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我有一个包含 3 个模型的应用程序：租户、部门、标准。

# app/models/department.rb

class Department < ActiveRecord::Base
  attr_accessible :name, :abbr

  has_many :renter_departments
  has_many :renters, :through => :renter_departments
end

和

# app/models/criterium.rb

class Criterium < ActiveRecord::Base
  attr_accessible :name

  has_many :renter_criteria
  has_many :renters, :through => :renter_criteria
end

我正在尝试在 Renter 模型中创建两个范围，让我可以按部门和标准找到租户。

这是我的代码：

# app/models/renter.rb

class Renter < ActiveRecord::Base

  # Relationships
  has_many :renter_departments
  has_many :renter_criteria
  has_many :departments, :through => :renter_departments
  has_many :criteria, :through => :renter_criteria

  # Scopes
  scope :from_department, lambda { |abbr| joins(:departments).where("abbr = ?", abbr) }
  scope :has_criterium, lambda { |criterium| joins(:criteria).where("name = ?", criterium) }

end

使用

Renter.from_department("SCS")

或者

Renter.has_criterium("Economic considerations")

自行工作。但是，当我尝试将它们链接起来时，

Renter.from_department("SCS").has_criterium("Economic considerations")

我收到一条错误消息：

  Renter Load (0.3ms)  SELECT "renters".* FROM "renters" INNER JOIN "renter_departments" ON "renter_departments"."renter_id" = "renters"."id" INNER JOIN "departments" ON "departments"."id" = "renter_departments"."department_id" INNER JOIN "renter_criteria" ON "renter_criteria"."renter_id" = "renters"."id" INNER JOIN "criteria" ON "criteria"."id" = "renter_criteria"."criterium_id" WHERE (abbr = 'SCS') AND (name = 'Economic considerations')
SQLite3::SQLException: ambiguous column name: name: SELECT "renters".* FROM "renters" INNER JOIN "renter_departments" ON "renter_departments"."renter_id" = "renters"."id" INNER JOIN "departments" ON "departments"."id" = "renter_departments"."department_id" INNER JOIN "renter_criteria" ON "renter_criteria"."renter_id" = "renters"."id" INNER JOIN "criteria" ON "criteria"."id" = "renter_criteria"."criterium_id" WHERE (abbr = 'SCS') AND (name = 'Economic considerations')
ActiveRecord::StatementInvalid: SQLite3::SQLException: ambiguous column name: name: SELECT "renters".* FROM "renters" INNER JOIN "renter_departments" ON "renter_departments"."renter_id" = "renters"."id" INNER JOIN "departments" ON "departments"."id" = "renter_departments"."department_id" INNER JOIN "renter_criteria" ON "renter_criteria"."renter_id" = "renters"."id" INNER JOIN "criteria" ON "criteria"."id" = "renter_criteria"."criterium_id" WHERE (abbr = 'SCS') AND (name = 'Economic considerations')

此外，

>> Renter.from_department("SCS").class
=> ActiveRecord::Relation
>> Renter.has_criterium("Economic considerations").class
=> ActiveRecord::Relation

关于我做错了什么的任何想法？

4

2 回答 2

2

您要加入的表中有多个name列。使WHERE子句使用renters.nameordepartments.name或具有适当name列的任何表。

于 2012-05-01T00:01:39.963 回答
1

您需要在范围内引用表名：

scope :from_department, lambda { |abbr| joins(:departments).where("departments.abbr = ?", abbr) }
scope :has_criterium, lambda { |criterium| joins(:criteria).where("criteria.name = ?", criterium) }
于 2012-05-01T00:10:17.950 回答