GraphQL服务返回空数据求助：新手学习遇数据返回异常

我是GraphQL新手，学习时遇到问题：我的GraphQL服务本该返回预设数据，但实际返回null。网上找了方案没解决，应该是漏了细节，求帮忙。

相关代码文件 #

index.js #

import { ApolloServer } from "@apollo/server";
import { startStandaloneServer } from "@apollo/server/standalone";
import { typeDefs } from "./schema.js";
import db from "./_db.js";

const resolvers = {
    Query:{
        games(){
            return db.games
        },
        authors(){
            return db.authors
        },
        reviews(){
            return db.reviews
        }
    }
}

//server setup
const server = new ApolloServer({
    //typeDefs -- definition of types of data game
    //resolvers -- functions that are called to get data for each field in a type'

    typeDefs,

})

const {url} = await startStandaloneServer(server, {
    listen: { port: 4000 }
});

console.log("Server ready at port", 4000)

schema.js #

//int, float, string, boolean, ID - 5 basic scalar types

export const typeDefs = `#graphql
    type Game{
        id: ID!
        title: String!
        platform: [String]!
    }

    type Review{
        id: ID!
        rating: Int!
        content: String!
    }

    type Author{
        id: ID!
        name: String!
        verified: Boolean!
    }

    type Query{
        reviews: [Review]
        games: [Game]
        authors: [Author]
    }
`

_db.js #

let games = [
    {id: '1', title: 'Zelda, Tears of the Kingdom', platform: ['Switch']},
    {id: '2', title: 'Final Fantasy 7 Remake', platform: ['PS5', 'Xbox']},
    {id: '3', title: 'Elden Ring', platform: ['PS5', 'Xbox', 'PC']},
    {id: '4', title: 'Mario Kart', platform: ['Switch']},
    {id: '5', title: 'Pokemon Scarlet', platform: ['PS5', 'Xbox', 'PC']},
]

let authors = [
    {id: '1', name: 'mario', verified: true},
    {id: '2', name: 'yoshi', verified: false},
    {id: '3', name: 'peach', verified: true},
]

let reviews = [
    {id: '1', rating: 9, content: 'lorem ipsum', author_id: '1', game_id: '2'},
    {id: '2', rating: 10, content: 'lorem ipsum', author_id: '2', game_id: '1'},
    {id: '3', rating: 7, content: 'lorem ipsum', author_id: '3', game_id: '3'},
    {id: '4', rating: 5, content: 'lorem ipsum', author_id: '2', game_id: '4'},
    {id: '5', rating: 8, content: 'lorem ipsum', author_id: '2', game_id: '5'},
    {id: '6', rating: 7, content: 'lorem ipsum', author_id: '1', game_id: '2'},
    {id: '7', rating: 10, content: 'lorem ipsum', author_id: '3', game_id: '1'},
]
export default { games, authors, reviews }

问题原因及修复 #

创建ApolloServer实例时，未传入resolvers配置。ApolloServer需要同时接收typeDefs和resolvers才能正确处理查询，缺少resolvers的话，服务无法获取数据，就会返回null。

修改index.js里的ApolloServer初始化代码，添加resolvers参数：

const server = new ApolloServer({
    typeDefs,
    resolvers // 新增此行
})

重启服务后再执行查询，即可拿到预设的游戏、作者和评论数据。

内容的提问来源于stack exchange，提问作者e36_King