Get all records of relationship when parent doesn't exist

问题

I have two models.

Resource:

public function account()
{
    return $this->belongsTo('App\Account');
}

Account:

public function resources()
{
    return $this->hasMany('App\Resource');
}

I want to receive all resources of an account knowing user_id from account Model.

Account::where('user_id', Auth::id())->first()->resources()->get();

This works only when account exists. It throws error otherwise: Call to a member function resources() on null.

What's the smart way to get all resources in Eloquent? The best would be to use only one query statement in the background, because I know above example is using two queries.

回答1:

You can leverage the whereHas() eloquent method to select all Resources attached to account who belongs to a specific user_id. Try this:

 $resources =  Resource::whereHas('account', function ($query)
        {
            $query->where('user_id', Auth::id());
        })->get();

Doc: https://laravel.com/docs/8.x/eloquent-relationships#querying-relationship-existence

来源：https://stackoverflow.com/questions/65219020/get-all-records-of-relationship-when-parent-doesnt-exist