Question

I have three models User, Post, Vote

I need to doesn’t allow user to vote for his own post.
How I can make this in my models and test this in Rspec?

Post Model:

class Post < ActiveRecord::Base
  attr_accessible :title, :main_text, :video, :photo, :tag

  validates :title,     presence: true, length:  {minimum: 1, maximum: 200}
  validates :main_text, presence: true, length:  {minimum: 1}

  belongs_to :user
  has_many   :votes

end

User Model:

class User < ActiveRecord::Base
  attr_accessible :name, :email, :bio

  has_many :posts
  has_many :votes

  validates :name,  presence: true, length: {minimum: 1, maximum: 120}
  validates :email, presence: true, length: {minimum: 5, maximum: 250}, uniqueness: true, 
                    format: {:with => /^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/i}


end

Vote model:

class Vote < ActiveRecord::Base

  attr_accessible :user_id, :post_id, :units

  belongs_to :user
  belongs_to :post

  validates :post_id, uniqueness: {scope: :user_id}  #does not allow user to vote for the same post twice


end

My spec test for Vote:

require 'spec_helper'

describe Vote do

  it "does not allow user to vote for the same post twice" do 
    user = User.create(name: "Nik", email: "[e-mail]" )
    post = Post.create(title: "New Post", main_text: "Many, many, many...")
    vote1 = Vote.create(user_id: user.id, post_id: post.id)  
    vote1.errors.should be_empty    
    vote2 = Vote.create(user_id: user.id, post_id: post.id)        
    vote2.errors.should_not be_empty      
  end 

  it "does not allow user to vote for his own post" do
    user = User.create(name:"Nik", email:"[e-mail]")
    post = Post.create(user_id: user.id, title: "New Post", main_text: "Many, many, many...")
    vote1 = Vote.create(user_id: user.id, post_id: post.id)
    vote1.errors.should_not be_empty
  end

end

Answer 1

I’ve not tested the following code so it could not work or even kill your cats but try with a custom validation with add an error if the vote’s user is the same of the post’s user.

Note I return if the user or the post are nil for obvius reasons.

# In your vote model
validate :users_cant_vote_their_posts

def users_cant_vote_their_posts
  return if user.nil? or post.nil?
  if user_id == post.user_id
    errors[:base] = "A user can't vote their posts"
  end
end

EDIT: Here a possible test, here I’m using FactoryGirl to generate votes. Again this code is not tested (sorry for the pun)

describe Vote do
  subject { vote }

  let!(:vote) { FactoryGirl.build(:vote) }

  it 'from factory should be valid' do
    should be_valid
  end

  context 'when user try to double vote' do
    before do
      # Create another vote from user to post
      FactoryGirl.create(:vote, :user => vote.user, :post => vote.post)
    end

    it { should_not be_valid }
  end

  context 'when user try to vote his posts' do
    before do
      # Set the user whom voted to the post's owner
      vote.user = vote.post.user
    end

    it { should_not be_valid }
  end

end