Different templates for parent and children Taxonomy

Question

I have new custom Taxonomy for cars list spec. I would like to know what is the best way to create a different template for parent(main) and second layer and the third layer children taxonomies.

I can not use this way taxonomy-{taxonomy}-{slug}.php, Because I have a lot of category and subcategory names.

First there is the Brands page (main tax):

BMW
Benz
Volvo
And..

If I choose BMW for example. there is the Series page (second layer):

Series 1
Series 2
Series 3
And...

And if, for example, I choose series 3, I will enter the page of Generations of this series (third layer):

E21
E21 facelift
E30
And..

And if I choose E21 for example:

I enter the specifications page of this car (my new post-type).

Url: mysite{dot}com/cars/bmw/3-series/e21

I want each of the layers of the main category, the second layer, and the third layer to have a separate template.

Update: In this answer we can seperate children and parent. How I can do this for the second layer and the third layer children?

Answer 1

The {$type}_template_hierarchy filter can be used to add templates to the list of files to check for each request:

Filters the list of template filenames that are searched for when retrieving a template to use.

With this filter, you can do something like below: add to theme's functions.php or an mu-plugin (untested):

add_filter( 'taxonomy_template_hierarchy', static function ( $templates ) {
    $term = get_queried_object();

    if ( 'car-brand' !== $term->taxonomy ) {
        return $templates;
    }

    $ancestors = get_ancestors( $term->term_id, 'car-brand', 'taxonomy' );

    $new_template = sprintf( 'car-brand-ancestors-%d.php', count( $ancestors ) );

    return array( $new_template ) + $templates;
} );

With this approach, templates would apply like so:

Top-level Term: car-brand-ancestors-0.php
└─ Child Term: car-brand-ancestors-1.php
   └─ Grandchild Term: car-brand-ancestors-2.php

I use Query Monitor to check the template hierarchy, and I would recommend doing so here, as you'll probably want to adjust to prioritize more specific templates first.

Answer 2

Solution: This is worked fine:

In may taxonomy-MyTaxName.php file:

<?php
$term = get_term_by('slug', get_query_var('term'), 'MyTaxName');
$ancestors = get_ancestors( $term->term_id, 'MyTaxName', 'taxonomy' );
if (count( $ancestors ) == 0) {
  get_template_part('MyTaxName', '1');
}
if (count( $ancestors ) == 1) {
  get_template_part('MyTaxName', '2');
}
if (count( $ancestors ) == 2) {
  get_template_part('MyTaxName', '3');
}
?>

And I created 3 files:

1. MyTaxName-1.php

2. MyTaxName-1.php

3. MyTaxName-1.php