验证许多的独特性在Rails的一对多关联 [英] Validate uniqueness of many to many association in Rails

问题描述

说我有项目，那就是在许多-to-many关联是标签即可。我使用的是*的has_many通过*所以我就单独的连接模式。

Say I have Project, that is in many-to-many association with Tag. I'm using *has_many through* so I have separate join model.

如何创建验证，来检查的独特加盟模式？现在，我只有

How do I create validation, that checks uniqueness of join model? Now I have only

has_many :tags, :through => :taggings, :uniq => true

但是，这并不确认保存。

But that doesn't validate on save.

推荐答案

尝试的 validates_associated 。

这是应该的，我相信，允许加入模型验证，在保存之前运行。所以，你的情况：

That should, I believe, allow the join model validations to run before saving. So in your case:

class Project
   has many :tags, :through => :taggings
   validates_associated :taggings
end

class Taggings
   belongs_to :tags

   #your validations here....
end

class Tag
   has_many :taggings
end

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