Question

I’m getting the following error:

undefined method `email' for nil:NilClass
Extracted source (around line #6):

3:   <div class="post-author">
4:     <div class="post-author-info">
5:       <span class="post-author-name">
6:         <strong><%= link_to comment.user.email, comment.user %></strong>
7:       </span>
8: 
9:       <span class="post-date secondary">

comments.rb:

  def show
    @comment = Comment.find(params[:id])
  end

  def create
    @post = Post.find(params[:post_id])
    comment_attr = params[:comment].merge :user_id => current_user.id
    @comment = @post.comments.create(comment_attr)
    redirect_to post_path(@post)
  end

post.rb:

  attr_accessible :title, :content

  belongs_to :user

  has_many :comments, :dependent => :destroy

user.rb:

 has_many :posts, :dependent => :destroy
  has_many :comments, :dependent => :destroy

comment.rb:

  attr_accessible :content, :user_id

  belongs_to :post, :counter_cache => true
  belongs_to :user

routes.rb:

  resources :posts do
    resources :comments
  end

schema.rb:

 create_table "comments", :force => true do |t|
    t.text     "content"
    t.integer  "post_id"
    t.integer  "user_id"
    t.datetime "created_at", :null => false
    t.datetime "updated_at", :null => false
  end

create_table "users", :force => true do |t|
    t.string   "email",                  :default => "", :null => false
    t.string   "encrypted_password",     :default => "", :null => false
    t.string   "reset_password_token"
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.integer  "sign_in_count",          :default => 0
    t.datetime "current_sign_in_at"
    t.datetime "last_sign_in_at"
    t.string   "current_sign_in_ip"
    t.string   "last_sign_in_ip"
    t.datetime "created_at",                             :null => false
    t.datetime "updated_at",                             :null => false
    t.string   "provider"
    t.string   "uid"
  end

I’m not sure what’s the problem. Everything seems fine in the files above.

Any suggestions?

EDIT:

posts/show.html.erb:

<div id="post-<%= @post.id %>" class="post-single">
  <h3 class="post-title"><%= @post.title %></h3>

  <span class="post-author-name">
    <strong><%= link_to @post.user.email, @post.user %></strong>
  </span>

  <span class="post-content">
    <%= @post.content %>
  </span>

  <div class="comments">
    <h4 class="comments-count"><%= pluralize(@post.comments_count, "Comment") %></h4>

    <%= render @comments %>
    <%= render 'comments/form' %>
  </div>
</div>

comments/_comment.html.erb:

<div id="comment-<%= comment.id %>" class="comment">

  <div class="post-author">
    <div class="post-author-info">
      <span class="post-author-name">
        <strong><%= link_to comment.user.email, comment.user %></strong>
      </span>

      <span class="post-date secondary">
        <%= time_ago_in_words(comment.created_at) %>
      </span>
    </div>

    <span class="post-author-control">
      <% unless current_user == nil %>
        <% if current_user.id == comment.user_id %>
          <%= link_to 'Edit', edit_post_comment_path(@post, comment) %>
        <% end %>
      <% end %>
    </span>
  </div>

  <div class="comment-body">
    <p><%= comment.content %></p>
  </div>
</div>

posts.rb:

  def show

    @post = Post.find(params[:id])
    @comments = @post.comments
    @comment = @post.comments.build
  end

comments/_form.html.erb:

Add a comment:

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

Answer 1

The problem is that the following line in your controller creates a comment object that is related to a post, but not to user and thus causes the error in your partial:

@comment = @post.comments.build

To get rid of the error you should either change the line above to:

@comment = Comment.new

or remove that line from your controller and change your comment form to:

<%= form_for [@post, Comment.new] do |f| %>