接前面几篇文章,GraphQL 支持的数据操作有:
今天先看一下怎么执行一个简单的 Query 操作。
mkdir myapp
cd myapp
npm init (一路回车)
npm install @apollo/server graphql
创建 schema.graphql 文件,内容如下:
type User {
id: ID!
name: String!
email: String!
}
type Query {
users: [User],
user(id: ID!): User,
}
schema 文件主要包括:
创建 resolvers.js 文件,内容如下:
const user1 = {id: 1, name: 'user1', email: 'user1@gmail.com'};
const user2 = {id: 2, name: 'user2', email: 'user2@gmail.com'};
const user3 = {id: 3, name: 'user3', email: 'user3@gmail.com'};
const users = [user1, user2, user3];
const resolvers = {
Query: {
users: () => users,
user(obj, args, context, info) {
for (let user of users) {
if (user.id == args.id) {
return user;
}
}
return null;
},
},
};
module.exports = resolvers;
处理器文件主要包括
创建 server.js 文件,内容如下:
const { ApolloServer } = require('@apollo/server');
const { startStandaloneServer } = require('@apollo/server/standalone');
const fs = require("fs");
const typeDefs = fs.readFileSync('./schema.graphql').toString();
const resolvers = require('./resolvers');
const server = new ApolloServer({
typeDefs,
resolvers,
});
startStandaloneServer(server).then(function(data) {
console.log(`🚀 Server ready at ${data.url}`);
});
node server.js
服务启动后,访问 http://localhost:4000 进行测试。
查询操作
query GetUsers {
users {
id,
name,
email
}
}
查询结果
{
"data": {
"users": [
{
"id": "1",
"name": "user1",
"email": "user1@gmail.com"
},
{
"id": "2",
"name": "user2",
"email": "user2@gmail.com"
},
{
"id": "3",
"name": "user3",
"email": "user3@gmail.com"
}
]
}
}
查询操纵
query FindUser {
user(id: 1) {
id,
name,
email
}
}
查询结果
{
"data": {
"user": {
"id": "1",
"name": "user1",
"email": "user1@gmail.com"
}
}
}