Laravel 5.1, passing my ID - laravel

Question

I'm trying to pass an ID of a past and insert it into another database.
I got a page with shows posts like this
/posts/{id}
. From there on i want to add a comment section, so i got my form set up like this:
<form method="POST" action="/posts/{{ $post->id }}/comments">
(When i inspect the code, it inserts the right id and the "{{ $posts->id }}" spot.
inside my routes.php i got the folling route:
Route::post('/posts/{post}/comments', 'CommentsController#store');
and inside CommentsController.php i got the following
public function store(Post $post)
{
Comment::create([
'body' => request('body'),
'post_id' => $post->id
]);
return back();
}
When ever i try to add a comment i get this error:
SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'post_id'
cannot be null
When i change my code from CommentsController.php to this:
'post_id' => "2"
it works fine (but the comment will always be added at post with ID 2)
I can't seem to find out why my id wont go trough.
Anny help with this?

Answer 1

Try this
public function store(Request $request, Post $post)
{
$comment= new Comment;
$comment->body = $request->body;
$comment->post_id = $post->id;
$comment->save();
return back();
}
The route model binding allows you to convert the Post ID passed into the route into the actual post object in the controller method. It may even work smoother if you use a relationship between a post and a comment, like so:
public function store(Request $request, Post $post)
{
$post->comments->create([
'body' => $request->body
]);
return back();
}
Inside post model
public function comments()
{
return $this->hasMany('App\Comment','post_id');
}