Relations not loading as expected when using ->load() or ->loadMissing() when filtering within the relation method.

[wjstraver]

Hi all,

I've found a strange behaviour when I'm trying to load a relation which is filtered. To make my issue clear, I've got the following (simplified) Quiz model, which has multiple questions in an json column, an "active_question_key", and has a relation with quizAnswers:

class Quiz extends Model
{
    public $fillable = [
        'id',
        'questions',
        'active_question_key'
    ];
    
    public $casts = [
        'questions' => 'json'
    ];
    
    public answers(): HasMany
    {
        return $this->hasMany(QuizAnswer::class);
    }
    
    public activeQuestionAnswers(): HasMany
    {
        return $this->answers()->where('question_key', $this->active_question_key);
    }
}

The data of the $quiz->questions attribute looks in this example something like the following:

[
     [
        'key' => 'random-string',
        'question' => 'Lorem ipsum',
        'options' => [
            //...
        ]
    ],
    //...
]

As you can see in the model, the activeQuestionAnswers() relation, is based on the attribute active_question_key.
If I use this relation directly on the model, I get the result as expected:

dd($quiz->activeQuestionAnswers);
// --> Collection with x amount of answers with question_key same as active_question_key

However, if use ->load() or ->loadMissing(), the collection is empty

$quiz->load(['activeQuestionAnswers`]);
dd($quiz->activeQuestionAnswers);
// -> empty Collection

When I debug the relation as the following, I notice when using ->load() or ->loadMissing(), the relation method is not used on the selected model, but on a new and empty model class:

    public activeQuestionAnswers(): HasMany
    {
        dd($this->active_question_key, $this->id);
        return $this->answers()->where('question_key', $this->active_question_key);
    }

The dump are as follows:

$quiz->activeQuestionAnswers; // dumps "question_key" and "1"

$quiz->loadCount('activeQuestionAnswers'); // dumps "question_key" and "1"

$quiz->loadMissing('activeQuestionAnswers'); // dumps "null" and "null"

$quiz->load('activeQuestionAnswers'); // dumps "null" and "null"

My questions are:

• am I doing something wrong?
• is this a bug?
• is this a feature?
• should I not filter relations in this way?