Graphql Typecheck on redux like events

Question

我正在使用 apollo-server 在一些现有的 REST api 上实现一个 graphql 服务器。

有一个端点返回一个类似 redux 的事件列表，其中 Hi 有一个 type 和一个 payload。 type 是一个字符串，payload 是一个对象。例如

[
   {
      type:"joined"
      from:"member1"
      payload:{
        received_events:"1518377870416"
        invited_by:"member2"
      }    
   },   
   {
      type:"text"
      from:"member1"
      payload:{
        test_string:"hello"
      }    
   }
 ]

我需要检查的是：

1) type 是枚举 joined|text

2) from 是一个字符串

3) if type == joined then payload should contain received_events and invited_by, if type == text then payload should contain test_string

最好的方法是什么？我正在查看 scalar 和 Union，但我不确定该怎么做。

Answer 1

解决此问题的一种方法是将事件类型中的类型注入到有效负载对象中。然后可以在联合的 __resolveType 解析器中使用它。一个简单的例子：

const typeDefs = `
  type Query {
    events: [Event]
  }
  type Event {
    type: String
    payload: Payload
  }
  union Payload = Text | Joined
  type Text {
    test_string: String
  }
  type Joined {
    received_events: String
    invited_by: String
  }
`;

// Since your type names and the specified types are different, we
// need to map them (resolveType needs to return the exact name)
const typesMap = {
  text: 'Text',
  joined: 'Joined'
}

const resolvers = {
  Query: {
    events: (root, args, context) => {
      return [
        { type: 'text', payload: { test_string: 'Foo' } }
      ];
    },
  },
  // We can use the resolver for the payload field to inject the type
  // from the parent object into the payload object
  Event: {
    payload: (obj) => Object.assign({ type: obj.type }, obj.payload)
  },
  // The type can then be referenced inside resolveType
  Payload: {
    __resolveType: (obj) => typesMap[obj.type]
  }
};

Graphql Typecheck on redux like events

Graphql Typecheck on redux like events

graphql

graphql-js

apollo-server