5 star Rating System with AJAX Laravel 5.5

I am learning Laravel and I want to include in my project a 5 star Rating System with AJAX but the POST request is showing a 500 Internal Server Error. This is my controller:

public function favorite()
{
   var_dump('tesst');
    $this->validate($request, [
        'photo_id' => 'required|exists:photos,id',
        'rating' => 'required',
    ]);        
    $favorite= Favorites::create([
        'user_id'=>auth()->id(),
        'photo_id'=>request('photo_id'),
        'rating'=>request('rating')
    ]);
    return back();
}

and it doesnt enter the var_dump this is the AJAX request:

 $('.star').click(function(){
    //get the stars index from it id
    console.log('test');
    var rating = $(this).attr("id").split("-")[1],
        photo_id = $("#photo_id").val(), //store the photo id in variable
        star_container = $(this).parent(), //get the parent container of the stars
        result_div = $("#result"); //result div

    $.ajax({
        headers: {
        'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')
        } ,
        url: '/gallery/{id}/detail/'+rating,
        type: 'post',                     
        data: {rating:rating,photo_id:photo_id},
        beforeSend: function(){
            star_container.hide(); //hide the star container
            result_div.show().html("Loading..."); //show the result div and display a loadin message
        },
        success: function(data){
            result_div.html(data);
        }
    });
});

The html

<input type="hidden" value="" id="photo_id"> 
                    <div id="star-container">
                        <i class="fa fa-star fa-3x star" id="star-1"></i>
                        <i class="fa fa-star fa-3x star" id="star-2"></i>
                        <i class="fa fa-star fa-3x star" id="star-3"></i>
                        <i class="fa fa-star fa-3x star" id="star-4"></i>
                        <i class="fa fa-star fa-3x star" id="star-5"></i>
                    </div>  
                    <div id="result"> </div>    

And the route:

 //commenting on picture
Route::get('/gallery/{id}/detail', 'DetailController@index')->name('detail');
Route::post('gallery/{id}/detail','DetailController@store');
//favorites rating section
Route::post('/gallery/{id}/detail/{rating}', 'DetailController@favorite');
Route::get('/gallery/{id}/detail/{rating}', 'DetailController@show');

Can you please tell me what I'm doing wrong? I think it is a route problem.

via Chebli Mohamed