撰寫
用 express 建立簡單 GraphQL server（postgresql 資料庫）
建立 Project
init 一個 project
$npm init -y
建立 es6 babel
$npm install babel-cli babel-preset-env babel-watch --save
建立 .babelrc
{
"presets": ["env"]
}
修改 package.json
{
// ....
"scripts": {
"dev": "babel-watch server.js",
"test": "echo \"Error: no test specified\" && exit 1"
},
// ....
}
確認 postgresql table
[email protected]~$ psql -d nodetest psql (9.6.9) Type "help" for help. nodetest=# select id, username, email from users; id | username | email ----+----------+------------------------ 4 | Brian | [email protected] 14 | Cathy | [email protected] 1 | Jerry | [email protected] 33 | Irene | [email protected] (4 rows)
加入 express, postgresql 跟 graphql
$npm install express cors pg-promise --save $npm install graphql graphql-tools apollo-server-express --save
server.js
import express from 'express';
import bodyParse from 'body-parser';
import { graphqlExpress, graphiqlExpress } from 'apollo-server-express';
import cors from 'cors';
//import schema from './schema';
import schema from './pg-schema';
const app = express();
app.use('*', cors());
app.use('/graphiql', graphiqlExpress({
endpointURL: "/graphql"
}));
app.use('/graphql', bodyParse.json(), graphqlExpress({ schema }));
app.listen(4000, () => console.log("express server running on port 4000 "));
使用 cors() middleware 避免 cors 問題
endpoint 有 /graphiql 跟 /graphql
pg-schema.js
import { makeExecutableSchema } from 'graphql-tools';
import resolvers from './pg-resolver';
const typeDefs = [`
type User {
id: String
username: String
email: String
}
type Query {
users: [User]
}
`];
const schema = makeExecutableSchema({
typeDefs,
resolvers
});
export default schema;
定義 schema
pg-resolver.js
import psql from './psql-adapter';
const resolvers = {
Query: {
users: () => {
const userQuery = 'select id, username, email from users';
return psql.manyOrNone(userQuery);
}
}
}
export default resolvers;
簡單 resolver, sql 來 query user table
psql-adapter.js
import pgPromise from 'pg-promise';
const connectStr = {
host: 'localhost',
port: 5432,
database: 'nodetest',
user: 'xxxxx',
password: 'yyyy'
};
const pgp = pgPromise({});
const psql = pgp(connectStr);
export default psql;
執行 server
[email protected] dev /Users/jerryhsieh/Developer/Web/graphql/graphql-nodejs
> babel-watch server.js
express server running on port 4000
>>> RESTARTING <<<
express server running on port 4000
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