EN
Express.js / PostgreSQL - rows pagination
0 points
In this article, we would like to show you how to paginate data rows in PostgreSQL using Express.js.
Note:
Pagination consists in dividing data into pages and sending only those rows that the client currently needs - we do not have to send all data at once.
Note: at the end of this article you can find database preparation SQL queries.
xxxxxxxxxx1
const express = require('express');2
const { Pool } = require('pg');3
4
const app = express();5
6
const pool = new Pool({7
host: '127.0.0.1',8
user: 'my_username',9
database: 'my_database',10
password: 'my_password',11
port: 5432,12
max: 10, // max number of clients in the pool13
idleTimeoutMillis: 30000, // how long a client is allowed to remain idle before being closed14
connectionTimeoutMillis: 200015
});16
17
app.get('/users', async (req, res) => {18
try {19
const client = await pool.connect(); // creates connection20
const { page, size } = req.query;21
const query = `22
SELECT *23
FROM "users"24
ORDER BY "users"."id"25
LIMIT $226
OFFSET (($1 - 1) * $2);27
`;28
try {29
const { rows } = await client.query(query, [page, size]); // sends query30
res.status(200).json(rows);31
} finally {32
await client.release(); // releases connection33
}34
} catch (error) {35
return res.status(500).json(error);36
}37
});38
39
app.listen(3000, () => {40
console.log('listening at http://localhost:3000');41
});
create_tables.sql file:
xxxxxxxxxx1
CREATE TABLE "users" (2
"id" SERIAL,3
"name" VARCHAR(50) NOT NULL,4
"surname" VARCHAR(50) NOT NULL,5
"department_id" INTEGER,6
"salary" DECIMAL(15,2) NOT NULL,7
PRIMARY KEY ("id")8
);insert_data.sql file:
xxxxxxxxxx1
INSERT INTO "users"2
( "name", "surname", "department_id", "salary")3
VALUES4
('John', 'Stewart', 1, '2000.00'),5
('Chris', 'Brown', 3, '2000.00'),6
('Chris', 'Lewis', 3, '2000.00'),7
('Kate', 'Lewis', 3, '2000.00'),8
('Kate', 'Stewart', 3, '2000.00'),9
('Ailisa', 'Lewis', 3, '2000.00'),10
('Ailisa', 'Gomez', 3, '3000.00'),11
('Gwendolyn', 'James', 2, '3000.00'),12
('Simon', 'James', 2, '2000.00'),13
('Simon', 'Brown', 3, '2000.00'),14
('Simon', 'Collins', 3, '3000.00');