Laravel / Eloquent-查询-按关系选择

Question

Models

class Model1 extends Eloquent {
    public function model2() {
        return $this->hasOne('Model2');
    }
}

class Model2 extends Eloquent {
    public function model1() {
        return $this->belongsTo('Model1');
    }
}

Query I want

I want to get all instances from Model1 which do not have a Model2 . In other words, there isn't any reference to that Model1 id in Model2 table column model1_id .

This could be achieved with a foreach loop, iterating all the Model1 and checking if the model2 atributte is null . But I want to do it with Eloquent queries.

Answer 1

You might try something like

Model1::has('model2', '=', 0)->get();

See: Laravel Docs - Eloquent - Querying Relations

Update:

Model1::doesntHave('model2')->get();

Answer 2

This might be it:

$ids = Model2::where('model1_id', null)->lists('id');
$result = Model1::whereIn('id', $ids)->get();

edit:
I need to learn to read better :) I see that this is not it.

edit2:
This might be it. I havent tested it, but if there is an error then it should be easy to fix it! (With the help of lagbox on IRC channel #laravel)

edit3:
Okey, so after discussing it on #laravel with lagbox there is a even better way... see his answer