rails has_many 最小集合大小更新验证 [英] rails has_many minimum collection size update validation

问题描述

我有一个接受嵌套属性的 has_many 关联.我需要集合中至少有 1 个关联对象，因此我编写了一个自定义验证器:

I have a has_many association that accepts nested attributes. I need for there to be a minimum of 1 associated object in the collection, so I wrote a custom validator:

class MinimumCollectionSizeValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value)
    if value.size < options[:size]
      record.errors[attribute] << (options[:message] || "must have at least #{options[:size]} line.")
    end
  end
end

模型看起来像:

has_many :foos, :dependent=>:destroy
accepts_nested_attributes_for :foos
validates :foos, :minimum_collection_size=>{:size=>1}

这在模型创建上效果很好，但在更新时失败了.@my_model.update_attributes(params[:my_model]) 返回 true，即使 _destroy 删除了所有 foos.

This works great on model creation, but fails miserable on update. @my_model.update_attributes(params[:my_model]) returns true even if all the foos are removed by _destroy.

如何让 update_attributes 的行为与 save 相同?

How do I get update_attributes to behave the same as save?

推荐答案

验证集合最小大小的更好方法:

A better way to validate the minimum size of a collection:

validates :my_association, :length => { :minimum => Fixnum}

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