Test-Eloquent-Relationships/app/Http/Controllers/ProjectController.php

<?php

namespace App\Http\Controllers;

use App\Models\Project;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Auth;

class ProjectController extends Controller
{
    public function store(Request $request)
    {
        // TASK: Add one sentence to save the project to the logged-in user
        //   by $request->project_id and with $request->start_date parameter

        /** @var \App\Models\User $user */
        Auth::user()->projects()->attach($request->project_id, ['start_date' => $request->start_date]);

        return 'Success';
    }
}