Attempt to read property "id" on null LARAVEL8

Question

I'm new to laravel and I'm learning it from laracast. Here is my problem, I'm creating a comment form and it's php code looks like this:

<section class="col-span-8 col-start-5 mt-10 space-y-6">
    <!-- Post form -->
    <form method="POST" action="/post/{{ $post->slug }}/comments" class="border border-gray-200 p-6 rounded-xl">
        @csrf
        <header class="flex items-center">
            <img src="https://i.pravatar.cc/100?id={{ auth()->id() }}" alt="" width="40" height="40" class="rounded-full">
            <h2 class="ml-3 ">Want to participate?</h2>
        </header>
        <div class="mt-6">
            <textarea class="w-full text-sm focus:outline-none focus:ring"
             name="body"  
             cols="30" rows="10"
              placeholder="Quick,think of something to say!" ></textarea>
        </div>
    
        <div>
            <button type="submit" class="bg-blue-500 text-white uppercase font-semi-bold text-xs py-2 px-10 rounded-2xl hover:bg-blue-600">Post</button>
        </div>
                        

this is the corresponding route:

Route::post('post/{post:slug}/comments',[PostCommentsController::class, 'store']);

                   

Controller:, and I suspect there could be something wrong here 'user_id'=> request()->user()->id , and I tried numerous ways for this approach like auth()->id, Auth::user()->id

<?php

namespace App\Http\Controllers;

use App\Models\Post;


class PostCommentsController extends Controller
{
    public function store(Post $post){

        
        request()->validate([
            'body'=>'required'
        ]);

        $post->comments()->create([
            'user_id'=> request()->user()->id,
            'body' => request('body')
        ]);

        return back();
    }
}

and this the migration table for comment

Schema::create('comments', function (Blueprint $table) {
            $table->id();
            $table->foreignId('post_id')->constrained()->cascadeOnDelete();
            $table->foreignId('user_id')->constrained()->cascadeOnDelete();
            $table->text('body');
            $table->timestamps();                       

migration table for post:

Schema::create('posts', function (Blueprint $table) {
    $table->id();
    $table->foreignId('user_id')->constrained()->cascadeOnDelete();
    $table->foreignId('category_id');
    $table->string('slug')->unique();
    $table->string('title');
    $table->text('excerpt');
    $table->text('body');
    $table->timestamps();
    $table->timestamp('published_at')->nullable();
});

If I click on post button I get the above error,tried my best to solve this problem but I couldn't. Can someone help me what's wrong with my code ?. My question may look naive as I'm new to stackoverflow community

Answer 1

use this code for controller

class PostCommentsController extends Controller
{
public function store(Post $post){

    
    request()->validate([
        'body'=>'required'
    ]);

    $post->comments()->create([
        'user_id'=> optional(auth()->user())->id,
        'body' => request('body')
    ]);

    return back();
}
}

user must logged in

Answer 2

first you must logged in

and in your route you must define your middleware if you are trying to get authenticated user's id like this

Route::post('post/{post:slug}/comments',[PostCommentsController::class, 'store'])->middleware('auth');

after that in your method/function inside controller use 'Request' class(not model class name) when you try to retrieve input from form

Laravel's 'Illuminate\Http\Request' class provides an object-oriented way to interact with the current HTTP request being handled by your application as well as retrieve the input, cookies, and files that were submitted with the request.

<?php

namespace App\Http\Controllers;

use App\Models\Post;
use Illuminate\Http\Request;  //don't forget this
    class PostCommentsController extends Controller
    {
    public function store(Request $request){
    
        
        request()->validate([
            'body'=>'required'
        ]);
    
        $post->comments()->create([
            'user_id'=> auth()->user()->id,
            'body' => request('body')
        ]);
    
        return back();
    }
    }