Ruby-on-rails 如何建立一对多的关系？
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How to setup a one to many relationship?
提问by AnApprentice
I have the following models:
我有以下型号：
User (id, name, network_id)
Network(id, title)
What kind of Rails model assoc do I need to add so that I can do:
我需要添加什么样的 Rails 模型 assoc 以便我可以：
@user.network.title
@network.users
Thanks
谢谢
回答by daniel
so network has_manyusers and a user belongs_tonetwork.
所以网络has_many用户和用户belongs_to网络。
Just add a network_idto users table if you still haven't and also since it's a foreign_keyis worth indexing it.
network_id如果您还没有，只需将 a 添加到 users 表，并且因为它foreign_key值得对其进行索引。
rails generate migration AddNetworkIdToUsers
rails generate migration AddNetworkIdToUsers
class AddNetworkIdToUsers < ActiveRecord::Migration
def change
add_column :users, :network_id, :integer
add_index :users, :network_id
end
end
In the network model do:
在网络模型中：
class Network < ActiveRecord::Base
has_many :users
end
In the user model do:
在用户模型中：
class User < ActiveRecord::Base
belongs_to :network
end
回答by klaffenboeck
According to your database-setup, you just have to add the following lines to your models:
根据您的数据库设置，您只需将以下几行添加到您的模型中：
class User < ActiveRecord::Base
belongs_to :network
# Rest of your code here
end
class Network < ActiveRecord::Base
has_many :users
# Rest of your code here
end
In case you have a setup without network_id, you should go with daniels answer.
如果您的设置没有 network_id，您应该使用 daniels 的答案。
回答by hula-san
This is my way: run:
这是我的方式：运行：
$rails generate migration AddNetworkIdToUsers
then config migration file:
然后配置迁移文件：
class AddNetworkIdToUsers < ActiveRecord::Migration[5.1]
def up
add_column :users, :network_id, :integer
add_index :users, :network_id
end
def down
remove_index :users, :network_id
remove_column :users, :network_id
end
end
