Why the related Answer model doesn't get project_id? - laravel

Question

I have the next models:
Project <(Many to Many)> Experiment (One to Many)> Question (One to Many)> Answer
When I try Project::with('experiments.questions.answers')->find(1)
as result, I get answers not only from project with id: 1, but from others too.
Structure Answer model:
<?php
use App\Models\Answer;
use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;
class CreateAnswersTable extends Migration
{
/**
* Run the migrations.
*
* #return void
*/
public function up()
{
Schema::create('answers', function (Blueprint $table) {
$table->increments('id');
$table->string('answer')->nullable();
$table->integer('confidence_score')->unsigned()->default(0);
$table->integer('state')->unsigned()->default(Answer::READY);
$table->integer('element_id')->unsigned();
$table->integer('question_id')->unsigned();
$table->integer('project_id')->unsigned();
$table->timestamps();
$table->foreign('question_id')->references('id')->on('questions')->onDelete('cascade');
$table->foreign('project_id')->references('id')->on('projects')->onDelete('cascade');
});
}
/**
* Reverse the migrations.
*
* #return void
*/
public function down()
{
Schema::table('answers', function ($table) {
$table->dropForeign(['question_id']);
$table->dropForeign(['project_id']);
});
Schema::drop('answers');
}
}
If I add the next condition, it is work:
Project::with(['experiments.questions.answers' => function($query) {$query->where('project_id', 1);}])->find(1)
But how can I remove it from the code and to make it global?

Answer 1

I can't figure out why this selection touch other projects, however, if you want to create a handy shortcut to fetch project with relations - create a method in a Model or your Repository:
public function findWithExperiments($id) {
$project = Project::find($id);
$project->load(['experiments.questions.answers' => function ($query) use ($id) {
$query->where('project_id', $id);
}]);
return $project;
}

Answer 2

Try this code
Project::with('experiments.questions.answers')->find([1])