Pieces of Rails App that is Giving no "name" method error

post.rb

# Post Model
class Post < ActiveRecord::Base
  belongs_to :user
  validates :title, :presence => true
  validates :content, :presence => true
end

show.html.erb

# ERB view for show Post
<article>
  <header>
    <h2><%= @post.title %></h2>
    <h3>Post by <%= @post.user.name %></h3>
  </header>
  <section>
    <%= @post.content %>
  </section>
</article>

<nav>
  <% if user_is_admin? %>
  <%= link_to 'Edit', edit_post_path(@post) %>
  <%= link_to 'Remove', @post, confirm: 'Are you sure you want to remove this post?', method: :delete %>
  <% end %>
  <%= link_to 'Back', posts_path %>
</nav>

user.rb

# User Model (devise)
class User < ActiveRecord::Base
  # Include default devise modules. Others available are:
  # :token_authenticatable, :encryptable, :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable,
         :confirmable

  # Setup accessible (or protected) attributes for your model
  attr_accessible :name, :email, :password, :password_confirmation, :remember_me
  
  has_many :posts
  
  def admin?
    self.admin
  end
end