Rails 3 javascript: How to render a partial with parameters

Question

I'm still getting the hang of Rails. Here I'm using Rails 3 and the goal basically is to have an AJAX call triggered when I click the subscribe button the post_form partial is rendered beneath for the topic I have just subscribed to. The button then becomes an unsubscibe button and the post_form partial is removed. The toggling of the button alone works (i.e: by removing the second line in the two immediately following snippets), but the rendering of the *post_form* partial does not.

The problem is I can't seem to get the right syntax and/or passing of parameters in the two following partials. The topic object is just not passed and I get an invalid model_name for NilClass error when clicking on the subscribe or unsubscribe button. If I refresh the page manually, the partial is rendered or hidden the correct way, so it's really just the AJAX part that isn't working right.

views/subscription/create.js.erb

$("#subscription_form").html("<%= escape_javascript(render('users/unsubscribe')) %>");
$("#post_form").html("<%= escape_javascript(render('shared/post_form', :topic => @topic)) %>");

views/subscription/destroy.js.erb

$("#subscription_form").html("<%= escape_javascript(render('users/subscribe')) %>");
$("#post_form").html("<%= escape_javascript(render('shared/post_form', :topic => @topic)) %>");

views/users/_subscription_form.html.erb

<% unless current_user?(@user) %>
  <div id="subscription_form">
  <% if current_user.subscribed?(@topic) %>
    <%= render 'users/unsubscribe', :topic => @topic %>
  <% else %>
    <%= render 'users/subscribe', :topic => @topic %>
  <% end %>
  </div>
<% end %>

controllers/subscriptions_controller.rb

class SubscriptionsController < ApplicationController
      before_filter :signed_in_user

      respond_to :html, :js

      def create
        @topic = Topic.find(params[:subscription][:topic_id])
        current_user.subscribe!(@topic)
        respond_with @topic
      end

      def destroy
        @topic = Subscription.find(params[:id]).topic
        current_user.unsubscribe!(@topic)
        respond_with @topic
      end
   end

views/shared/_post_form.html.erb

<%= form_for(@post) do |f| %>
  <div class="field">
    <%= f.hidden_field :topic_id, :value => @topic.id %>
    <%= f.text_area :content, placeholder: "Tell us about it ..." %>
  </div>
  <%= f.submit "Post", class: "btn btn-large btn-primary" %>
<% end %>

If it is of any help, the relationships are:

post -> belongs_to -> topic and topic -> has_many -> posts

Is there a reason why you're doing a "respond_with @topic"? You should be able to leave those lines out since you have named your views conventionally. — awbergs
– awbergs, Commented Jul 20, 2012 at 19:15

awbergs · Accepted Answer · 2012-07-20 19:22:52Z

3

Looks like you're using the variable "@post" in the "views/_post_form.html.erb" file.

<%= form_for(@post) do |f| %>

Since you aren't setting that variable anywhere in your actions you would get a null reference error.

You would need to do something like this:

def create
  @post = Post.find(the_post_id)
  @topic = Topic.find(params[:subscription][:topic_id])
  current_user.subscribe!(@topic)
  respond_with @topic
end

Also you are passing in the "topic" variable as a local but accessing it as an instance variable. You should change the your _post_form.html.erb file to look like this:

<%= form_for(@post) do |f| %>
  <div class="field">
    <%= f.hidden_field :topic_id, :value => topic.id %>
    <%= f.text_area :content, placeholder: "Tell us about it ..." %>
  </div>
  <%= f.submit "Post", class: "btn btn-large btn-primary" %>
<% end %>

I don't have my ruby environment readily available so I can't verify that this will solve your problem but I think it should move you in the right direction.

answered Jul 20, 2012 at 19:22

awbergs

9524 silver badges15 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

IanBussieres Over a year ago

Environment or not, you nailed it. Thanks.

Collectives™ on Stack Overflow

Rails 3 javascript: How to render a partial with parameters

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related