NoMethodError in Pages#profile - ruby-on-rails

Question

I'm working on build a Twitter-like sample app, but I am stuck at creating a following method. I have created a Relationship model and the necessary classes to accomplish the task, but when I load the page, I receive the error "NoMethodError" on this line: <%= form_for(current_user.active_relationships.build, remote: true) do |f| %>
I render the form on the profile page like so:
<%= render '/components/follow_button', :user => User.find_by_username(params[:id]) %>
Here is the form:
<% if current_user.id != user.id %>
<div class="col s12">
<div class="panel panel-default">
<% if !current_user.following?(user) %>
<%= form_for(current_user.active_relationships.build, remote: true) do |f| %>
<div><%= hidden_field_tag :followed_id, user.id %></div>
<%= f.submit "Follow", class: "btn btn-primary" %>
<% end %>
<% else %>
<%= form_for(current_user.active_relationships.find_by(followed_id: user.id),
html: { method: :delete }) do |f| %>
<%= f.submit "Unfollow", class: "btn" %>
<% end %>
<% end %>
</div>
</div>
<% end %>
User.rb:
class User < ActiveRecord::Base
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable
validates_uniqueness_of :email, :case_sensitive => false
validates_uniqueness_of :username, :case_sensitive => false
has_many :posts, dependent: :destroy
has_many :active_relationships, class_name: "Relationship", foreign_key: "follower_id", dependent: :destroy
has_many :passive_relationships, class_name: "Relationship", foreign_key: "followed_id", dependent: :destroy
has_many :following, through: :active_relationships, source: :followed
has_many :followers, through: :passive_relationships, source: :follower
def follow(other)
active_relationships.create(followed_id: other.id)
end
def unfollow(other)
active_relationships.find_by(followed_id: other.id).destroy
end
def following?(other)
following.include?(other)
end
end
Relationship.rb
class Relationship < ActiveRecord::Base
belongs_to :follower, class_name: "User"
belongs_to :followed, class_name: "User"
validates :follower_id, presence: true
validates :followed_id, presence: true
end
RelationshipsController:
class RelationshipsController < ApplicationController
def create
user = User.find(params[:followed_id])
current_user.follow(user)
redirect_to(:back)
end
def destroy
user = Relationship.find(params[:id]).followed
current_user.unfollow(user)
redirect_to(:back)
end
end
Any help would be greatly appreciated.
EDIT: Following method used in Routes.rb
devise_for :users
resources :users do
member do
get :following, :followers
end
end

Answer 1

On the form_for documentation, it eventually talks about 'Resource-oriented style' forms
In the examples just shown, although not indicated explicitly, we still need to use the :url option in order to specify where the form is going to be sent. However, further simplification is possible if the record passed to form_for is a resource, i.e. it corresponds to a set of RESTful routes, e.g. defined using the resources method in config/routes.rb. In this case Rails will simply infer the appropriate URL from the record itself
<%= form_for(Post.new) do |f| %>
...
<% end %>
is equivalent to something like:
<%= form_for #post, as: :post, url: posts_path, html: { class: "new_post", id: "new_post" } do |f| %>
...
<% end %>
Looking at your code, since you are not passing a :url option to form_for and you are passing an instance of a model, it's assuming your model was configured in the routes file with resources :relationships, which generates some named route helpers such as relationships_path, the method that it's complaining is missing.
To fix your problem, you need to pass form_for a :url where your controller lives and where it should post to, or update your routes to use the resources :relationships. You can read more information about the resources routing here. If you add
resources :relationships, only: [:create, :destroy]
outside of your devise_for block, you'll end up with 2 new routes for
Prefix Verb URI Pattern Controller#Action
relationships POST /relationships(.:format) relationships#create
relationship DELETE /relationships/:id(.:format) relationships#destroy
and the named helpers relationships_path and relationship_path which your 2 form_for tags are going to be looking for.
Don't forget to restart your server after making changes to your config/routes.rb file to make sure rails picks them up.