Laravel Relationship Gotcha

Laravel is nice. It lets you define relationships painlessly.

// app/MultipleChoiceQuestion.php
class MultipleChoiceQuestion extends Model
{
    public function answers()
    {
        return $this->hasMany(\App\Answer::class);
    }
}

We can even make relationships in the other direction.

// app/Answer.php
class Answer extends Model
{
    public function question()
    {
        return $this->belongsTo(\App\MultipleChoiceQuestion::class);
    }
}

If we know we're often going to query for the answers to our questions when we query for the questions, it makes sense to eager load them by default.

// app/MultipleChoiceQuestion.php
class MultipleChoiceQuestion extends Model
{
    protected $with = ['answers'];

    public function answers()
    {
        return $this->hasMany(\App\Answer::class);
    }
}

But what happens when we eager load the question on the answer as well?

// app/Answer.php
class Answer extends Model
{
    protected $with = ['question'];

    public function question()
    {
        return $this->belongsTo(\App\MultipleChoiceQuestion::class);
    }
}

Chaos. When you query the question you query for its answers as well which in turn queries for the question they belongs to and...

Your relationships must terminate somewhere.