Rails表单字段数组名称和参数

Question

I have this field inside the following form: <%= form.file_field :image, multiple: true, name: 'attachment[image][]', id: "uploads" %>

<%= form_for @attachment, url: create_attachment_path(@attachment), :html => {:id => "form", :multipart => true }, method: :post do |form| %>
      <% if @attachment.errors.any? %>
        <div class="centerList">
          <div id="error_explanation">
            <h2><%= pluralize(item.errors.count, "error") %> <%= t 'store_item_edit_4' %></h2>
            <% @attachment.errors.full_messages.each do |message| %>
              <li><%= message %></li>
            <% end %>
          </div>
        </div>
      <% end %>
      <div class="form-group">
        <div class="text-center">
          <label class="btn btn-primary"><%= t 'store_item_edit_5' %><span style="display:none;">
            <%= hidden_field_tag :item_id, params[:item_id], value: @item.id  %>

         <%= form.file_field :image, multiple: true, name: 'attachment[image][]', id: "uploads" %></span></label>
          <%= form.submit '', :style => "display: none;" %>
    <% end %>

I'm trying to add multiple images to the db with this action:

 def create
    @attachment = Attachment.new(attachment_params)

    respond_to do |format|
      if @attachment.save
        format.html { redirect_back fallback_location: root_path, notice: 'Image was successfully uploaded.' }
      else
        format.html { render :new }
        format.json { render json: @attachment.errors, status: :unprocessable_entity }
      end
    end
  end

these are the params I have inside the controller:

def attachment_params
    params.require(:attachment).permit(:item_id, :account_id, :image)
end

But I'm getting `Unpermitted parameter: :image' inside the console, the db row gets created but with null values.

Started POST "/attachments/create" for 127.0.0.1 at 2018-03-15 11:50:26 +0200
Processing by AttachmentsController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"s0S6EwMgF9ac6djr028OfPBCXdKTM/NTjZFHdxi4Ot9MlUQZjHa5+0PNIu0Fg54b36SdWVzUE0g7fb3BJtF2gA==", "item_id"=>"2", "attachment"=>{"image"=>[#<ActionDispatch::Http::UploadedFile:0x007f82cf881090 @tempfile=#<Tempfile:/var/folders/hq/pr4rt14n7s31v3f6292wtjm00000gn/T/RackMultipart20180315-1190-mrrhdh.jpg>, @original_filename="image5.jpg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name=\"attachment[image][]\"; filename=\"image5.jpg\"\r\nContent-Type: image/jpeg\r\n">, #<ActionDispatch::Http::UploadedFile:0x007f82cf880f78 @tempfile=#<Tempfile:/var/folders/hq/pr4rt14n7s31v3f6292wtjm00000gn/T/RackMultipart20180315-1190-18zuptn.jpg>, @original_filename="image6.jpg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name=\"attachment[image][]\"; filename=\"image6.jpg\"\r\nContent-Type: image/jpeg\r\n">, #<ActionDispatch::Http::UploadedFile:0x007f82cf880ed8 @tempfile=#<Tempfile:/var/folders/hq/pr4rt14n7s31v3f6292wtjm00000gn/T/RackMultipart20180315-1190-1iuevmq.jpg>, @original_filename="image7.jpg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name=\"attachment[image][]\"; filename=\"image7.jpg\"\r\nContent-Type: image/jpeg\r\n">, #<ActionDispatch::Http::UploadedFile:0x007f82cf880e88 @tempfile=#<Tempfile:/var/folders/hq/pr4rt14n7s31v3f6292wtjm00000gn/T/RackMultipart20180315-1190-ynpy5a.jpg>, @original_filename="image8.jpg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name=\"attachment[image][]\"; filename=\"image8.jpg\"\r\nContent-Type: image/jpeg\r\n">]}}
  Store Load (1.0ms)  SELECT  "stores".* FROM "stores" WHERE "stores"."id" = $1 ORDER BY "stores"."id" ASC LIMIT $2  [["id", 1], ["LIMIT", 1]]
Unpermitted parameter: :image
   (0.2ms)  BEGIN
  SQL (0.7ms)  INSERT INTO "attachments" ("created_at", "updated_at") VALUES ($1, $2) RETURNING "id"  [["created_at", "2018-03-15 09:50:26.308178"], ["updated_at", "2018-03-15 09:50:26.308178"]]
   (0.7ms)  COMMIT

Answer 1

Simon's comment is correct. You need to permit an array of scalar types. In your scenario an ActionDispatch::Http::UploadedFile object, which is accepted as scalar.

http://guides.rubyonrails.org/action_controller_overview.html#strong-parameters

IMO there's no need to set the name on field_form if the attribute is the same: name: 'attachment[image][]' , when you using multiple: true the name property should be set exactly like that.

Also inform which rails version you're using.