jquery file Upload rails “Error Empty file upload

Question

I have such view (form partial):

= javascript_include_tag 'car_photos'
= stylesheet_link_tag('jquery.fileupload-ui')
= form_for @car do |f|
  - if @car.errors.any?
    #error_explanation
      %h2= "Ошибки в полях: #{pluralize(@car.errors.count, "error")}"
      %ul
        - @car.errors.full_messages.each do |msg|
          %li= msg
  .tab#car-data{style: "height: 1290px;"}
    .field
      = f.label :manufacturer_id, "Марка"
      = f.select(:manufacturer_id, options_from_collection_for_select(VehicleManufacturer.all, :id, :name, @car.manufacturer_id), {}, :prompt => "Выберите марку", required: true, id: "manufacturer-select")
    .field
      = f.label :model_id, "Модель"
      #models-area
        = render :partial => 'models', :object => @models
    .actions
      = link_to 'Перейти к загрузке фотографий', "", id: "go-and-load-photos", remote: true
  .tab#car-photo{style: "height: 1290px;"}
    .actions
      = link_to 'Назад к описанию', "", id: "go-and-load-car-data", remote: true
  .actions
    = f.submit 'Добавить', id: "submit-car"
.car-photo
  = form_for CarPhoto.new, :html => { :multipart => true, :id => "fileupload", remote: true  } do |f|
    .row.fileupload-buttonbar
      %span.fileinput-button
        %span Добавить файлы
        = f.file_field :car_photo, multiple: true
        = tag(:input, :type => "hidden", :name => request_forgery_protection_token.to_s, :value => form_authenticity_token)
      %button.btn.btn-primary.start{type: "submit", remote: true}
        %span Загрузить
      %button.btn.btn-warning.cancel{type: "reset", remote: true}
        %span Отменить загрузку
      %button.btn.btn-danger.delete{type: "button", remote: true}
        %span Удалить
      %input.toggle{type: "checkbox"}/
    %table.table.table-striped
      %tbody.files{"data-target" => "#modal-gallery", "data-toggle" => "modal-gallery"}
:javascript
  var fileUploadErrors = {
      maxFileSize: 'Размер файла слишком велик',
      minFileSize: 'Размер файла слишком мал',
      acceptFileTypes: 'Расширение файла не поддерживается',
      maxNumberOfFiles: 'Превышен лимит файлов',
      uploadedBytes: 'Uploaded bytes exceed file size',
      emptyResult: 'Файл не был загружен'
  };
/ The template to display files available for upload
%script#template-upload{type: "text/x-tmpl"}
  {% for (var i=0, file; file=o.files[i]; i++) { %}
  <tr class="template-upload fade">
  <td class="preview"><span class="fade"></span></td>
  <td class="name"><span>{%=file.name%}</span></td>
  <td class="size"><span>{%=o.formatFileSize(file.size)%}</span></td>
  {% if (file.error) { %}
  <td class="error" colspan="2"><span class="label label-important">{%=locale.fileupload.error%}</span> {%=locale.fileupload.errors[file.error] || file.error%}</td>
  {% } else if (o.files.valid && !i) { %}
  <td>
  </td>
  <td class="start">{% if (!o.options.autoUpload) { %}
  <button class="btn btn-primary">
  <span>Загрузить</span>
  </button>
  {% } %}</td>
  {% } else { %}
  <td colspan="2"></td>
  {% } %}
  <td class="cancel">{% if (!i) { %}
  <button class="btn btn-warning">
  <span>Отменить загрузку</span>
  </button>
  {% } %}</td>
  </tr>
  {% } %}
/ The template to display files available for download
%script#template-download{type: "text/x-tmpl"}
  {% for (var i=0, file; file=o.files[i]; i++) { %}
  <tr class="template-download fade">
  {% if (file.error) { %}
  <td></td>
  <td class="name"><span>{%=file.name%}</span></td>
  <td class="size"><span>{%=o.formatFileSize(file.size)%}</span></td>
  <td class="error" colspan="2"><span class="label label-important">{%=locale.fileupload.error%}</span> {%=locale.fileupload.errors[file.error] || file.error%}</td>
  {% } else { %}
  <td class="preview">{% if (file.thumbnail_url) { %}
  <a href="{%=file.url%}" title="{%=file.name%}" rel="gallery" download="{%=file.name%}"><img src="{%=file.thumbnail_url%}"></a>
  {% } %}</td>
  <td class="name">
  <a href="{%=file.url%}" title="{%=file.name%}" rel="{%=file.thumbnail_url&&'gallery'%}" download="{%=file.name%}">{%=file.name%}</a>
  </td>
  <td class="size"><span>{%=o.formatFileSize(file.size)%}</span></td>
  <td colspan="2"></td>
  {% } %}
  <td class="delete">
  <button class="btn btn-danger" data-type="{%=file.delete_type%}" data-url="{%=file.delete_url%}">
  <span>Удалить</span>
  </button>
  <input type="checkbox" name="delete" value="1">
  </td>
  </tr>
  {% } %}
%script{charset: "utf-8", type: "text/javascript"}
  $(function () {
  \// Initialize the jQuery File Upload widget:
  $('#fileupload').fileupload();
  \//
  \// Load existing files:
  $.getJSON($('#fileupload').prop('action'), function (files) {
  var fu = $('#fileupload').data('fileupload'),
  template;
  fu._adjustMaxNumberOfFiles(-files.length);
  console.log(files);
  template = fu._renderDownload(files)
  \.appendTo($('#fileupload .files'));
  \// Force reflow:
  fu._reflow = fu._transition && template.length &&
  template[0].offsetWidth;
  template.addClass('in');
  $('#loading').remove();
  });

  });

As you can see i try to upload multiple images, controller is such:

class CarPhotosController < ApplicationController
  before_action :set_car_photo, only: [:show, :edit, :update, :destroy]

  def new
    @car_photo = CarPhoto.new
  end

  def create 
    #binding.pry
    @car_photo = CarPhoto.new(car_photo: car_photo_params[:car_photo].first) 
    #binding.pry
    #@car_photo.user_id = current_user.id
    respond_to do |format| 
      if @car_photo.save #&& user_signed_in?
        format.html { redirect_to @car_photo, notice: 'Photo was successfully created.' } 
        format.json { data = {id: @car_photo.id, thumb: view_context.image_tag(@car_photo.car_photo.url(:thumb))} 
        render json: data, status: :created, location: @car_photo } 
      else 
        format.html { render action: "new" } 
        format.json { render json: @car_photo.errors, status: :unprocessable_entity } 
      end 
    end 
  end

  private
  # Use callbacks to share common setup or constraints between actions.
  def set_car_photo
    @car_photo = CarPhoto.find(params[:id])
  end

  # Never trust parameters from the scary internet, only allow the white list through.
  def car_photo_params
    params.require(:car_photo).permit(:car_photo, {:car_photo => []})
  end
end

and when i submit some image in chrome log i see, that server return such json:

{"id":31,"thumb":"\u003Cimg alt=\"1\" src=\"/system/car_photos/car_photos/000/000/031/thumb/1.jpg?1394785415\" /\u003E"}

and in db i see that it is saved, but why in view i get :

Error Empty file upload result  

what i do wrong? and how to solve it?

Answer 1

jquery-file-upload library requires JSON response in specific format: https://github.com/blueimp/jQuery-File-Upload/wiki/JSON-Response

This might be the problem.

By the way, please don't send response the way you do, I mean, don't call view methods in your controller. Either send just the url in response and add <img> tag in fileUpload callback or render it in view (using for example jbuilder gem)