dry-struct 如何有条件地验证一个属性？

Question

我正在使用干类型和干结构，我想进行条件验证。

班级：

class Tax < Dry::Struct
  attribute :tax_type, Types::String.constrained(min_size: 2, max_size: 3, included_in: %w[IVA IS NS])
  attribute :tax_country_region, Types::String.constrained(max_size: 5)
  attribute :tax_code, Types::String.constrained(max_size: 10)
  attribute :description, Types::String.constrained(max_size: 255)
  attribute :tax_percentage, Types::Integer
  attribute :tax_ammount, Types::Integer.optional
end

我想将tax_ammount 验证为整数和强制if `tax_type == 'IS'。

Answer 1

dry-struct 真正用于基本类型断言和强制。

如果您想要更复杂的验证，那么您可能还想实现dry-validation（正如dry-rb 推荐的那样）

查看Validating data with dry-struct 哪些状态

请不要。结构体旨在与有效输入一起工作，它无法生成足以向用户显示它们的错误消息等。使用干验证来验证传入数据，然后将其输出传递给结构体。

使用dry-validation 的条件验证类似于

TaxValidation = Dry::Validation.Schema do

  # Could be:
  #   required(:tax_type).filled(:str?, 
  #      size?: 2..3, 
  #      included_in?: %w(IVA IS NS)) 
  # but since we are validating against a list of Strings I figured the rest was implied
  required(:tax_type).filled(included_in?: %w(IVA IS NS)) 
  optional(:tax_amount).maybe(:int?)

  # rule name is of your choosing and will be used 
  # as the errors key (i just chose `tax_amount` for consistency)
  rule(tax_amount:[:tax_type, :tax_amount]) do |tax_type, tax_amount|
    tax_type.eql?('IS').then(tax_amount.filled?) 
  end
end

• 这要求tax_type 在%w(IVA IS NS) 列表中；
• 允许tax_amount 是可选的，但如果填写它必须是Integer (int?) 和；
• 如果tax_type == 'IS' (eql?('IS')) 则必须填写tax_amount（这意味着根据上述规则，它必须是Integer）。

显然，您也可以验证您的其他输入，但为了简洁起见，我省略了这些。

例子：

TaxValidation.({}).success?
#=> false
TaxValidation.({}).errors
# => {:tax_type=>["is missing"]}
TaxValidation.({tax_type: 'NO'}).errors
#=>  {:tax_type=>["must be one of: IVA, IS, NS"]}
TaxValidation.({tax_type: 'NS'}).errors
#=>  {}
TaxValidation.({tax_type: 'IS'}).errors
#=> {:tax_amount=>["must be filled"]}
TaxValidation.({tax_type: 'IS',tax_amount:'NO'}).errors
#=> {:tax_amount=>["must be an integer"]}
TaxValidation.({tax_type: 'NS',tax_amount:12}).errors 
#=> {}
TaxValidation.({tax_type: 'NS',tax_amount:12}).success?
#=> true