Querying PostgreSQL with Node.js made easy.
Created by: Lasha Tavartkiladze at Elva
License: MIT
npm install postgresql-query
Require and prepare module for querying.
var db = require('postgresql-query');
db.config({
username: '',
password: '',
host: '',
database: ''
});Query a database and get results in a callback function.
db.query(sql, values, callback);
db.query('SELECT * FROM albums WHERE artist_id = $1', 47, function (err, albums) {
});Or run multiple queries in specified order and get all results in a finalCallback functions.
db.query(tasks, finalCallback);
db.query([
['SELECT * FROM albums WHERE artist_id = $1', 47],
['SELECT * FROM genres WHERE artist_id = $1 AND mood = $2', [47, 'sad']],
['SELECT * FROM comments WHERE artist_id = $1', [47]]
], function (err, albums, genres, comments) {
});Query a database and use only the first row.
db.queryOne(sql, values, callback);
db.queryOne('SELECT * FROM artists WHERE id = $1', 47, function (err, artist) {
// artist.name
});Helper function to make it easy writing INSERT queries.
db.queryInsert(obj, callback);
db.queryInsert({
table: 'artists',
fields: {
first_name: 'John',
last_name: 'Doe',
country: 'Italy'
},
returnValue: '*'
}, function (err, insertedRow) {
});Above is the same as this:
db.queryOne('INSERT INTO artists (first_name, last_name, country) VALUES ($1, $2, $3) RETURNING *', ['John', 'Doe', 'Italy'], function (err, insertedRow) {
});Helper function to make it easy writing UPDATE queries.
db.queryUpdate(obj, callback);
db.queryUpdate({
table: 'artists',
fields: {
first_name: 'Mister',
last_name: 'Smith',
country: 'Spain'
},
where: {
id: 38
},
returnValue: '*'
}, function (err, updatedRow) {
});Above is the same as this:
db.queryOne('UPDATE artists SET first_name = $1, last_name = $2, country = $3 WHERE id = $4 RETURNING *', ['Mister', 'Smith', 'Spain', 38], function (err, updatedRow) {
});Helper function to make it easy dealing with transactions. It takes only a single parameter - a callback function and passed transaction object to it.
db.beginTransaction(function (transaction) {
});
Transaction object has three methods:
transaction.query();
transaction.commit();
transaction.rollback();transaction.query() is similar to db.query and can run multiple queries one after another. It also supports db.insertQuery() and db.updateQuery() syntax, so handy way of writing INSERT/UPDATE queries can be used here as well.
Example below starts a transaction, inserts a new artist and if that query was successfull adds two albums on that artist and then commits the transaction.
db.beginTransaction(function (transaction) {
transaction.query({
table: 'artist',
fields: {
first_name: 'Something'
},
returnValue: '*'
}, function (err, insertedArtist) {
if (err) { return transaction.rollback(); }
transaction.query([
{
table: 'albums',
fields: {
artist_id: insertedArtist.id,
title: 'Best Songs',
release_year: 2017
}
},
{
table: 'albums',
fields: {
artist_id: insertedArtist.id,
title: 'New Century',
release_year: 2016
}
}
], function (err) {
if (err) { return transaction.rollback(); }
transaction.commit();
});
});
});It isn't very pretty at first glance, but compared with native way of writing transactions (https://github.com/brianc/node-postgres/wiki/Transactions) it is the most pretty code ever written.
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