我正尝试创建一个PostgreSQL数据库,因此我安装了PostgreSQL并使用initdb /usr/local/pgsql/data
启动了服务器,然后使用postgres -D /usr/local/pgsql/data
启动了该实例。现在我该如何通过Node与其交互呢?例如,connectionstring
是什么,或者我如何能够找到它。
我正尝试创建一个PostgreSQL数据库,因此我安装了PostgreSQL并使用initdb /usr/local/pgsql/data
启动了服务器,然后使用postgres -D /usr/local/pgsql/data
启动了该实例。现在我该如何通过Node与其交互呢?例如,connectionstring
是什么,或者我如何能够找到它。
这是一个我用来连接Node.js和Postgres数据库的示例。
我使用的Node.js接口可以在此处找到https://github.com/brianc/node-postgres
var pg = require('pg');
var conString = "postgres://YourUserName:YourPassword@localhost:5432/YourDatabase";
var client = new pg.Client(conString);
client.connect();
//queries are queued and executed one after another once the connection becomes available
var x = 1000;
while (x > 0) {
client.query("INSERT INTO junk(name, a_number) values('Ted',12)");
client.query("INSERT INTO junk(name, a_number) values($1, $2)", ['John', x]);
x = x - 1;
}
var query = client.query("SELECT * FROM junk");
//fired after last row is emitted
query.on('row', function(row) {
console.log(row);
});
query.on('end', function() {
client.end();
});
//queries can be executed either via text/parameter values passed as individual arguments
//or by passing an options object containing text, (optional) parameter values, and (optional) query name
client.query({
name: 'insert beatle',
text: "INSERT INTO beatles(name, height, birthday) values($1, $2, $3)",
values: ['George', 70, new Date(1946, 02, 14)]
});
//subsequent queries with the same name will be executed without re-parsing the query plan by postgres
client.query({
name: 'insert beatle',
values: ['Paul', 63, new Date(1945, 04, 03)]
});
var query = client.query("SELECT * FROM beatles WHERE name = $1", ['john']);
//can stream row results back 1 at a time
query.on('row', function(row) {
console.log(row);
console.log("Beatle name: %s", row.name); //Beatle name: John
console.log("Beatle birth year: %d", row.birthday.getYear()); //dates are returned as javascript dates
console.log("Beatle height: %d' %d\"", Math.floor(row.height / 12), row.height % 12); //integers are returned as javascript ints
});
//fired after last row is emitted
query.on('end', function() {
client.end();
});
更新:- query.on
函数现已弃用,因此上述代码将无法按预期工作。解决方法请参考:query.on is not a function
现代简单的方法:pg-promise:
const pgp = require('pg-promise')(/* initialization options */);
const cn = {
host: 'localhost', // server name or IP address;
port: 5432,
database: 'myDatabase',
user: 'myUser',
password: 'myPassword'
};
// alternative:
// var cn = 'postgres://username:password@host:port/database';
const db = pgp(cn); // database instance;
// select and return a single user name from id:
db.one('SELECT name FROM users WHERE id = $1', [123])
.then(user => {
console.log(user.name); // print user name;
})
.catch(error => {
console.log(error); // print the error;
});
// alternative - new ES7 syntax with 'await':
// await db.one('SELECT name FROM users WHERE id = $1', [123]);
另请参阅:如何正确声明您的数据库模块。
只是补充一个不同的选项 - 我使用Node-DBI连接到PG,但也可以连接到MySQL和sqlite。 Node-DBI还包括构建select语句的功能,这对于在运行时进行动态操作非常方便。
快速示例(使用存储在另一个文件中的配置信息):
var DBWrapper = require('node-dbi').DBWrapper;
var config = require('./config');
var dbConnectionConfig = { host:config.db.host, user:config.db.username, password:config.db.password, database:config.db.database };
var dbWrapper = new DBWrapper('pg', dbConnectionConfig);
dbWrapper.connect();
dbWrapper.fetchAll(sql_query, null, function (err, result) {
if (!err) {
console.log("Data came back from the DB.");
} else {
console.log("DB returned an error: %s", err);
}
dbWrapper.close(function (close_err) {
if (close_err) {
console.log("Error while disconnecting: %s", close_err);
}
});
});
config.js:
var config = {
db:{
host:"plop",
database:"musicbrainz",
username:"musicbrainz",
password:"musicbrainz"
},
}
module.exports = config;
database:
参数,最终添加上它修复了连接。 - RAM237一个解决方案是使用如下的客户端池:pool
:
const { Pool } = require('pg');
var config = {
user: 'foo',
database: 'my_db',
password: 'secret',
host: 'localhost',
port: 5432,
max: 10, // max number of clients in the pool
idleTimeoutMillis: 30000
};
const pool = new Pool(config);
pool.on('error', function (err, client) {
console.error('idle client error', err.message, err.stack);
});
pool.query('SELECT $1::int AS number', ['2'], function(err, res) {
if(err) {
return console.error('error running query', err);
}
console.log('number:', res.rows[0].number);
});
连接字符串是一个形如以下格式的字符串:
postgres://[user[:password]@][host][:port][/dbname]
(方括号中的部分可以选择包含或排除)
一些有效连接字符串的示例:
postgres://localhost
postgres://localhost:5432
postgres://localhost/mydb
postgres://user@localhost
postgres://user:secret_password@localhost
postgres://localhost
通常有效,因为它使用默认的端口号、用户名和无密码。如果数据库是使用特定帐户启动的,则可能需要使用postgres://pg@localhost
或postgres://postgres@localhost
。npx @databases/pg-test start
。这将在Docker容器中启动一个Postgres服务器,然后为您打印出连接字符串。但是请注意,pg-test
数据库仅用于测试,如果计算机重新启动,则会丢失所有数据。@databases/pg
。const createPool = require('@databases/pg');
const {sql} = require('@databases/pg');
// If you're using TypeScript or Babel, you can swap
// the two `require` calls for this import statement:
// import createPool, {sql} from '@databases/pg';
// create a "pool" of connections, you can think of this as a single
// connection, the pool is just used behind the scenes to improve
// performance
const db = createPool('postgres://localhost');
// wrap code in an `async` function so we can use `await`
async function run() {
// we can run sql by tagging it as "sql" and then passing it to db.query
await db.query(sql`
CREATE TABLE IF NOT EXISTS beatles (
name TEXT NOT NULL,
height INT NOT NULL,
birthday DATE NOT NULL
);
`);
const beatle = {
name: 'George',
height: 70,
birthday: new Date(1946, 02, 14),
};
// If we need to pass values, we can use ${...} and they will
// be safely & securely escaped for us
await db.query(sql`
INSERT INTO beatles (name, height, birthday)
VALUES (${beatle.name}, ${beatle.height}, ${beatle.birthday});
`);
console.log(
await db.query(sql`SELECT * FROM beatles;`)
);
}
run().catch(ex => {
// It's a good idea to always report errors using
// `console.error` and set the process.exitCode if
// you're calling an async function at the top level
console.error(ex);
process.exitCode = 1;
}).then(() => {
// For this little demonstration, we'll dispose of the
// connection pool when we're done, so that the process
// exists. If you're building a web server/backend API
// you probably never need to call this.
return db.dispose();
});
您可以在https://www.atdatabases.org/docs/pg找到更详细的使用node.js查询Postgres的指南。
Slonik 是对 Kuberchaun 和 Vitaly 提出的答案的一种替代方案。
Slonik 实现了 安全连接处理;您可以创建一个连接池,连接的打开/处理将由 Slonik 自动完成。
import {
createPool,
sql
} from 'slonik';
const pool = createPool('postgres://user:password@host:port/database');
return pool.connect((connection) => {
// You are now connected to the database.
return connection.query(sql`SELECT foo()`);
})
.then(() => {
// You are no longer connected to the database.
});
postgres://user:password@host:port/database
是您的连接字符串(或更加规范的连接 URI 或 DSN)。
这种方法的好处是,您的脚本可以确保您永远不会意外地留下悬挂的连接。
使用 Slonik 的其他好处包括:
"pg_connection.js
const PgConnection = require('postgresql-easy');
const dbConfig = require('./config/db');
const pg = new PgConnection(dbConfig);
module.exports = pg;
./config/db.js
module.exports = {
database: 'your db',
host: 'your host',
port: 'your port',
user: 'your user',
password: 'your pwd',
}
your_handler.js
const pg_conctn = require('./pg_connection');
pg_conctn.getAll('your table')
.then(res => {
doResponseHandlingstuff();
})
.catch(e => {
doErrorHandlingStuff()
})