这是一个完整的工作示例:
迁移文件:
class CreateUserEntities < ActiveRecord::Migration
def change
create_table :user_entities do |t|
t.integer :user_id
t.references :entity, polymorphic: true
t.timestamps
end
add_index :user_entities, [:user_id, :entity_id, :entity_type]
end
end
型号:
class User < ActiveRecord::Base
has_one :user_entity
has_one :client, through: :user_entity, source: :entity, source_type: 'Client'
has_one :agency, through: :user_entity, source: :entity, source_type: 'Agency'
def entity
self.user_entity.try(:entity)
end
def entity=(newEntity)
self.build_user_entity(entity: newEntity)
end
end
class UserEntity < ActiveRecord::Base
belongs_to :user
belongs_to :entity, polymorphic: true
validates_uniqueness_of :user
end
class Client < ActiveRecord::Base
has_many :user_entities, as: :entity
has_many :users, through: :user_entities
end
class Agency < ActiveRecord::Base
has_many :user_entities, as: :entity
has_many :users, through: :user_entities
end
如您所见,我添加了一个 getter 和一个 setter,我将其命名为“实体”。这是因为has_one :entity, through: :user_entity
引发以下错误:
ActiveRecord::HasManyThroughAssociationPolymorphicSourceError: Cannot have a has_many :through association 'User#entity' on the polymorphic object 'Entity#entity' without 'source_type'. Try adding 'source_type: "Entity"' to 'has_many :through' definition.
最后,这是我设置的测试。我给它们是为了让每个人都明白知道你可以在这些对象之间设置和访问数据。我不会详细介绍我的 FactoryGirl 模型,但它们非常明显
require 'test_helper'
class UserEntityTest < ActiveSupport::TestCase
test "access entity from user" do
usr = FactoryGirl.create(:user_with_client)
assert_instance_of client, usr.user_entity.entity
assert_instance_of client, usr.entity
assert_instance_of client, usr.client
end
test "only right entity is set" do
usr = FactoryGirl.create(:user_with_client)
assert_instance_of client, usr.client
assert_nil usr.agency
end
test "add entity to user using the blind rails method" do
usr = FactoryGirl.create(:user)
client = FactoryGirl.create(:client)
usr.build_user_entity(entity: client)
usr.save!
result = UserEntity.where(user_id: usr.id)
assert_equal 1, result.size
assert_equal client.id, result.first.entity_id
end
test "add entity to user using setter" do
usr = FactoryGirl.create(:user)
client = FactoryGirl.create(:client)
usr.client = client
usr.save!
result = UserEntity.where(user_id: usr.id)
assert_equal 1, result.size
assert_equal client.id, result.first.entity_id
end
test "add entity to user using blind setter" do
usr = FactoryGirl.create(:user)
client = FactoryGirl.create(:client)
usr.entity = client
usr.save!
result = UserEntity.where(user_id: usr.id)
assert_equal 1, result.size
assert_equal client.id, result.first.entity_id
end
test "add user to entity" do
usr = FactoryGirl.create(:user)
client = FactoryGirl.create(:client)
client.users << usr
result = UserEntity.where(entity_id: client.id, entity_type: 'client')
assert_equal 1, result.size
assert_equal usr.id, result.first.user_id
end
test "only one entity by user" do
usr = FactoryGirl.create(:user)
client = FactoryGirl.create(:client)
agency = FactoryGirl.create(:agency)
usr.agency = agency
usr.client = client
usr.save!
result = UserEntity.where(user_id: usr.id)
assert_equal 1, result.size
assert_equal client.id, result.first.entity_id
end
test "user uniqueness" do
usr = FactoryGirl.create(:user)
client = FactoryGirl.create(:client)
agency = FactoryGirl.create(:agency)
UserEntity.create!(user: usr, entity: client)
assert_raise(ActiveRecord::RecordInvalid) {
UserEntity.create!(user: usr, entity: agency)
}
end
end
我希望这可以对某人有所帮助。我决定将整个解决方案放在这里,因为与 MTI 相比,它在我看来是一个不错的解决方案,而且我认为设置类似的东西不应该花费太多时间。