I am trying to upload files using a Rails form where the remote is set to true. I'm using Rails 4.1.1. Let's say that my model is a Message, and it is using JavaScript so that the user could easily send multiple messages without reloading the page. The form is set like this:
<%= form_for @message, url: {action: "create"}, html: {:class => "message-form", multipart: true}, remote: true do |f| %>
The user can upload images with the Message, if they wish to do so. MessageImage acts as a nested attribute in the form, and is declared like this (http://railscasts.com/episodes/196-nested-model-form-revised way):
<%= f.fields_for :message_images do |builder| %>
<%= render 'message_image_fields', f: builder %>
<%= link_to_add_fields "Add an image", f, :message_images %>
<% end %>
On my controller the action is roughly like this:
if @message.save
flash.now[:success] = "Message sent"
else
flash.now[:alert] = "Error sending the message"
end
respond_to do |format|
format.html { render 'new' }
format.js { render 'new' }
end
Now, this works perfectly as long as the user doesn't send any images, but if they do, it uses format.html instead of format.js. Removing the format.html gives ActionController::UnknownFormat-exception.
Now, this obviously has to do with the fact that you can't submit files with remote set to true. I tried searching a bit, and found this gem https://github.com/JangoSteve/remotipart , which seems to be exactly what I'm looking for. I installed it following the instructions, but for some reason it still doesn't work and gives ActionController::UnknownFormat-exception if I remove the format.html. However, I couldn't find any example of it involving nested attributes. Are there any alternatives for this gem or any other way to fix this, or should I just set that it renders HTML if the user submits files?