\"User\" 类型的字段 \"me\" 必须选择子字段

IT技术 javascript graphql graphql-js
2021-03-15 20:53:51

嗨,我正在努力学习GraphQL语言。我有下面的代码片段。

// Welcome to Launchpad!
// Log in to edit and save pads, run queries in GraphiQL on the right.
// Click "Download" above to get a zip with a standalone Node.js server.
// See docs and examples at https://github.com/apollographql/awesome-launchpad

// graphql-tools combines a schema string with resolvers.
import { makeExecutableSchema } from 'graphql-tools';

// Construct a schema, using GraphQL schema language
const typeDefs = `
    type User {
        name: String!
        age: Int!
    }

    type Query {
        me: User
    }
`;

const user = { name: 'Williams', age: 26};

// Provide resolver functions for your schema fields
const resolvers = {
  Query: {
    me: (root, args, context) => {
      return user;
    },
  },
};

// Required: Export the GraphQL.js schema object as "schema"
export const schema = makeExecutableSchema({
  typeDefs,
  resolvers,
});

// Optional: Export a function to get context from the request. It accepts two
// parameters - headers (lowercased http headers) and secrets (secrets defined
// in secrets section). It must return an object (or a promise resolving to it).
export function context(headers, secrets) {
  return {
    headers,
    secrets,
  };
};

// Optional: Export a root value to be passed during execution
// export const rootValue = {};

// Optional: Export a root function, that returns root to be passed
// during execution, accepting headers and secrets. It can return a
// promise. rootFunction takes precedence over rootValue.
// export function rootFunction(headers, secrets) {
//   return {
//     headers,
//     secrets,
//   };
// };

要求:

{
  me
}

回复:

{
  "errors": [
    {
      "message": "Field \"me\" of type \"User\" must have a selection of subfields. Did you mean \"me { ... }\"?",
      "locations": [
        {
          "line": 4,
          "column": 3
        }
      ]
    }
  ]
}

有谁知道我做错了什么?如何解决?

1个回答

从文档

GraphQL 对象类型具有名称和字段,但在某些时候,这些字段必须解析为某些具体数据。这就是标量类型的用武之地:它们代表查询的叶子。

GraphQL 要求您以仅返回具体数据的方式构建查询每个字段最终都必须解析为一个或多个标量(或枚举)。这意味着您不能只请求一个解析为某个类型的字段,而不能同时指明您想要返回该类型的哪些字段。

这就是您收到的错误消息告诉您的内容——您请求了一种User类型,但您没有告诉 GraphQL 至少一个字段以从该类型中返回。

要修复它,只需更改您的请求以包含name如下内容:

{
  me {
    name
  }
}

... 或age. 或两者。但是,您不能请求特定类型并期望 GraphQL 为其提供所有字段——您将始终必须为该类型提供一个选择(一个或多个)字段。