Question

I’ve been trying to implement a commenting system for my Rails app. Every event in my app has it’s own page, and on the page is a comments thread. I want users to be able to submit comments using ajax. I have tried to follow RailsCast 136, which is basically what I want to have work in my app. However, whenever I post a comment, the ajax request is not going through, and I’m receiving the error:

Started POST “/events/undefined” for 127.0.0.1 at 2011-07-17 00:39:16
-0400

ActionController::RoutingError (No route matches “/events/undefined”):

Here’s the code for my show action in my events_controller.

 def show
 @event = Event.find(params[:id])
 @comment = Comment.new     
 session[:event_id] = @event.id     
 @comments = @event.comments.reverse
 end

Here’s the code for my comment form in my event show view.

<div id="commentform">  <%= form_for(@comment, :remote => true) do |f| %>   

<% if signed_in? %>
<p><%= f.label :author %><br />
<%= f.text_field :author, :value => current_user.name %></p>

<% else %>
<p><%= f.label :author %><br />
<%= f.text_field :author %></p>

<% end %>

       <p><%= f.label :content %><br />
       <%= f.text_field :content %></p>

       <p><%= f.submit %></p>   <% end %> </div>

Here’s the code for my create action in my comments_controller.

def create
  @comment = Comment.create!(params[:comment])
  @comment.event_id = session[:event_id]
  session[:event_id] = nil
  flash[:success] = "Comment sent!"
  respond_to do |format|
    format.html { redirect_to @comment.event }
    format.js
  end   
  end

Here’s the jQuery code for posting with ajax. It is pretty much the same as the code outlined by RailsCast 136

jQuery.ajaxSetup({  'beforeSend': function(xhr)
{xhr.setRequestHeader("Accept", "text/javascript")} })

$(document).ready(function(){   $("#commentform").submit(function(){
       $.post($(this).attr("action"), $(this).serialize(), null, "script");
       return false;    }) })

Anybody have any idea what could be going wrong? I’m very new to Rails and web development in general and appreciate any help fixing this.

---

EDIT -: I managed to fiddle around and fix the problem. I essentially followed the solution that vinceh laid out in addition to nesting my routes and got it to work. Thanks guys.

Thanks so much,
Sid

Answer 1

I see 2 things right on top. First you are not specifying where the form is sent to. So you need to change that to

<%= form_for @comment, :url => {:controller => :comments, :action => :create}, :remote => true do |f| %> 

    <% if signed_in? %>

    <%= f.label :author %>
    <%= f.text_field :author, :value => current_user.name %>

    <% else %>

    <%= f.label :author %>
    <%= f.text_field :author %>

    <% end %>

    <p><%= f.label :content %><br />
    <%= f.text_field :content %></p>

    <p><%= f.submit %></p> 
<% end %> 

Then you need to add the appropriate route in your routes.rb folder, ie

match "comments/create" => "comments#create"

See if that produces something new. Let me know and I’ll keep updating this answer.

If you want a good comments AJAX tutorial, read this!

Good luck!