has_friends

ATTENTION: This is a new simpler implementation. If you want to use the previous version, get the 1.0 tag.

Instalation

Install the plugin with

script/plugin install git://github.com/fnando/has_friends.git

Then generate a migration with script/generate migration create_friendships and add the following code:

class CreateFriendships < ActiveRecord::Migration
  def self.up
    create_table :friendships do |t|
      t.references :user, :friend
      t.datetime :requested_at, :accepted_at, :null => true, :default => nil
      t.string :status
    end

    add_index :friendships, :user_id
    add_index :friendships, :friend_id
    add_index :friendships, :status
  end

  def self.down
    drop_table :friendships
  end
end

Finally, run the migrations with rake db:migrate

Usage

Add the method call has_friends to your model.

class User < ActiveRecord::Base
  has_friends
end

john = User.find_by_login 'john'
mary = User.find_by_login 'mary'
paul = User.find_by_login 'paul'

# john wants to be friend with mary
# always return a friendship object
john.be_friends_with(mary)

# are they friends?
john.friends?(mary)

# get the friendship object
john.friendship_for(mary)

# mary accepts john's request if it exists;
# makes a friendship request otherwise.
mary.be_friends_with(john)

# check if paul is mary's friend
mary.friends?(paul)

# check if an user is the current user, so it can
# be differently presented
mary.friends.each {|friend| friend.is?(current_user) }

# if you're dealing with a friendship object,
# the following methods are available
friendship.accept!

# if you're using has_paginate plugin, you can use it:
mary.friends.paginate(:page => 3, :limit => 10)

# the be_friends_with method returns 2 params: friendship object and status.
# the friendship object will be present only when the friendship is created
# (that is, when is requested for the first time)
# STATUS_ALREADY_FRIENDS		 # => users are already friends
# STATUS_ALREADY_REQUESTED		 # => user has already requested friendship
# STATUS_IS_YOU					 # => user is trying add himself as friend
# STATUS_FRIEND_IS_REQUIRED      # => friend argument is missing
# STATUS_FRIENDSHIP_ACCEPTED     # => friendship has been accepted
# STATUS_REQUESTED				 # => friendship has been requested

friendship, status = mary.be_friends_with(john)

if status == Friends::STATUS_REQUESTED
  # the friendship has been requested
  Mailer.deliver_friendship_request(friendship)
elsif status == Friends::STATUS_ALREADY_FRIENDS
  # they're already friends
else
  # ...
end

NOTE: You should have a User model. You should also have a friends_count column on your model. Otherwise, this won't work! Create a new migration with script/generate migration add_friends_count_to_user:

class AddFriendsCountToUser < ActiveRecord::Migration
  def self.up
    add_column :users, :friends_count, :integer, :default => 0, :null => false
  end

  def self.down
    remove_column :users, :friends_count
  end
end

LICENSE:

(The MIT License)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.