如何限制 whereHas 只匹配 where 条件？

Question

I am using Laravel 6.0 and PostgreSQL on Homestead.

This query is returning services which has at least one post with is_assistant = true :

Service::with('posts')
    ->whereHas('posts', function ($q) {
        $q->where('is_assistant', true);
    })
    ->get();

Models:

class Service extends Model
{
    public function posts()
    {
        return $this->belongsToMany('App\Post');
    }
}

class Post extends Model
{

    protected $casts = [
        'is_assistant' => 'boolean',
    ];

}

How to write an Eloquent query that get services which has ONLY posts with is_assistant = true ?

Answer 1

Can use the whereDoesntHave method:

Service::with('posts')
    ->whereDoesntHave('posts', function ($q) {
        $q->where('is_assistant', false);
    })
    ->get();