Question

我有两种模式：

class Settlement < ActiveRecord::Base
 set_primary_key :settlement_identifier
 has_many :streets
 attr_accessible :city, :name, :service_available, :zip, :country_id,:  settlement_identifier

end

class Street < ActiveRecord::Base
 belongs_to :settlement, foreign_key: "settlement_identifier"
 attr_accessible :name, :settlement_identifier, :street_identifier
end

因为我正在为街道和定居点进口，我需要通过settlement_identifier指向街道，而不是settlement_id。当我做的时候

Street.first.settlement #it compare settlement_identifiers from both tables

但是当试图从单一定居点获得街道时：

Settlement.first.streets

它会抛出错误

SELECT "streets".* FROM "streets" WHERE "streets"."settlement_id" = 4263

ActiveRecord::StatementInvalid: PG::Error: ERROR:  column streets.settlement_id does not exist .

我希望该查询为：

SELECT "streets".* FROM "streets" WHERE "streets"."settlement_identifier" = 4263

任何帮助？

Answer 1

我解决了这个问题。以下是解决方案：

 class CreateSettlements < ActiveRecord::Migration
  def change
   create_table :settlements, primary_key: :settlement_identifier, id: :false do |t|
    t.string :name
    t.string :zip
    t.string :city
    t.string :service_available
    t.integer :country_id

    t.timestamps
   end
  end
 def down
  drop_table :settlements
 end
end

这里我在迁移到settlement_identifier时设置了primary_key，并将id设置为false

此外，我的街道迁移是：

class CreateStreets < ActiveRecord::Migration
 def change
  create_table :streets do |t|
   t.string :name
   t.integer :settlement_identifier
   t.string :street_identifier
   t.timestamps
  end
 end
end

因此，Street通过settlement_identifier引用了Settlement。

结算模式：

class Settlement < ActiveRecord::Base
 has_many :streets, foreign_key: "settlement_identifier"

 attr_accessible :city, :name, :service_available,:settlement_identifier
end

街头模特：

 class Street < ActiveRecord::Base
  belongs_to :settlement, foreign_key: "settlement_identifier"

  attr_accessible :name, :settlement_identifier, :street_identifier

 end

我尝试在Settlement模型上设置primary_key，但这不起作用。这对我来说很好。如果有人有其他解决方案，请提出评论或代码示例。

在ActiveRecord中更改主键和外键

1 个答案: