Rails:验证两列的唯一性(一起)

问题描述

我有一个带有 medium 和 country 列(以及其他)的 Release 模型.不应有共享相同的 medium/country 组合的 releases.

I have a Release model with medium and country columns (among others). There should not be releases that share identical medium/country combinations.

我将如何将其编写为 Rails 验证?

How would I write this as a rails validation?

推荐答案

您可以使用 uniqueness 使用 scope 选项进行验证.

You can use a uniqueness validation with the scope option.

此外，您应该向数据库添加唯一索引，以防止新记录在写入前同时检查时通过验证:

Also, you should add a unique index to the DB to prevent new records from passing the validations when checked at the same time before being written:

class AddUniqueIndexToReleases < ActiveRecord::Migration
  def change
    add_index :releases, [:country, :medium], unique: true
  end
end



class Release < ActiveRecord::Base
  validates :country, uniqueness: { scope: :medium }
end

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