class Team < ApplicationRecord
end
class Game < ApplicationRecord
belongs_to :winner, class_name: 'Team'
belongs_to :loser, class_name: 'Team'
end
Thanks in advance. Is it possible to write a dependence for destroy a belonged Game instance when a Team instance is destroyed? I didn't find anything on it, all things, I tried, like
class Team < ApplicationRecord
has_many :games, inverse_of: :winner, dependent: :destroy
...
didn't work.
You need to add foreign keys
class Team < ApplicationRecord
has_many :winner_games, foreign_key: :winner_id, class_name: 'Game', dependent: :destroy
has_many :loser_games, foreign_key: :loser_id, class_name: 'Game', dependent: :destroy
end
Related
Wondering about a relationship I have and not sure wheter this is due to cause some issues in the future.
I have the following relationships with Users and Leases.
class User < ApplicationRecord
has_one :lease, foreign_key: "tenant_id"
has_many :leases, foreign_key: "landlord_id"
end
and
class Lease < ApplicationRecord
belongs_to :tenant, class_name: "User"
belongs_to :landlord, class_name: "User"
end
and I'm trying to convert the relationship with the tenant and the lease to has_many, but I don't know how to approach this the right way.
I got this to work with
class User < ApplicationRecord
has_many :leases_as_landlord, class_name: "Lease", foreign_key: "tenant_id"
has_many :leases_as_tenant, class_name: "Lease", foreign_key: "landlord_id"
end
and
class Lease < ApplicationRecord
belongs_to :tenant, class_name: "User", inverse_of: :leases_as_tenant
belongs_to :landlord, class_name: "User", inverse_of: :leases_as_landlord
end
but I don't like calling User.leases_as_landlord and User.leases_as_tenant. What I would like to do is just call User.leases to return the leases in which the User is either the landlord or the tenant.
You can add instance method:
class User < ApplicationRecord
has_many :leases_as_landlord, class_name: "Lease", foreign_key: "tenant_id"
has_many :leases_as_tenant, class_name: "Lease", foreign_key: "landlord_id"
def leases
leases_as_landlord.or(leases_as_tenant)
end
end
It will also return ActiveRecord_AssociationRelation and you can chain other ActiveRecord method on it.
Also I would recommend to follow Rails Convention and name your has_many associations in the plural.
class User < ApplicationRecord
has_many :landlord_leases, class_name: 'Lease', foreign_key: :tenant_id
has_many :tenant_leases, class_name: 'Lease', foreign_key: :landlord_id
def leases
landlord_leases.or(tenant_leases)
end
end
I am a newbie in Rails and have issues with Ransack:
This is model Project
class Project < ApplicationRecord
searchkick
belongs_to :company
belongs_to :m_category
has_many :project_industries, dependent: :destroy
has_many :m_industries, through: :project_industries
end
This is model Industry:
class Industry < ApplicationRecord
include M
belongs_to :m_industry_category
has_many :project_industries, dependent: :destroy, foreign_key: :industry_id
has_many :projects, through: :project_industries
end
And this is model IndustryCategory:
class IndustryCategory < ApplicationRecord
has_many :industries, dependent: :destroy,
foreign_key: :industry_category_id
has_many :projects, through: :industries
end
Now, I want to search the Project by IndustryCategory but I don't know how. please help me!! tks
You can use something like this
#industrty_category = IndustryCategory.find(params[:id])
#project = #industry_category.projects.all
I'm trying to access products through promotion but can't.
In the command line: Promotion.last.promotion_rules.first.products
Returns an error of an uninitialized constant.
Here are my associations:
class Product
has_many :product_promotion_rules, class_name: 'ProductPromotionRule'
has_many :promotion_rules, through: :product_promotion_rules
end
class ProductPromotionRule
belongs_to :product
belongs_to :promotion_rule
end
class PromotionRule
has_many :product_promotion_rules, class_name: 'ProductPromotionRule', join_table: 'products_promotion_rules', foreign_key: :promotion_rule_id
has_many :products, through: :product_promotion_rules
belongs_to :promotion
end
class Promotion
has_many :promotion_rules
end
Within the Product model try:
has_many :product_promotion_rules, class_name: 'ProductPromotionRule', foreign_key: :product_id
has_many :promotion_rules, through: :product_promotion_rules, source: :promotion_rule
And within the PromotionRule model:
has_many :products, through: :product_promotion_rules, source: :product
Update: saw this, which you may want to remove/fix:
join_table: products_promotion_rules
Either change to:
join_table: product_promotion_rules
Or try removing it.
I have 4 Models and i am not sure what is the correct way to write my relationships/associations.
class User < ActiveRecord::Base
has_many :boards
has_many :lists
has_many :cards
end
class Board < ActiveRecord::Base
belongs_to :user
has_many :lists
end
class List < ActiveRecord::Base
belongs_to :user
belongs_to :board
has_many :cards
end
class Card < ActiveRecord::Base
belongs_to :user
belongs_to :list
end
If you want to be more explicit about your relationships, feel free to do the following (preferred in most every case):
class User < ActiveRecord::Base
has_many :boards, inverse_of: :user, dependent: :destroy
has_many :lists, inverse_of: :user, dependent: :destroy
has_many :cards, inverse_of: user, dependent: :destroy
end
class Board < ActiveRecord::Base
belongs_to :user, inverse_of: :boards
has_many :lists, inverse_of: :board
end
class List < ActiveRecord::Base
belongs_to :user, inverse_of: :lists
belongs_to :board, inverse_of :lists
has_many :cards, inverse_of :list
end
class Card < ActiveRecord::Base
belongs_to :user, inverse_of: :cards
belongs_to :list, inverse_of :cards
end
Finally, make sure any of your models that are dependent on another (e.g. Board belongs_to User) have the appropriate foreign key in their table. So, for example, Board will need to have a user_id foreign key to correctly create the association.
You can create a migration for any of those entities if you haven't already like so:
rails generate migration AddUserRefToBoards user:references
I'm trying to create a join table between 2 models that has 3 columns. The models are called User and Dare. The join table is called DaresUsers. And what I want to include in the join table is an author_id, accepter_id, dare_id.
Each dare will only have one author but will have many accepters because more than one user can accept the same dare. Should I use a has_many through relationship and if so what would I declare in my models? My confusion here is because the User model is referenced by the join table in two respects: the author_id and accepter_id.
Thanks for any help!
Try this:
class Dare < ActiveRecord::Base
belongs_to :author, class_name: 'User'
has_many :dare_user_relations, dependent: :destroy
has_many :accepters, through: :dare_user_relations
end
class DareUserRelation < ActiveRecord::Base
belongs_to :accepter, class_name: 'User'
belongs_to :dare
end
class User < ActiveRecord::Base
has_one :dare, foreign_key: 'author_id', dependent: :destroy
has_many :dare_user_relations, dependent: :destroy
has_many :dares, through: :dare_user_relations, foreign_key: 'accepter_id'
end
or w/o a model:
class Dare < ActiveRecord::Base
belongs_to :author, class_name: 'User'
has_and_belongs_to_many :accepters, class_name: 'User', association_foreign_key: 'accepter_id'
end
class User < ActiveRecord::Base
has_one :dare, foreign_key: 'author_id', dependent: :destroy
has_and_belongs_to_many :dares, foreign_key: 'accepter_id'
end