get an error that says, "No query results for model [App/dummy]"?

What I am trying to do is be able to post comments from a form to the post. I know the names for my models are bad. It should have been called post instead of dummy. I got this error when I called my new controller I made for the comments table. Also, I created a new function in the dummy model so my code can be more clean and organized. I was able to post comments before I made the new function in the dummy model and before I called a different controller. Here are the files that I think the errors is in:

Here is the route:

Route::post('post/{post}/comments', 'commentController@store');

Here is the dummy model which should have been called post and has the new function i created for it to make the code shorter in the commentController file:

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class dummy extends Model
{
    protected $guarded = [];

    public function comments(){
      return $this->hasMany(Comments::class, 'post_id');
    }

    public function addComment($body){
      $this->comments()->create(compact('body')); 
    }
}

Lastly here is the commentController file:

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use Illuminate\Support\Facades\DB; //this one is for sql builders
use App\Dummy;
use App\Comments;
use Illuminate\Http\RedirectResponse;
use DateTime; //to create a new date object yo need to include this namespace



class commentController extends Controller
{
  public function store(Dummy $post){
    $date = new DateTime();
    $timestamp = $date->getTimestamp();
    $id = $post->id;

    $post->addComment(request('body'));

    return view('post', compact('post', 'timestamp', 'id'));
  }
}

via Lami