我想学习GraphQL,并且在文档中有一个启动代码,可在带有express框架的node.js上运行:
var express = require('express');
var graphqlHTTP = require('express-graphql');
var { buildSchema } = require('graphql');
var schema = buildSchema(`
type Query {
hello: String
}
`);
var root = { hello: () => 'Hello world!' };
var app = express();
app.use('/graphql', graphqlHTTP({
schema: schema,
rootValue: root,
graphiql: true,
}));
app.listen(4000, () => console.log('Now browse to localhost:4000/graphql'));
每件事都运行正常,但我不明白这一行:
var { buildSchema } = require('graphql');
为什么有花括号?为了什么?