title: Relation Fields prev: text: 'Rename Fields' link: '/advanced/rename' next: text: 'Allowed Fields' link: '/advanced/allowed'

Relation Fields

In this section, we're going to talk about how Purity can help you handle relation fields.

Filtering by Relation

First, you need to define the relation in your model:

use Illuminate\Database\Eloquent\Relations\HasMany;

class Post extends Model
{
use Filterable;

    public function tags(): HasMany
    {
        return $this->hasMany(Tag::class);
    }
}

Note that Purity read available fields from related models, you'll want to edit the $filterFields property in the related model. read more about $filterFields in allowed fields section.

class Tags extends Model
{
use Filterable;

    protected $filterFields = [
        'title',
    ];
}

Now you're all set to apply relation filtering! You can find some examples on the filter examples page.

Sorting by Relation

Purity supports sorting by the following relationship types:

• One to One
• One to Many
• Many to Many

Just like with filtering, you'll need to define the return type of the relations in your model:

use Illuminate\Database\Eloquent\Relations\HasMany;

class Post extends Model
{
use Sortable;

    public function tags(): HasMany
    {
        return $this->hasMany(Tag::class);
    }
}

Check out the sort examples page for some examples.