导轨 - 验证presence协会？

问题描述

我有，有一个的has_many的关联关系模型B.我有一个插入到至少需要1相关的记录B.业务需求模型中的是否有一种方法，我可以打电话，以确保这是真实的，或者我需要编写一个自定义的验证？

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 <一个href="http://apidock.com/rails/ActiveModel/Validations/ClassMethods/validates_$p$psence_of">http://apidock.com/rails/ActiveModel/Validations/ClassMethods/validates_$p$psence_of

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

或只是只会验证http://apidock.com/rails/ActiveModel/Validations/ClassMethods/validates

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

但有与它的错误，如果你会使用 accepts_nested_attributes_for 与：allow_destroy =＆GT;真正的：嵌套模型和家长的验证。在这个主题中，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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