使用JSON时如何传递参数？

Question

I can't get my images to save because of an Unpermitted parameter: image error . Using dropzone.js , I have to upload the form by JSON if I want to have to ability to drag and drop images on the file field. I'm trying to allow only one image to be uploaded to the model. Here is my code:

items.rb

class Item < ActiveRecord::Base
.....
validates_inclusion_of :found, in: [true, false]

has_attached_file :image, :styles => { :medium => "350x350>", :thumb => "100x100>" }
validates_attachment :image,
        content_type: { content_type: [ "image/jpg", "image/jpeg", "image/png" ] },
        size: { in: 0..1.megabytes },
        matches: [/png\Z/, /jpe?g\Z/]

end

items.coffee

  $('#new_item').dropzone
    acceptedFiles: '.jpeg, .jpg, .png'
    maxFilesize: 1
    maxFiles: 100
    addRemoveLinks: true
    paramName: 'item[image]'
    clickable: '#image-preview'
    headers: "X-CSRF-Token" : $('meta[name="csrf-token"]').attr('content')
    previewsContainer: '#image-preview'
    thumbnailWidth: 300
    thumbnailHeight: 300
    autoProcessQueue: false
    uploadMultiple: true
    parallelUploads: 100
    init: ->
      myDropzone = this
      @element.querySelector('#item-submit').addEventListener 'click', (e) ->
        e.preventDefault()
        e.stopPropagation()
        if myDropzone.getQueuedFiles().length > 0
          myDropzone.processQueue()
        else
          $("#new_item").submit();
        return
      @on 'sendingmultiple', ->
        return
      @on 'successmultiple', (files, response) ->
        return
      @on 'errormultiple', (files, response) ->
        return
      return

items_controller.rb

class ItemsController < ApplicationController

      def create
        @item = current_user.items.build(item_params)
        if @item.save
          if request.xhr?
            render json: {
              location: url_for(controller: 'items', action: 'continue', id: @item),
              flash: {notice: "Successfully posted item!"}
            }
          else
            redirect_to(controller: 'items', action: 'continue', id: @item)
          end
        else
          render json: @item.errors, status: :unprocessable_entity
        end
      end

  private

  def item_params
    params.require(:item).permit(:name, :description, :image)
  end

  def find_item
    @item = Item.find(params[:id])
  end

end

routes.rb

  resources :items do
    collection do
      get 'lost', to: 'items#index_lost'
      get 'found', to: 'items#index_found'
    end
    get '/post/continue', to: 'items#continue', on: :member
  end

items/_form.haml

= form_for @item, validate: true, html: {multipart: true} do |f|
    = f.label :name, class: 'col-lg-2 control-label'
        = f.text_field :name
    %main#image-preview
        .fallback
            = f.file_field :image, multiple: false
    .submit-section
        .col-lg-12.col-md-12
            = f.submit 'Done', id: 'item-submit'

(Note: validate: true is from the client_side_validation gem )

So the error I get after submitting the form is:

Started POST "/items" for 127.0.0.1 at ............
Processing by ItemsController#create as JSON
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"SAIGiG9SjnuTKfsmxszBFfK+lZVojS2UmDi9hTeC8wI6B2fGZ+sZM9te3lIFkFsT30SdFWjyXZMZI7zXAlAMGA==", "item"=>{name"=>"Post Item", image"=>{"0"=>#<ActionDispatch::Http::UploadedFile:0x007f3d248b5a98 @tempfile=#<Tempfile:/tmp/RackMultipart20151002-2427-1cvzgsi.jpg>, @original_filename="haribo.jpg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name=\"item[image][0]\"; filename=\"haribo.jpg\"\r\nContent-Type: image/jpeg\r\n">}}, "null"=>"", "commit"=>"Done"}
Unpermitted parameter: image
..........
    Completed 200 OK in 230ms (Views: 0.3ms | Searchkick: 31.1ms | ActiveRecord: 14.3ms)

Now after all of this it still saves but it just causes image not to because I also want to allow the user to submit the form without an image. How do I fix this?

Answer 1

You submitted params include image attribute as Hash

image"=>{"0"=>#<ActionDispatch::Http::UploadedFile:0x007f3d248b5a98 ...

It should be like :

"image"=>#<ActionDispatch::Http::UploadedFile:0x007f3d248b5a98 @tempfile= ...