rails self join
跳到 Self Joins - 2.10 Self Joins. In designing a data model, you will sometimes find a model that should have a relation to itself. For example, you may want ... ,A User can have many: followers in its capacity as followee; followees in its capacity as follower. Here's how the code for user.rb might look: class User ... , You can do a has_many :through through a belongs_to association. For example this will allow you to access a Supervisor 's drivers and chefs ..., Ok so in the end I got it to work with some slight modification. First I renamed some things to make it make a little more sense (if only in my ..., class Transaction < ApplicationRecord has_one :payback_transaction, class_name: 'Transaction', foreign_key: :parent_transaction_id ..., Self Joins. There's a way to create ActiveRecord associations within a single table! It's called a self join. The concept is a little harder than you think to first wrap your head around.,Add a scope to your category, then use it on your parent object: class Category < ActiveRecord::Base belongs_to :parent, :class_name => "Category" has_many ... , Each of these relationships can be set up just two tables: the user table, and a join table to link it to itself. For this example let's create a rails app ..., Self-referential association means we create a JOIN MODEL, such as Friendship, for example, which links another model, such as User to itself, so a user can have many friends (which are other users), and a friend can be befriended by a user ( a follower , I was missing the has_many foreign key to "parent_post_id". Once its set, the post.replies will reference other Post instances by parent_post_id.
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 rails self join 相關參考資料
Active Record Associations — Ruby on Rails Guides
跳到 Self Joins - 2.10 Self Joins. In designing a data model, you will sometimes find a model that should have a relation to itself. For example, you may want ... https://guides.rubyonrails.org Many-to-many self join in rails? - Stack Overflow
A User can have many: followers in its capacity as followee; followees in its capacity as follower. Here's how the code for user.rb might look: class User ... https://stackoverflow.com Ruby On Rails self join associations - Stack Overflow
You can do a has_many :through through a belongs_to association. For example this will allow you to access a Supervisor 's drivers and chefs ... https://stackoverflow.com Ruby on Rails: has_many self join - Stack Overflow
Ok so in the end I got it to work with some slight modification. First I renamed some things to make it make a little more sense (if only in my ... https://stackoverflow.com Self Join on a Table using Ruby on Rails ActiveRecord - Stack ...
class Transaction < ApplicationRecord has_one :payback_transaction, class_name: 'Transaction', foreign_key: :parent_transaction_id ... https://stackoverflow.com Self Joins - Andrew Bonner - Medium
Self Joins. There's a way to create ActiveRecord associations within a single table! It's called a self join. The concept is a little harder than you think to first wrap your head around. https://medium.com Self joins in Ruby on Rails - Stack Overflow
Add a scope to your category, then use it on your parent object: class Category < ActiveRecord::Base belongs_to :parent, :class_name => "Category" has_many ... https://stackoverflow.com Self-Referential Relationships (aka Self-Joins) in Rails - Medium
Each of these relationships can be set up just two tables: the user table, and a join table to link it to itself. For this example let's create a rails app ... https://medium.com The power of Self -Referential Associations in Rails (and self ...
Self-referential association means we create a JOIN MODEL, such as Friendship, for example, which links another model, such as User to itself, so a user can have many friends (which are other users),... https://medium.com Understanding Rails ActiveRecord "single model" self joins ...
I was missing the has_many foreign key to "parent_post_id". Once its set, the post.replies will reference other Post instances by parent_post_id. https://stackoverflow.com |