has_many through instead of join query - sql

Question

I have relationship between User models defined through Friendship model. (ROR 4)
User
class User < ActiveRecord::Base
has_many :friendships, ->(object) { where('user_id = :id OR friend_id = :id', id: object.id) }
has_many :friends, ->(object) { where(friendships: {status: 'accepted'}).where('user_id = :id OR friend_id = :id', id: object.id) }, through: :friendships, source: :friend
has_many :requested_friends, -> { where(friendships: {status: 'pending'}) }, through: :friendships, source: :friend
end
Friendship
class Friendship < ActiveRecord::Base
belongs_to :user
belongs_to :friend, class_name: 'User'
def self.request(user, friend)
unless user == friend or find_friendship(user, friend) != nil
create(user: user, friend: friend, status: 'pending')
end
end
def self.find_friendship(user, friend)
ids = [user.id, friend.id]
where(user_id: ids, friend_id: ids).first
end
end
However, this does not work and my tests are failing because of SQL queries produced.
Friendships relation
> user.friendships
Query:
SELECT "friendships".* FROM "friendships"
WHERE "friendships"."user_id" = ?
AND (user_id = 1 OR friend_id = 1) [["user_id", 1]]
So part of WHERE before AND "kills" my actual where. I made a workaround by making instance method:
def friendships
self.class
.select('friendships.* FROM `friendships`')
.where('user_id = :id OR friend_id = :id', id)
end
Is there a way I can remove my instance method and modify has_many relation to produce the SQL I want?
Requested_friends relation
> Friendship.request(user, friend)
> friend.requested_friends
Query:
SELECT "users".* FROM "users"
INNER JOIN "friendships" ON "users"."id" = "friendships"."friend_id"
WHERE "friendships"."status" = 'pending'
AND "friendships"."user_id" = ?
AND (user_id = 2 OR friend_id = 2) [["user_id", 2]]
It obviously isn't what I need so I made a workaround by removing has_many :requested_friends and making an instance method:
def requested_friends
self.class
.joins('JOIN `friendships` friendships ON users.id = friendships.user_id')
.where('friendships.status = ?', 'pending')
.where('friendships.friend_id = ?', id)
end
Is there any way I can modify my has_many :requested_friends relation to produce same SQL as my instance method?

Answer 1

Very confusing - I'd do something like this:
#app/models/user.rb
Class User < ActiveRecord::Base
has_many :friendships, class_name: "user_friendships", association_foreign_key: "user_id", foreign_key: "friend_id",
has_many :friends, class_name: "User", through: :friendships
end
#app/models/user_friendship.rb
Class UserFriendship < ActiveRecord::Base
belongs_to :user
belongs_to :friend, class_name: "User"
end
You'd have a join table which looks like this:
user_friendships
id | user_id | friend_id | other | info | created_at | updated_at
This should work (I'm not sure about the self referential association). If it does, it will allow you to call:
#user.friends
I hope this helps?
You might also benefit from this gem

Answer 2

you cannot achieve the SQL you want using has_many method with condition. The reason is that the block you pass to the method is only additional condition, on top of the standard query which checks if user_id = ?.
Instead you can simplify your instance method a little bit
def friendships
Friendship.where('user_id = :id or friend_id = :id', id)
end