express-graphql 使用

var express = require("express");
var express_graphql = require("express-graphql");
var { buildSchema } = require("graphql");
// GraphQL schema
var schema = buildSchema(`
    type Query {
        course(id: Int!): Course
        courses(topic: String): [Course]
    },
    type Course {
        id: Int
        title: String
        author: String
        description: String
        topic: String
        url: String
    }
`);
var coursesData = [
	{
		id: 1,
		title: "The Complete Node.js Developer Course",
		author: "Andrew Mead, Rob Percival",
		description:
			"Learn Node.js by building real-world applications with Node, Express, MongoDB, Mocha, and more!",
		topic: "Node.js",
		url: "https://codingthesmartway.com/courses/nodejs/"
	},
	{
		id: 2,
		title: "Node.js, Express & MongoDB Dev to Deployment",
		author: "Brad Traversy",
		description:
			"Learn by example building & deploying real-world Node.js applications from absolute scratch",
		topic: "Node.js",
		url: "https://codingthesmartway.com/courses/nodejs-express-mongodb/"
	},
	{
		id: 3,
		title: "JavaScript: Understanding The Weird Parts",
		author: "Anthony Alicea",
		description:
			"An advanced JavaScript course for everyone! Scope, closures, prototypes, this, build your own framework, and more.",
		topic: "JavaScript",
		url: "https://codingthesmartway.com/courses/understand-javascript/"
	}
];
var getCourse = function(args) {
	var id = args.id;
	// return coursesData.filter(course => {
	// 	return course.id == id;
	// })[0];
	return {
		code:999
	}
};
var getCourses = function(args) {
	if (args.topic) {
		var topic = args.topic;
	
		return coursesData.filter(course => course.topic === topic);
	} else {
		return coursesData;
	}
};
var root = {
	course: getCourse,
	courses: getCourses
};
// Create an express server and a GraphQL endpoint
var app = express();
app.use(
	"/graphql",
	express_graphql({
		schema: schema,
		rootValue: root,
		graphiql: true
	})
);
app.listen(4000, () =>
	console.log("Express GraphQL Server Now Running On localhost:4000/graphql")
);

// var express = require('express');
// var express_graphql = require('express-graphql');
// var { buildSchema } = require('graphql');

// // GraphQL schema
// var schema = buildSchema(`
//     type Query {
//         message: String
//     }
// `);
// // Root resolver
// var root = {
//     message: () => 'Hello World!'
// };
// // Create an express server and a GraphQL endpoint
// var app = express();
// app.use('/graphql', express_graphql({
//     schema: schema,
//     rootValue: root,
//     graphiql: true
// }));
// app.listen(4000, () => console.log('Express GraphQL Server Now Running On localhost:4000/graphql'));



// query abc {
//   course(id: 1) {
//     id
//   }
// }