让工厂内的两个关联共享另一个关联

Question

我有这 5 个模型：监护人、学生、关系、关系类型和学校。在它们之间，我有这些关联

class Guardian < ActiveRecord::Base
  belongs_to :school
  has_many :relationships, :dependent => :destroy
  has_many :students, :through => :relationships
end

class Student < ActiveRecord::Base
  belongs_to :school
  has_many :relationships, :dependent => :destroy
  has_many :guardians, :through => :relationships
end

class Relationship < ActiveRecord::Base
  belongs_to :student
  belongs_to :guardian
  belongs_to :relationship_type
end

class School < ActiveRecord::Base
  has_many :guardians, :dependent => :destroy
  has_many :students, :dependent => :destroy
end

class RelationshipType < ActiveRecord::Base
  has_many :relationships
end

，我想编写一个定义关系的 FactoryGirl 。每段关系都必须有监护人和学生。这两个人必须属于同一所学校。监护人工厂与学校有关联，学生工厂也有关联。我一直无法让它们建在同一所学校。我有以下代码：

FactoryGirl.define do

  factory :relationship do
    association :guardian
    association :student, :school => self.guardian.school
    relationship_type RelationshipType.first
  end

end

当我尝试使用此工厂建立关系时，会导致以下错误：

undefined method `school' for #<FactoryGirl::Declaration::Implicit:0x0000010098af98> (NoMethodError)

有没有办法做我想做的事，使监护人和学生属于同一所学校，而不必诉诸于将已经创建的监护人和学生传递到工厂（这不是其目的）？

Answer 1

这个答案是 Google 上关于“工厂女孩共享关联”的第一个结果，来自 santuxus 的答案确实帮助了我:)

这是最新版本的工厂女孩​​的语法更新，以防其他人偶然发现它：

FactoryGirl.define do
  factory :relationship do
    guardian
    relationship_type RelationshipType.first

    after(:build) do |relationship|
      relationship.student = FactoryGirl.create(:student, school: relationship.guardian.school) unless relationship.student.present?
    end
  end
end

unless 子句会阻止 student 在使用 FactoryGirl.create(:relationship, Student: foo) 传递到工厂时被替换。

Answer 2

我认为这应该有效：

FactoryGirl.define do
  factory :relationship do 
    association :guardian
    relationship_type RelationshipType.first
    after_build do |relationship|
      relationship.student = Factory(:student, :school => relationship.guardian.school)
    end
  end
end

Answer 3

有更清晰的方式来编写这个关联。答案来自此 github 问题。

FactoryGirl.define do
  factory :relationship do 
    association :guardian
    student { build(:student, school: relationship.guardian.school) }
    relationship_type RelationshipType.first
  end
end

Answer 4

扩展 nitsas 的解决方案，您可以滥用 @overrides 来检查监护人或学生协会是否已被覆盖，并使用监护人/学生的学校协会。这使您不仅可以凌驾于学校之上，还可以凌驾于监护人或学生之上。

不幸的是，这依赖于实例变量，而不是公共 API。未来的更新很可能会破坏你的工厂。

factory :relationship do
  guardian { create(:guardian, school: school) }
  student  { create(:student,  school: school) }

  transient do
    school do
      if @overrides.key?(:guardian)
        guardian.school
      elsif @overrides.key?(:student)
        student.school
      else
        create(:school)
      end
    end
  end
end

Answer 5

这并不是您真正正在寻求的答案，但似乎创建此关联的困难表明表格设计可能需要调整。

提出问题如果用户改变学校怎么办？，Student 和 Guardian 上的学校都需要更新，否则模型会得到不同步。

我提出学生、监护人、学校三者是一体的。如果学生更换学校，则会为新学校创建新的关系。作为一个很好的副作用，这使得学生所受教育的历史记录得以存在。

belongs_to 关联将从 Student 和 Guardian 中删除，并移至 Relationship。

然后可以将工厂更改为如下所示：

factory :relationship do
  school
  student
  guardian
  relationship_type
end

然后可以通过以下方式使用它：

# use the default relationship which creates the default associations
relationship = Factory.create :relationship
school = relationship.school
student = relationship.student
guardian = relationship.guardian

# create a relationship with a guardian that has two charges at the same school
school = Factory.create :school, name: 'Custom school'
guardian = Factory.create :guardian
relation1 = Factory.create :relationship, school: school, guardian: guardian
relation2 = Factory.create :relationship, school: school, guardian: guardian
student1 = relation1.student
student2 = relation2.student

Answer 6

我会使用 transient &在这种情况下，依赖属性：

FactoryGirl.define do
  factory :relationship do
    transient do
      school { create(:school) }
      # now you can even override the school if you want!
    end

    guardian { create(:guardian, school: school) }
    student { create(:student, school: school) }
    relationship_type RelationshipType.first
  end
end

用法：

relationship = FactoryGirl.create(:relationship)

relationship.guardian.school == relationship.student.school
# => true

而你如果您愿意，甚至可以覆盖学校：

awesome_school = FactoryGirl.create(:school)
awesome_relationship = FactoryGirl.create(:relationship, school: awesome_school)

awesome_relationship.guardian.school == awesome_school
# => true
awesome_relationship.student.school == awesome_school
# => true