展示共同的朋友

Question

我在社交媒体网站上工作，除了共同的朋友，我的一切都在友谊中工作。 我不能让它工作。

这是我的用户模型：

has_many :friendships
has_many :friends, -> { where(friendships: {status: 'accepted'}).order('created_at') }, :through => :friendships
has_many :requested_friends, -> { where(friendships: {status: 'requested'}).order('created_at') }, :through => :friendships, :source => :friend
has_many :pending_friends, -> { where(friendships: {status: 'pending'}).order('created_at') }, :through => :friendships, :source => :friend

友谊模式：

class Friendship < ActiveRecord::Base
  belongs_to :user
  belongs_to :friend, :class_name => 'User', :foreign_key => 'friend_id'

  validates_presence_of :user_id, :friend_id

  # Create a friendship request.
  def self.send_request(user, friend)
    unless user == friend or Friendship.exists?(user, friend)
      transaction do
        create(:user => user, :friend => friend, :status => 'pending')
        create(:user => friend, :friend => user, :status => 'requested')
      end
    end
  end

  # Accept a friend request.
  def self.accept_request(user, friend)
    transaction do
      accept_one_side(user, friend)
      accept_one_side(friend, user)
    end
  end

  # Decline a request, disconnect or cancel a pending request.
  def self.breakup(user, friend)
    transaction do
      destroy(find_by_user_id_and_friend_id(user, friend))
      destroy(find_by_user_id_and_friend_id(friend, user))
    end
  end

  # Return true if the users are (possibly pending) friends.
  def self.exists?(user, friend)
    not find_by_user_id_and_friend_id(user, friend).nil?
  end

  private
  # Update the db with one side of an accepted friendship request.
  def self.accept_one_side(user, friend)
    request = find_by_user_id_and_friend_id(user, friend)
    request.status = 'accepted'
    request.save!
  end
end

我试过这个： rails activerecord，朋友关系+ inverse_friend关系如何获得相互关系？ 包含代码，但我仍然无法使其工作。

谢谢你。

Answer 1

鉴于您有两个用户，他们共同的朋友很简单：

user1.friends & user2.friends

或者这不是你要找的？

这可能会轻而易举地优化它。

user1.friends.where(users: {id: user2.friends.pluck(:id)})

Answer 2

如果您将用户定义为用户a和用户b “共同朋友”，则此方法应该可以解决问题：

class Friendship
  def self.mutual(a,b)
    a.friends.joins('INNER JOIN friendships f2 on friendships.friend_id = f2.friend_id')
             .where('f2.user_id=? and f2.status = ?', b.id, 'accepted')
  end
end

Answer 3

我认为最好像这样创建一个单独的函数

    def mutuals(user)
      a_friends = friends
      b_friends = user.friends
      a_friends.select do |friend|
        b_friends.find_by(friend_id: friend.friend_id)
      end
    end

使用此方法，您可以调用@user.mutual(User.find(3))来查找@user 变量和id 为3 的用户之间的共同朋友