Rails - 验证关联的存在? [英] Rails - Validate Presence Of Association?

问题描述

我有一个模型 A，它与另一个模型 B 具有has_many"关联.我有一个业务要求，即插入 A 需要至少 1 个与 B 相关联的记录.是否有我可以调用的方法来确保这一点是真的，还是我需要编写自定义验证?

I have a model A that has a "has_many" association to another model B. I have a business requirement that an insert into A requires at least 1 associated record to B. Is there a method I can call to make sure this is true, or do I need to write a custom validation?

推荐答案

您可以使用 validates_presence_of http://apidock.com/rails/ActiveModel/Validations/ClassMethods/validates_presence_of

class A < ActiveRecord::Base
  has_many :bs
  validates_presence_of :bs
end

或者只是validateshttp://apidock.com/rails/ActiveModel/Validations/ClassMethods/validates

class A < ActiveRecord::Base
  has_many :bs
  validates :bs, :presence => true
end

但是，如果您将 accepts_nested_attributes_for 与 :allow_destroy => 一起使用，它会存在一个错误.true:嵌套模型和父验证.在本主题中，您可以找到解决方案.

But there is a bug with it if you will use accepts_nested_attributes_for with :allow_destroy => true: Nested models and parent validation. In this topic you can find solution.

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