_comments.html.erb

<p>
  <b>Comment:</b>
  <%= comment.body %>
</p>

<p>
<%= link_to 'Destroy Comment', [comment.post, comment],
	:confirm => 'Are you sure?',
	:method => :delete %>
</p>

comment_form.html.erb

<%= form_for([@post, @post.comments.build]) do |f| %>
  <div class="field">
    <%= f.label :commenter %><br />
    <%= f.text_field :commenter %>
  </div>
  <div class="field">
    <%= f.label :body %><br />
    <%= f.text_area :body %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

models.rb

class Group < ActiveRecord::Base
  attr_accessible :affiliation, :group_name, :group_type, :string

  validates :group_name, :presence => true
  has_many :posts, :dependent => :destroy
  accepts_nested_attributes_for :posts
end

class Post < ActiveRecord::Base
  attr_accessible :body, :posted_by, :posted_by_uid

  validates :body, :presence => true

  belongs_to :group
  has_many :comments, :dependent => :destroy

end

# added "group_id" through migration


class Comment < ActiveRecord::Base
  belongs_to :post
  attr_accessible :body, :commenter
end

posts_views.html.erb

Group Show

<p>
	<b> Group Type </b>
	<%= @group.group_type %>
</p>

<h1>New post</h1>
<%= render 'posts/form' %>

<p>
	<b>Posts</b>
	<%= render @group.posts %>
</p>

Posts partial 

<%= form_for(@post) do |f| %>
  <% if @post.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@post.errors.count, "error") %> prohibited this post from being saved:</h2>

      <ul>
      <% @post.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

   <div class="field">
    <%= f.label :body %><br />
    <%= f.text_area :body %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

Posts Show

<p id="notice"><%= notice %></p>

<p>
	<b> Content </b>
	<%= @post.body %>
</p>

<h2>Comments</h2>
<%= render @post.comments %>
  
<h2>Add a comment:</h2>
<%=	 render "comments/form" %>
<br />

Posts Form