"param is missing or the value is empty:" Paperclip no file selected - Rails

Question

I am building a photo gallery application that allows users to attach multiple photos to each of their galleries. I am using Paperclip to handle file uploads.

The below code works fine until [Upload] is clicked on the form with no file selected. As I understand it, it is getting stuck at the controller before it is handed over to the Photo model to run it's presence, file-type and file-size validations.

The error received when clicking [Upload] with no file selected is: "param is missing or the value is empty: photo" Extracted source has photo#photo_params line highlighted.

Gallery model:

class Gallery < ActiveRecord::Base
  belongs_to :user
  has_many :photos
end

Photo model:

class Photo < ActiveRecord::Base
  belongs_to :user
  belongs_to :gallery

  has_attached_file :photo,
    s3_permissions: :private

  validates_attachment :photo,
    presence: true,
    content_type: {
      content_type: [
        "image/jpeg", # JPEG/JPG
        "image/png" # PNG
        ] },
    size: { in: 0..5.megabytes }
end

Controller action (photos#create):

  def create
    @photo = Photo.new(photo_params)
    @photo.gallery_id = @gallery.id
    @photo.user_id = current_user.id

    if @photo.save
      flash[:success] = "Photo successfully saved."
      redirect_to gallery_path(@photo.gallery)
    else
      flash[:error] = "The photo upload failed! Make sure the file you're trying to upload is of a supported type (JPG, JPEG or PNG) and try again."
      redirect_to gallery_path(@photo.gallery)
    end
  end

Strong Params (photos#photo_params):

def photo_params
  params.require(:photo).permit(:photo)
end

Upload form:

<%= form_for Photo.new, url: gallery_photos_path(@gallery) do |f| %>
    <%= f.label :photo %>
    <%= f.file_field :photo %>

    <%= f.submit "Upload" %>
  <% end %>

I realise that using Model.new in the form is probably not a best-practice but because the form is loaded as a partial on galleries#show view, it was the only way i could get it going.

I am also thinking that having the model named :photo and the actual Paperclip attachment also named :photo may also be causing an issue. Is this correct?

Does anyone know what's going on here?

angkiki angkiki · Accepted Answer · 2016-09-30T05:23:41

Yes i think like you mentioned you should rename your paperclip attachment though i'm not sure if it causes any issues, having code like photo_params.require(:photo).permit(:photo) cant be any good.

Additionally for your else condition in create, try redirecting to root_path first. I think your route may be wrong since your @photo instance variable is actually Photo.new.

Hope it helps a! Im not a rails expert. Cheers.

"param is missing or the value is empty:" Paperclip no file selected - Rails

3 Answers