Setup Knex with Node.js
Create and initialize your a directory for your Express application.
$ mkdir node-knex-demo
$ cd node-knex-demo
$ npm init
Knex is a SQL query builder, mainly used for Node.js applications with built in model schema creation, table migrations, connection pooling and seeding.
Install knex
globally on your local computer.
$ npm install knex -g
This will allow us to use knex
as a command line tool that helps you create and manage your knex files.
In addition, you will need to also install the knex
module locally to use in your project.
$ npm install knex --save
For our example, we're going to be connecting to a PostgreSQL database, we'll need to install the pg
module.
$ npm install pg --save
We can start by creating a knexfile.js
in the root of your project which will act as our configuration for different environments, (e.g. – local development vs production).
$ knex init
This will create a knexfile.js
with the different configurations for the different environments.
Generated output knexfile.js
.
module.exports = {
development: {
client: 'sqlite3',
connection: {
filename: './dev.sqlite3'
}
},
staging: {
client: 'postgresql',
connection: {
database: 'my_db',
user: 'username',
password: 'password'
},
pool: {
min: 2,
max: 10
},
migrations: {
tableName: 'knex_migrations'
}
},
production: {
client: 'postgresql',
connection: {
database: 'my_db',
user: 'username',
password: 'password'
},
pool: {
min: 2,
max: 10
},
migrations: {
tableName: 'knex_migrations'
}
}
};
Edit your development
settings in knexfile.js
to point to your postgres database, using your db username and password. DON'T FORGET TO CREATE YOUR DATABASE LOCALLY!
Example development
config object
{
development: {
client: 'pg',
connection: {
host : '127.0.0.1',
user : '[db_username]',
password : '[db_password]',
database : '[db_name]',
charset: 'utf8'
},
migrations: {
directory: __dirname + '/knex/migrations',
},
seeds: {
directory: __dirname + '/knex/seeds'
}
}
}
We want to create a knex
directory at the root of our project to hold our migrations
and seeds
scripts. Inside of the knex
directory, we need a knex.js
file to hold the single instance of the knex
module with the correct environment config.
$ mkdir knex
$ mkdir knex/migrations
$ mkdir knex/seeds
$ touch knex/knex.js
At this point, our project structure should look like this:
.
├── knex
│ └── migrations
│ └── seeds
│ └── knex.js
└── knexfile.js
└── package.json
For more information on migrations and seeds with knex, checkout the knex migrations and seeds guide.
Example knex.js
const environment = process.env.ENVIRONMENT || 'development'
const config = require('../knexfile.js')[environment];
module.exports = require('knex')(config);
$ npm install express --save
Now let's create a server.js
file in the root of your project. Create your express application how you normally would, for this example the server listening on port 3001
. Let's also create a super basic GET
endpoint to query our db.
const express = require('express');
const PORT = process.env.PORT || 3001;
const knex = require('./knex/knex.js');
const app = express();
app.get('/tasks', (req, res) => {
// use the knex variable above to create dynamic queries
});
app.listen(PORT, () => {
console.log(`Listening on port: ${PORT}`);
});
Start the server:
$ node server.js