Запрос laravel Ajax не обрабатывает php

Пожалуйста, помогите мне, я очень вам благодарен ............

Это мой код, он работает нормально, если я удалил php-код из контроллера, он отлично работает, что я делаю, чтобы решить проблему с запросом ajax.

{{csrf_field ()}}

    <div class = "form-group">
        <label for = "exampleInputEmail1">Watch Name</label>
       <div class = "input-group mb-2 mr-sm-2">
        <div class = "input-group-prepend">
          <div class = "input-group-text">
              <i class = "fas fa-pen-fancy fa"></i></div>
        </div>

        <input type = "text" class = "form-control form-control-lg" 
        name = "watch_name" placeholder = "Enter Watch Name" id = "name">
      </div>
    </div>


    <div class = "form-group">
        <label for = "exampleInputEmail1">Watch Price</label>
    <div class = "input-group mb-2 mr-sm-2">

        <div class = "input-group-prepend">
          <div class = "input-group-text">
            <i class = "fa fas fa-hand-holding-usd"></i></div>
        </div>

        <input type = "number" name = "watch_price" class = "form-control" 
        id = "inlineFormInputGroupUsername2" placeholder = "Enter watch Price">
      </div>
    </div>


    <div class = "form-group">
        <label for = "exampleInputEmail1">Enter Quantity Available</label>
    <div class = "input-group mb-2 mr-sm-2">

        <div class = "input-group-prepend">
          <div class = "input-group-text">
            <i class = "fa fas fa-battery-three-quarters"></i></div>
        </div>

        <input type = "number" name = "watch_quantity" class = "form-control" id = "inlineFormInputGroupUsername2" placeholder = "Enter watches quantity">
      </div>
    </div>



      <div class = "form-group">
          <label for = "exampleInputEmail1">Watch Image 1</label>
       <div class = "input-group mb-2 mr-sm-2">

          <div class = "input-group-prepend">
            <div class = "input-group-text">
              <i class = "fa fas fa-images"></i></div>
          </div>

      <input type = "file" class = "form-control" 
      id = "img1" name = "image1" placeholder = "Username">
        </div>
      </div>

      <div class = "form-group">
          <label for = "exampleInputEmail1">Watch Image 2</label>
       <div class = "input-group mb-2 mr-sm-2">

          <div class = "input-group-prepend">
            <div class = "input-group-text"><i class = "fa fas fa-images"></i></div>
          </div>

      <input type = "file" class = "form-control" 
      id = "inlineFormInputGroupUsername2" name = "image2" placeholder = "Username">
        </div>
      </div>

      <div class = "form-group">
          <label for = "exampleInputEmail1">Watch Image 3</label>
       <div class = "input-group mb-2 mr-sm-2">

          <div class = "input-group-prepend">
            <div class = "input-group-text"><i class = "fa fas fa-images"></i></div>
          </div>

      <input type = "file" class = "form-control" 
      id = "inlineFormInputGroupUsername2" name = "image3" placeholder = "Username">
        </div>
      </div>

      <div class = "form-group">
          <label for = "exampleFormControlSelect2">Watch size Availble</label>
          <select multiple class = "form-control"
           id = "exampleFormControlSelect2" 
          name = "watch_size">
            <option value = "small">small</option>
            <option value = "medium">Medium</option>
            <option value = "large">Large</option>
            <option selected value = "small&medium&large">all</option>

          </select>
        </div>

        <div class = "form-group">
            <label for = "exampleFormControlSelect2">Watch color</label>
            <select multiple class = "form-control"
             id = "exampleFormControlSelect2" 
            name = "watch_color">
              <option value = "red">red</option>
              <option value = "blue">blue</option>
              <option value = "black" selected>black</option>
              <option value = "golden">golden</option>
              <option value = "gray">gray</option>
              <option value = "ofwhite">ofwhite</option>
              <option value = "red.blue.black.golden.gray.ofwhite">all</option>

              <option selected value = "small&medium&large">all</option>

            </select>
          </div>




      <div class = "form-group">
          <label for = "exampleFormControlTextarea1">Discription</label>
          <textarea class = "form-control" 
          id = "exampleFormControlTextarea1" rows = "5" 
          name = "discription" placeholder = "Enter discription if Any !"></textarea>
        </div>

    <button type = "submit" class = "btn btn-primary">Submit</button>

**

*********** Это мой код AJax: ************************

     // 

      $(document).ready(function() {

        insertdata();

      function insertdata(){

      $('#form_output').hide();

                $("#watch-form").submit(function(e) {
                    e.preventDefault();

               var formData = new FormData(this);


                    $.ajax( {

                     url:"{{ route('add_watch.postdata') }}",
                     method: "POST",
                     data:formData,
                     dataType: 'json',
                     async: true, 


                      success: function(data) { 

             if (data.error.length > 0)
            {
              $('#form_output').show();
              $('.alert ul li').remove();

              var error_html = '';
              for(var count = 0; count < data.error.length; count++)
            {

         error_html += data.error[count];
         console.info(data.error[count]);
         $('.alert ul').append('<li>'+data.error[count]+'</li>');


          }//for loop end

           // $('#form_ul').html(error_html);

            }//if condition 
            else{

             $('#form_output').show();
                console.info(data.success);
                $('.alert ul').append('<h2>'+data.success+'</h2>');

                $("#watch-form")[0].reset();


            }//else end here                               

                        },contentType: false,
                     processData: false
                    });
                });




    }//insertData end function
  });//end document

/ ****************** ******************************* ******* //

    $validation = Validator::make($request->all(), [
        'watch_name' => 'required',
        'watch_price'  => 'required',
        'watch_quantity'  => 'required',
        'image1'  => 'required|image|mimes:jpeg,png,jpg,gif,svg|max:2048',
        'image2'  =>  'required|image|mimes:jpeg,png,jpg,gif,svg|max:2048',
        'image3'  =>  'required|image|mimes:jpeg,png,jpg,gif,svg|max:2048',
        'watch_size'  => 'required',
        'watch_color'  => 'required',
        'discription'  => 'required',

    ]);

    $error_array = array();
    $success_output = "";
    if ($validation->fails())
    {
        foreach($validation->messages()->getMessages() as $field_name => $messages)
        {
            $error_array[] = $messages;
        }
    }else{  


   $userWatches = new userWatches;
   $userWatches->watch_name=$request->input('watch_name');
   $userWatches->watch_price=$request->input('watch_price');
   $userWatches->image1=$request->input('image1');
   $userWatches->image2=$request->input('image2');
   $userWatches->image3=$request->input('image3');
   $userWatches->watch_discription=$request->input('watch_discription');
   $post->save();           

   $success_output = 'Your data is success fully updated';

    }

    $output = array(
        'error'     =>  $error_array,
        'success'   =>  $success_output            
    );
    echo json_encode($output);
}