Rails GraphQL Mutations如何根据其他参数动态设置字段required必填属性

实现方案说明 #

GraphQL 本身的类型校验逻辑是静态执行的，在接口声明阶段就已经确定了所有参数的必填规则，无法直接通过给required属性传proc的方式实现依赖其他参数的动态必填校验，你示例中的写法原生 GraphQL Ruby 并不支持，可通过以下两种成熟方案实现需求：

方案1：参数声明为非必填，在resolve方法内做自定义校验 #

这是最常用的实现方式，修改后代码如下：

class Mutations::CreateAuthor < Mutations::BaseMutation
  description "Creates Author"

  argument :name, String, required: false
  # 原声明的必填改为非必填，移到业务逻辑内校验
  argument :email, String, required: false
  argument :phone, String, required: false

  field :author, Types::AuthorType, null: false
  field :errors, [String], null: false

  def resolve(name:, email:, phone:)
    # 自定义参数校验逻辑
    errors = []
    if email.blank? && phone.blank?
      errors << "邮箱和手机号不能同时为空，至少填写一项"
    end
    return {author: nil, errors: errors} if errors.present?

    author = Author.new(name: name, email: email, phone: phone)
    if author.save
      {author: author, errors: []}
    else
      {author: nil, errors: author.errors.full_messages}
    end
  end
end

方案2：用ready?回调做前置校验 #

如果不想把校验逻辑耦合到resolve方法里，可以用 Mutation 自带的ready?回调在执行业务逻辑前完成参数校验：

class Mutations::CreateAuthor < Mutations::BaseMutation
  description "Creates Author"

  argument :name, String, required: false
  argument :email, String, required: false
  argument :phone, String, required: false

  field :author, Types::AuthorType, null: false
  field :errors, [String], null: false

  def ready?(**args)
    if args[:email].blank? && args[:phone].blank?
      raise GraphQL::ExecutionError, "邮箱和手机号不能同时为空，至少填写一项"
    end
    true
  end

  def resolve(name:, email:, phone:)
    author = Author.new(name: name, email: email, phone: phone)
    if author.save
      {author: author, errors: []}
    else
      {author: nil, errors: author.errors.full_messages}
    end
  end
end

如果你希望这个动态必填规则能体现在接口文档中，可以在字段描述里明确标注「邮箱、手机号至少填写一项」的规则，方便前端调用方提前知晓校验逻辑。

内容的提问来源于stack exchange，提问作者Hammad Qadeer