Relationships

In WordPress, post types can have many taxonomies, and taxonomies can belong to many post types.

In Fresa, these two relationship types are defined as HasTaxonomy and BelongsToPost.

HasTaxonomy Relationships

In order to allow a custom Post Model instance to interact with a Taxonomy, add a method to your model:

class Event extends PostModel
{
    public function categories()
    {
        return $this->hasTaxonomy(EventCategory::class);
    }
}

This allows you to attach taxonomy terms to specific post models, and vice versa:

$category = EventCategory::find(123);
$event->categories()->save($category);

Taxonomy terms will be available as a dynamic property on your post model object using the same name as the method you defined:

foreach ($event->categories as $category) {
    echo $category->name;
}

BelongsToPost Relationships

When working with a taxonomy, you may find it convenient to be able to filter posts of a given taxonomy term.

Add a method to your taxonomy to create that relationship:

class EventCategory extends Taxonomy
{
    public function events() {
        return $this->belongsToPost(Event::class);
    }
}

Then you can use the name of the method you created to attach a given category to a post model:

$category = EventCategory::create([
    'name' => 'Fiesta!',
]);

$event = Event::create([
    'title' => 'Strawberry Party',
]);

$category->events()->save($event);

You can use the name of the method as a dynamic property get a collection of related models:

$category->events->first()->title; // 'Strawberry Party'

WordPress Requirements

When creating relationships and saving related models, both PostModel and Taxonomy instances need to have been registered with WordPress as valid custom types. This can be done with the register method or by using the traditional registration method.