),
        'add_new' => __( 'Add New' ),
        'add_new_item' => __( 'Add New Job' ),
        'edit_item' => __( 'Edit Job' ),
        'new_item' => __( 'New Job' ),
        'all_items' => __( 'All Jobs' ),
        'view_item' => __( 'View Job' ),
        'search_items' => __( 'Search Jobs' ),
        'not_found' =>  __( 'No Jobs Found' ),
        'not_found_in_trash' => __( 'No Jobs found in Trash' ),
        'parent_item'       => __( 'Parent Job' ),
        'parent_item_colon' => __( 'Parent Job:' ),
        'menu_name' => __( 'Jobs' ),
    );
    register_post_type(
        'job',
        array(
            'labels' => $job_labels,
            'has_archive' => true,
            'public' => true,
            'hierarchical' => false,
            'supports' => array( 'title', 'editor', 'excerpt', 'custom-fields', 'thumbnail', 'page-attributes' ),
            'taxonomies' => array( 'post_tag', 'job_category' ),
            'exclude_from_search' => true,
            'capability_type' => 'post'
        )
    );

    register_taxonomy_for_object_type( 'job_category', 'job' );
}

add_action( 'init', 'mytheme_create_taxonomies', 5 );
function mytheme_create_taxonomies() {
    // job taxonomy
    $job_labels = array(
        'name'              => _x( 'Job Categories', 'taxonomy general name' ),
        'singular_name'     => _x( 'Job Category', 'taxonomy singular name' ),
        'search_items'      => __( 'Search Job Categories' ),
        'all_items'         => __( 'All Job Categories' ),
        'parent_item'       => __( 'Parent Job Category' ),
        'parent_item_colon' => __( 'Parent Job Category:' ),
        'edit_item'         => __( 'Edit Job Category' ),
        'update_item'       => __( 'Update Job Category' ),
        'add_new_item'      => __( 'Add New Job Category' ),
        'new_item_name'     => __( 'New Job Category' ),
        'menu_name'         => __( 'Job Categories' ),
    );
    register_taxonomy(
        'job_category',
        'job',
        array(
            'hierarchical' => false,
            'labels' => $job_labels,
            'rewrite' => false,
            'show_admin_column' => true
        )
    );
}

Given the problems with permalinks I'd turned everything off. I'd set Settings > Permalinks to default and set rewrite => false for both the post type and the taxonomy.

However after creating a Job with a category of HR going to http://www.example.com/?job_category=hr gave me a 'Sorry no results found' i.e. not a 404 but no results for that category.

Answer 1

The problem was 'exclude_from_search' => true in the register_post_type options.

Given that setting 'public' => true defaults to exluding from search by default I assumed that this was the correct setting.

However this is in the WordPress codex for register_post_type exclude_from_search:

Note: If you want to show the posts's list that are associated to taxonomy's terms, you must set exclude_from_search to false (ie : for call site_domaine/?taxonomy_slug=term_slug or site_domaine/taxonomy_slug/term_slug). If you set to true, on the taxonomy page (ex: taxonomy.php) WordPress will not find your posts and/or pagination will make 404 error...