Rails Forum Tutorial for Beginners(Part 2 of 3)

This is part 2 of my Rails 2.0 Forum tutorial for beginners. You can find part 1 here. Last time, we created our Forum, Topic, and Reply objects. We nested topics inside of forums and adjusted the views/controllers to allow for the nesting. This time, we will take care of replies being nested in a topic.

The nesting in /config/routes.rb has already been taken care of in the first tutorial:

  map.resources :topics, :has_many => :replies

The first thing we are going to do is to create partials for /app/views/replies/new.html.erb and /app/views/replies/edit.html.erb. Create the file /app/views/replies/_reply.html.erb

#/app/views/replies/_reply.html.erb

<% form_for([@topic, @reply]) do |f| %>
  <p>
    <b>Subject</b><br />
    <%= f.text_field :subject %>
  </p>

  <p>
    <b>Body</b><br />
    <%= f.text_area :body %>
  </p>

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

And now change edit and new to:

#/app/views/replies/edit.html.erb

<h1>Editing reply</h1>

<%= error_messages_for :reply %>

<%= render :partial => @reply, :locals => { :button_name => "Submit" } %>

<%= link_to 'Show', [@topic, @reply] %> |
<%= link_to 'Back', replies_path %>

#/app/views/replies/new.html.erb

<h1>New reply</h1>

<%= error_messages_for :reply %>

<%= render :partial => @reply, :locals => { :button_name => "Reply" } %>

<%= link_to 'Back', replies_path %>

Same stuff we did last time...
Now lets go to /app/controllers/replies_controller.rb
Add this at the top, to make sure a topic gets loaded everytime the replies controller is used:

  before_filter :load_topic
  
  def load_topic
    @topic = Topic.find(params[:topic_id])
  end  

inside the new function change the line:

    @reply = Reply.new

to this:

    @reply = @topic.replies.build

Change the edit function:

#old edit function

  def edit
    @reply = Reply.find(params[:id])
  end

#new edit function

  def edit
    @reply = @topic.replies.find(params[:id])
  end

Change the create function:

#old create

  def create
    @reply = Reply.new(params[:reply])

    respond_to do |format|
      if @reply.save
        flash[:notice] = 'Reply was successfully created.'
        format.html { redirect_to(@reply) }
        format.xml  { render :xml => @reply, :status => :created, :location => @reply }
      else
        format.html { render :action => "new" }
        format.xml  { render :xml => @reply.errors, :status => :unprocessable_entity }
      end
    end
  end

#new create

  def create
    @reply = @topic.replies.build(params[:reply])

    respond_to do |format|
      if @reply.save
        flash[:notice] = 'Reply was successfully created.'
        format.html { redirect_to([Forum.find(@topic.forum_id), @topic]) }
        format.xml  { render :xml => @reply, :status => :created, :location => @reply }
      else
        format.html { render :action => "new" }
        format.xml  { render :xml => @reply.errors, :status => :unprocessable_entity }
      end
    end
  end

Notice the change in redirect_to...after a reply to a topic is submitted, I want to send the user back to the forum the topic was in, to get the forum, I had to use the find function and pass it the forum_id of the topic and the topic.


In the update and destroy functions:

#old update and destroy

  def update
    @reply = Reply.find(params[:id])

    respond_to do |format|
      if @reply.update_attributes(params[:reply])
        flash[:notice] = 'Reply was successfully updated.'
        format.html { redirect_to(@reply) }
        format.xml  { head :ok }
      else
        format.html { render :action => "edit" }
        format.xml  { render :xml => @reply.errors, :status => :unprocessable_entity }
      end
    end
  end

  def destroy
    @reply = Reply.find(params[:id])
    @reply.destroy

    respond_to do |format|
      format.html { redirect_to(replies_url) }
      format.xml  { head :ok }
    end
  end
  

#new update and destroy

  def update
    @reply = @topic.replies.find(params[:id])

    respond_to do |format|
      if @reply.update_attributes(params[:reply])
        flash[:notice] = 'Reply was successfully updated.'
        format.html { redirect_to(@topic) }
        format.xml  { head :ok }
      else
        format.html { render :action => "edit" }
        format.xml  { render :xml => @reply.errors, :status => :unprocessable_entity }
      end
    end
  end


  def destroy
    @reply = @topic.replies.find(params[:id])
    @reply.destroy

    respond_to do |format|
      format.html { redirect_to(@topic) }
      format.xml  { head :ok }
    end
  end

Now that we have all of that done...lets head over to /app/views/topics/show.html.erb so we can display our replies and the form for a new reply.


In addition to showing replies and a form for a new one, I changed the formatting a little, so here are the contents on show.html.erb

<p>
  <h3>Forum: - <%=h @forum.name %></h3>
</p>

<p>
  <b><%=h @topic.subject %></b>
</p>

<p>
  <%=h @topic.body %>
</p>

<% unless @topic.replies.empty? %>

  <% @topic.replies.each do |reply| %>
      <p>
        <b><%= reply.subject %></b>    
      </p>
      <p>
        <%=h reply.body %>
      </p>
    
  <% end %>
<% end %>

<h2>Reply</h2>
<%= render :partial => @reply = Reply.new, :locals => { :button_name => 'Reply' } %>

<%= link_to 'Edit', edit_forum_topic_path(@forum, @topic) %> |
<%= link_to 'Back', topics_path %>

Since this is the same stuff we were doing in the first tutorial, I won't bother explaining any of it...you should be able to tell what is going on. Feel free to leave a comment if you do have any questions.


Now, fire up the web server and head to localhost:3000/forums/1/topics/1 (assuming you have a topic already created).






And create a couple of replies:





And thats it! (10 points go to anyone who catches the video game reference in reply #2 in the screenshot).

In this tutorial, we nested replies inside of a topic, and set the views/controllers accordingly. Next time, we will take a look at authentication using the RESTful authentication plug-in and acts_as_state_machine plugin.

Feel free to leave comments, and link me from your site. See you next time!