Creating the Friendship Form For Treebook Problems

<div class="page-header">
    <h1><%= @user.full_name%></h1>
    <%= link_to "Add Friend", new_user_friendship_path(friend_id: @user), class: 'btn' %>
</div>
<% if @statuses %>
    <% @statuses.each do |status| %>
    <div class="well">
        <%= status.content %>
        <hr />
        <%= link_to time_ago_in_words(status.created_at), status_path(status) %> ago
        </div>
    <% end %>
<% end %>

<% if @friend %>
    <h1><%= @friend.full_name %></h1>
   <p>Do you really want to friend <%= @friend.full_name %>?</p>
          <%= form_for @user_friendship, method: :post do |form| %>
        <div class="form form-actions">
            <%= form.hidden_field :friend_id, value: @friend %>
            <%= submit_tag "Yes, Add Friend", class: 'but btn-primary' %>
            <%= link_to "Cancel", profile_path(@friend), class: 'btn' %>
        </div>
    <% end %>
<% end %>

class UserFriendshipsController < ApplicationController
    before_filter :authenticate_user!, only: [:new]


def new
    if params[:friend_id]
            @friend = User.where(profile_name: params[:friend_id]).first
            raise ActiveRecord::RecordNotFound if @friend.nil?
            @user_friendship = current_user.user_friendships.new(friend: @friend)
        else
            flash[:error] = "Friend required"
        end
    rescue ActiveRecord::RecordNotFound
        render file: 'public/404', status: :not_found
    end
end

routes.rb

Treebook::Application.routes.draw do
  get "profiles/show"
  devise_for :users

  devise_scope :user do
    get 'register', to: 'devise/registrations#new', as: :register
    get 'login', to: 'devise/sessions#new', as: :login
    get 'logout', to: 'devise/sessions#destroy', as: :logout
  end

  resources :user_friendships

  resources :statuses
  get 'feed', to: 'statuses#index', as: :feed
  root to: 'statuses#index'

  get '/:id', to: 'profiles#show', as: 'profile'

user.rb

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

  # Setup accessible (or protected) attributes for your model
  attr_accessible :email, :password, :password_confirmation, :remember_me,
                  :first_name, :last_name, :profile_name

  validates :first_name, presence: true

  validates :last_name, presence: true

  validates :profile_name, presence: true,
                           uniqueness: true,
                           format: {
                             with: /^[a-zA-Z0-9_-]+$/,
                             message: 'Must be formatted correctly.'
                           }

has_many :statuses
has_many :user_friendships
has_many :friends, through: :user_friendships

  def full_name
    first_name + " " + last_name
  end

  def to_param
    profile_name
  end

  def gravatar_url
    stripped_email = email.strip
    downcased_email = stripped_email.downcase
    hash = Digest::MD5.hexdigest(downcased_email)

    "http://gravatar.com/avatar/#{hash}"

  end
end