Nap-db NPM | npm.io

Motivation

Need a simple way to map database tables to a DTO for an Expressjs prototype project and do not want to go through a steep learning curve that an ORM can present. The promise library pg-promise offers simple and flexible methods to efficiently interact with Postgres database. As such we chose to wrap the pg-promise functionality into a base class that can be easily extended to provide CRUD operations and map the class to a database table.

Documentation

nap-db documentation

Install

npm i nap-db

Usage

This module offers 2 classes

class DB - initialize database

class Model - CRUD and table mapping

Usage Examples

Define a User class:

const {Model} = require('nap-db');

const userSchema = {
    tableName: 'users',
    columns: [
        {
            name: 'email',
            type: 'varchar',
            length: 255,
            primary: true,
        },
        {
            name: 'password',
            type: 'varchar',
            length: 50,
            notNull: true,
        },
        {
            name: 'employee_id',
            type: 'int4',
            notNull: true,
        },
        {
            name: 'full_name',
            type: 'varchar',
            length: 50,
            notNull: true,
        },
        {
            name: 'role',
            type: 'varchar',
            length: 25,
            notNull: true,
        },
        {
            name: 'active',
            type: 'bool',
            notNull: true,
            default: true,
        },
    ],
    foreignKeys: [
        {
            hasRelations: [
                {
                    name: 'employee_id',
                },
            ],
            withColumns: [
                {
                    name: 'id',
                },
            ],
            withTable: 'employees',
        },
    ],
};

class Users extends Model {
    static #cs;

    // Deep copy userSchema to ensure it does not change
    constructor(db, pgp, schema = JSON.parse(JSON.stringify(userSchema))) {
        super(db, pgp, schema);

        // This is implemented this way to help remind developers to use a static variable
        if (!Users.#cs) {
            Users.#cs = this.createColumnsets();
            super.setColumnsets(Users.#cs);
        }
    }

    // Override Model.insert method.  For illustration only. Don't recommend doing validation here!!
    insert(dto) {
        dto.email = dto.email.toLowerCase();
        return super.insert(dto).catch((err) => Promise.reject(err));
    }
}

module.exports = Users;

Create a DB connection Object

const {DB} = require('nap-db');

// repositories in the databa
const repositories = {
    users: Users,
}

// Read DB connection object from configuration file
const connection = config.get('connection');
const db = DB.init(connection, repositories);

//Test the connection
db.connect()
    .then((obj) => {
        console.log('Connected to Postgres database!');
        obj.done(); // success, release connection;
    })
    .catch((error) => {
        console.log('Error connecting to Postgres database:', error.message);
    });

A typical connection object could be formatted as follows

{
    "connection": {
        "user": "<user_name>",
        "password": "<user-password>",
        "database": "<PostgreSQL database>",
        "host": "localhost",
        "port": 5432
    }
}