Custom Post Type Plugin not loading category template and loading 404 instead

Question

I have been looking around for the past few hours and I am starting to be kind of desperate...

I have created a plugin to add my custom post type "project" (making a new portfolio)...

In this plugin, I have the function file, and a template file single-project.php and also a template part folder with content-single-project.php within it. On that part, everything is working fine just as I want...

To be able to load the template file from the plugin folder, I did the following in the function file:

function get_custom_post_type_single_template($single_template) {
    global $post;

    if ($post->post_type == 'project') {
        $single_template = dirname( __FILE__ ) . '/templates/single-project.php';
    }
    return $single_template;
}

function get_custom_post_type_archive_template($archive_template) {
    global $post;

    if ($post->post_type == 'project') {
        $archive_template = dirname( __FILE__ ) . '/templates/archive-project.php';
    }
    return $archive_template;
}

function get_custom_post_type_category_template($category_template) {
    global $post;

    if ($post->post_type == 'project') {
        $category_template = dirname( __FILE__ ) . '/templates/category-project.php';
    }
    return $category_template;
}

add_filter( 'single_template', 'get_custom_post_type_single_template' );
add_filter( 'archive_template', 'get_custom_post_type_archive_template' );
add_filter( 'category_template', 'get_custom_post_type_category_template' );

Since it is working fine for the single template file, I don't see why I have a problem making it work for a category (or even archive) page... The category is not a custom taxonomy, it is the default (if I'm correct.. ) Category of Wordpress, same for Tags...

They are added in the project CPT while registering the new post type in the function file of the plugin, like so:

        'taxonomies' => array( 'post_tag', 'category' ),

They are "classic" right ?

Well... My primary navigation is displaying those categories (I have 3, Frontend, Design, Apps... ). When clicking on any of those links, redirecting to an URL like "root/category/post-name/", the 404 template is loaded, not the category template from the plugin folder, neither the one from the theme folder, neither archive... etc. Just the 404 template.

My permalinks are flush, I tried all the posts I have found online and nothing is changing, still not working...

I hope you guys will understand my english and will be able to help, Feel free to ask any question, Thank you for your time.

Answer 1

When clicking on any of those links, redirecting to an URL like "root/category/post-name/", the 404 template is loaded,

If you remove the category_template filter, are the links still 404?

For categories, your cpt post should appear in the list of posts in that category. So the url is root/category/.

When clicking on any of those cpt links, the single template should load and the url would be root/project/post-name/

Answer 2

Thanks to @shanebp, I have found the answer to the problem.

When registering a CPT, the taxonomies by default "category" and "tag" are the same as the one from the regular post. It means that the template needed to display the category related items is only the regular category.php. Therefore, my mistake was to thing of something like category-project.php (like it seems it was advertised on a few websites).

To have the categories from only a particular CPT, a custom taxonomy need to be created. Once the custom taxonomy is created taxonomy-yourtaxonomyslug.phpshould be working fine, or taxonomy-yourtaxonomyslug-thespecificterm.phpfor a specific term of the taxonomy.