I want to order a has_many through relationship on a column in the through table
class DoctorProfile
has_many :doctor_specialties
has_many :specialties, through: :doctor_specialties
class Specialty
has_many :doctor_specialties
has_many :doctor_profiles, through: :doctor_specialties
class DoctorSpecialty
belongs_to :doctor_profile
belongs_to :specialty
I'd like the doctor specialties to be ordered by the column ordinal on DoctorSpecialty. Specifically this error happens when using includes
DoctorProfile.includes(:specialties).all
I've tried
has_many :specialties, -> { order 'doctor_specialties.ordinal' }, through: :doctor_specialties
DoctorProfile Load (0.6ms) SELECT "doctor_profiles".* FROM "doctor_profiles" ORDER BY "doctor_profiles"."id" ASC LIMIT $1 [["LIMIT", 1]]
DoctorSpecialty Load (0.8ms) SELECT "doctor_specialties".* FROM "doctor_specialties" WHERE "doctor_specialties"."doctor_profile_id" = 1
Specialty Load (0.4ms) SELECT "specialties".* FROM "specialties" WHERE "specialties"."id" = 69 ORDER BY doctor_specialties.ordinal
and receieve a missing FROM -clause error PG::UndefinedTable: ERROR: missing FROM-clause entry for table "doctor_specialties"
How can I define the order on the through table so specialties are returning in ascending order?
Note:
I was able to get this working by adding a default_scope to DoctorSpecialty
default_scope { order('ordinal ASC') }
However, I'm still wondering if there is a way to do it on the has_many through
I was able to get it working using
class DoctorProfile
has_many :specialties, -> { order 'doctor_specialties.ordinal' }, through: :doctor_specialties
end
class DoctorSpecialty < ApplicationRecord
belongs_to :doctor_profile
belongs_to :specialty
default_scope { order('ordinal ASC') }
end
Not sure if this is what's causing your error but you haven't completed the has many through relationship on the Specialty side. Should be has_many :doctor_profiles, through: :doctor_specialties
Also for this line in DoctorProfiles has_many :specialties, through: doctor_specialties, doctor_specialties needs to be a symbol
As for the ordering I think you need to do a joins instead of an includes
like DoctorProfile.joins(:doctor_specialties).order("doctor_specialties.ordinal ASC")
Related
I have m:n association with counter cache. I want delete user and remove appropriate records from the users_items association. The sql query which should remove records from users_items association is wrong.
class User < ApplicationRecord
has_many :users_items, class_name: 'UsersItem', dependent: :destroy
has_many :items, through: :users_items
end
class Item < ApplicationRecord
has_many :users_items, class_name: 'UsersItem', dependent: :destroy
has_many :users, through: :users_items
end
class UsersItem < ApplicationRecord
belongs_to :user, counter_cache: true
belongs_to :item, counter_cache: true
end
u = User.last
u.destroy
(0.3ms) BEGIN
UsersItem Load (0.4ms) SELECT "users_items".* FROM "users_items" WHERE "users_items"."user_id" = $1 [["user_id", 41]]
UsersItem Destroy (1.9ms) DELETE FROM "users_items" WHERE "users_items"."" IS NULL
(0.3ms) ROLLBACK
ActiveRecord::StatementInvalid (PG::SyntaxError: ERROR: zero-length delimited identifier at or near """")
LINE 1: DELETE FROM "users_items" WHERE "users_items"."" IS NULL
The problem was with the users_items table. The table was created without primary key. It started working when I added the primary id.
Myth
I am building matching system between users, originally it was has and belongs to many association, but due to some validations and additional data i need for that join table, i need to have model for that one, and change it to has many through.
has_and_belongs_to_many(:likes,
class_name: :User,
join_table: :user_likes,
foreign_key: :user_liker_id,
association_foreign_key: :user_liked_id)
has_and_belongs_to_many(:likeds,
class_name: :User,
join_table: :user_likes,
foreign_key: :user_liked_id,
association_foreign_key: :user_liker_id)
This is old implementation which needs to be converted to has_many through. As you can see, with this one i can retrieve all users which i liked and users which liked me. I have created UserLike model but i don't have any success with making it workable inside user model. What i already tried is following:
user.rb
has_many :user_likes
has_many :likes, through: :user_likes, foreign_key: :user_liked_id
has_many :likeds, through: :user_likes, foreign_key: :user_liker_id
user_like.rb
class UserLike < ApplicationRecord
belongs_to :user
end
This implementation raises following exception:
ActiveRecord::HasManyThroughSourceAssociationNotFoundError: Could not find the source association(s) "like" or :likes in model UserLike. Try 'has_many :likes, :through => :user_likes, :source => '. Is it one of user or user_likes?
I don't know what i am missing here, any help would be appreciated :)
When creating a join table that joins the same table twice you need two separate associations since the user can be in either foreign key:
class User < ApplicationRecord
has_many :likes_as_liker,
class_name: 'Like',
foreign_key: 'liker_id'
has_many :likes_as_liked,
class_name: 'Like',
foreign_key: 'liked_id'
end
class Like < ApplicationRecord
belongs_to :liker, class_name: 'User'
belongs_to :liked, class_name: 'User'
end
With our two has_many associations done we can start creating indirect associations:
class User < ApplicationRecord
has_many :likes_as_liker,
class_name: 'Like',
foreign_key: 'liker_id'
has_many :likes_as_liked,
class_name: 'Like',
foreign_key: 'liked_id'
has_many :likers,
through: :likes_as_liked
has_many :liked_users,
through: :likes_as_liker,
source: :liked
end
Which works perfectly:
irb(main):002:0> u.likers
User Load (2.8ms) SELECT "users".* FROM "users" INNER JOIN "likes" ON "users"."id" = "likes"."liker_id" WHERE "likes"."liked_id" = $1 LIMIT $2 [["liked_id", 1], ["LIMIT", 11]]
=> #<ActiveRecord::Associations::CollectionProxy []>
irb(main):003:0> u.liked_users
User Load (1.3ms) SELECT "users".* FROM "users" INNER JOIN "likes" ON "users"."id" = "likes"."liked_id" WHERE "likes"."liker_id" = $1 LIMIT $2 [["liker_id", 1], ["LIMIT", 11]]
=> #<ActiveRecord::Associations::CollectionProxy []>
As per the description mentioned in the post you are trying to find the users which have liked my post and the users whom I have liked.
Below mentioned code does not tell rails that likes and likeds are actually users.
has_many :user_likes
has_many :likes, through: :user_likes, foreign_key: :user_liked_id
has_many :likeds, through: :user_likes, foreign_key: :user_liker_id
Modify it to below
has_many :user_likes
has_many :likes, through: :user_likes, foreign_key: :user_liked_id, source: :liked
has_many :likeds, through: :user_likes, foreign_key: :user_liker_id, source: :liked
Best Approach is specifying class along with class name so that rails know in which class is mapped to this foreign key when specifying customized relation names
When your association name is different than the name used at the :through you have to define the source parameter. If you look at the exception message it explicitly asks you to do it.
Hope it answers the question.
Users can follow other Users through FollowingRelationship
I would like to be able to say
User.first.followings and it returns a list of Users
This is not working:
Class User
has_many :following_relationships
has_many :followings, through: :following_relationships, foreign_key: :following_id, source: :user
end
Class FollowingRelationship
attr_accessible :following_id, :follower_id
belongs_to :followings, class_name: "User"
end
User.first.followings gives this in console:
SELECT "users".* FROM "users" INNER JOIN "following_relationships" ON "users"."id" = "following_relationships"."user_id" WHERE "following_relationships"."user_id" = 1
ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column: following_relationships.user_id: SELECT "users".* FROM "users" INNER JOIN "following_relationships" ON "users"."id" = "following_relationships"."user_id" WHERE "following_relationships"."user_id" = 1
Anyone see what piece I am missing?
I think the problem is that FollowingRelationship model doesn't have any relation with User.
It should have belongs_to :user since you specify source: :user, shouldn't it?
I don't quite understand your models and relations between them but belongs_to :followings looks rather strange.
belongs_to uses singular form since it can't belong to more than one object.
UPDATE 1
To be more clear.
I think you should have
class FollowingRelationship
…
belongs_to :user
belongs_to :follower
end
That means followings_relationships table should have user_id and follower_id columns.
UPDATE 2
After some conversation we have figured it out.
Here is the code you should have
class User < ActiveRecord::Base
has_many :fade_relationships, foreign_key: :faded_id
has_many :fadings, through: :fade_relationships, source: :fading
end
class FadeRelationship < ActiveRecord::Base
attr_accessible :faded_id, :fading_id
belongs_to :fading, class_name: "User"
end
I just have found a strange behavior of Active Record, where I am not sure if I am the problem or Active Record ;-).
I am using: Rails 4, Ruby 2.0
Here the models:
class User < ActiveRecord::Base
has_many :conversation_participants, dependent: :destroy
has_many :conversations, through: :conversation_participants
end
class ConversationParticipant < ActiveRecord::Base
belongs_to :user
belongs_to :conversation
end
class Conversation < ActiveRecord::Base
has_many :conversation_participants, dependent: :destroy
has_many :participants, through: :conversation_participants, source: :user
end
Pretty straight forward besides the has_many :participants, which refers to user over source:.
Normally, it is possible to call collection_singular_ids on an has_many associated object. Like in this case:
User.find(1).conversation_ids
This works perfectly, I get back an array of conversations ids. But from the other side:
Conversation.find(1).participant_ids
I alway getting back nil. When I go back to the standard for the has_many:
class Conversation < ActiveRecord::Base
has_many :conversation_participants, dependent: :destroy
has_many :users, through: :conversation_participants
end
Conversation.find(1).user_ids
will work fine.
When I look into the resulting queries, I see what the reason could be:
has_many :users creates:
SELECT "users".id FROM "users" INNER JOIN "conversation_participants" ON "users"."id" = "conversation_participants"."user_id" WHERE "conversation_participants"."conversation_id" = $1 [["conversation_id", 29]]
has_many :participants creates:
SELECT "users".* FROM "users" INNER JOIN "conversation_participants" ON "users"."id" = "conversation_participants"."user_id" WHERE "conversation_participants"."conversation_id" = $1 [["conversation_id", 29]]
in the participants case I get a SELECT "users".* instead SELECT "users".id
(using class_name: "User" has also not helped)
Bug or human error?
Ok, check this weirdness out. I have two types of users, leaders and followers (who each have their own subclasses for reasons that please for the love of god I don't want to go into and moreover are not germaine to this discussion).
class Admin < Account
has_many :leader_follower_relationships, foreign_key: :leader_id, dependent: :destroy
has_many :followers, through: :leader_follower_relationships
end
class Follower < Account
has_one :follower_leader_relationship, class_name: "LeaderfollwerRelationship",
dependent: :destroy
has_one :leader, through: :follower_leader_relationship
end
class LeaderFollowerRelationship < ActiveRecord::Base
belongs_to :follower, class_name: "Follower", foreign_key: :artist_id
belongs_to :leader, class_name: "Admin", foreign_key: :leader_id
end
Anyway, I can establish the relationship using a has_one, but I can't update it:
follower1.leader = leader1
(0.3ms) BEGIN
Account Exists (1.1ms) SELECT 1 AS one FROM "accounts" WHERE "accounts"."auth_token" IS NULL LIMIT 1
Account Exists (0.4ms) SELECT 1 AS one FROM "accounts" WHERE "accounts"."email_address" = 'leader1#example.com' LIMIT 1
SQL (0.6ms) ...
(0.5ms) COMMIT
follower1.leader = leader2
(0.3ms) BEGIN
(1.8ms) UPDATE "leader_follower_relationships" SET "leader_id" = 3 WHERE "leader_follower_relationships"."" IS NULL
(0.2ms) ROLLBACK
ActiveRecord::StatementInvalid: PGError: ERROR: zero-length delimited identifier at or near """"
LINE 1: ...ader_id" = 3 WHERE "leader_follower_relationships"."" IS NULL
If my follower can have many leaders (using has_many), I can both create and update:
class Follower < Account
has_many :follower_leader_relationships, class_name: "LeaderfollwerRelationship",
dependent: :destroy
has_many :leaders, through: :follower_leader_relationships
end
These commands work in succession:
follower1.leaders = [leader1]
follower1.leaders = [leader2]
The ActiveRecord error makes me think that the table for your LeaderFollowerRelationship model does not have an id column. If that's not it, can you post the related bits of schema.rb?