Rails 3:嵌套fields_for的唯一性验证

Question

A有两个型号,"商店"和"产品",通过has_many:through链接.

在商店表单中有多个产品的嵌套属性,我在产品的唯一性验证方面遇到了一些麻烦.如果我输入产品,保存它,然后尝试为新产品输入相同的名称,则唯一性验证会成功触发.

但是,如果我在同一嵌套表单的两行中输入相同的产品名称,则表单被接受 - 唯一性验证不会触发.

我猜这是一个相当普遍的问题,但我找不到任何简单的解决方案.任何人都有最简单的方法建议,以确保在同一嵌套表格中遵守唯一性验证？

编辑:下面包含的产品型号

class Product < ActiveRecord::Base

  has_many :shop_products
  has_many :shops, :through => :shop_products

  validates_presence_of :name
  validates_uniqueness_of :name
end

Answer 1

为了扩展Alberto的解决方案,以下自定义验证器接受要验证的字段(属性),并向嵌套资源添加错误.

# config/initializers/nested_attributes_uniqueness_validator.rb
class NestedAttributesUniquenessValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value)
    unless value.map(&options[:field]).uniq.size == value.size
      record.errors[attribute] << "must be unique"
      duplicates = value - Hash[value.map{|obj| [obj[options[:field]], obj]}].values
      duplicates.each { |obj| obj.errors[options[:field]] << "has already been taken" }
    end
  end
end

# app/models/shop.rb
class Shop < ActiveRecord::Base
  validates :products, :nested_attributes_uniqueness => {:field => :name}
end

Answer 2

你可以编写一个自定义验证器

# app/validators/products_name_uniqueness_validator.rb
class ProductsNameUniquenessValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value)
    record.errors[attribute] << "Products names must be unique" unless value.map(&:name).uniq.size == value.size
  end
end

# app/models/shop.rb
class Shop < ActiveRecord::Base
  validates :products, :products_name_uniqueness => true
end