Mongoose Relationships Setup

Setup

Open your Terminal application and navigate to your ~/code/ga/lectures directory:

cd ~/code/ga/lectures

Make a new directory called mongoose-relationships, then enter this directory:

mkdir mongoose-relationships
cd mongoose-relationships

Create a node project along with its package.json file by using this command:

npm init -y

Open the contents of the directory in VS Code:

code .

Install mongoose and dotenv from NPM

To use mongoose in our application, we’ll first need to install the mongoose and dotenv packages from NPM:

npm i mongoose dotenv

Add the MongoDB Atlas connection string to your .env file

First, create a .env file in your project’s root directory:

touch .env

This file will be used to store any sensitive, secret information that the application needs to run, but that we don’t want to commit to GitHub. Database connection strings definitely qualify: we don’t want just anybody to be able to access our database using this string!

.env files are a simple list of key-value pairs defined like so:

SECRET_NUMBER=13
PASSWORD=12345

This will allow an application to access the SECRET_NUMBER and PASSWORD properties on a process.env object.

Paste your MongoDB Atlas connection string in the app’s .env file, assigning it to a MONGODB_URI environment variable. For example:

MONGODB_URI=mongodb+srv://<username>:<password>@sei-w0kys.azure.mongodb.net/?retryWrites=true

🚨 Do not use the above connection string in your application, it will not work.

There must be no spaces between MONGODB_URI, =, and your atlas connection string. It should be written as one continuous string.

This will make the connection string available in our application on the process.env.MONGODB_URI property.

Your connection string will default to a generic unnamed database, as indicated by the /? towards the end of the connection string. However, you must update this to your preferred database name.

In this application, that will be todos.

You can specify the preferred database name by adding it between the / and the ? in the connection string. That will make the full connection string for this app look something like this:

MONGODB_URI=mongodb+srv://<username>:<password>@sei-w0kys.azure.mongodb.net/todos?retryWrites=true

🚨 Again, do not use the above connection string in your application, it will not work.

This application builds on previous functionality for performing CRUD operations on a resource called Todos.

Add a .gitignore

Create a .gitignore file in your project’s root directory:

touch .gitignore

A .gitignore file is useful when working with Mongoose and MongoDB, as it prevents sensitive files (like your .env) from being committed to GitHub. In this application, the .env contains our database connection string. We’ll add the .env file to our .gitignore to prevent it from being committed to version control, avoiding the risk of exposing sensitive information online.

Add the following to your .gitignore file:

.env
node_modules

Defining a model

Let’s create a models directory and a file to define the todos resource:

mkdir models
touch models/todo.js

Add the following to models/todo.js:

// models/todo.js
const mongoose = require('mongoose');

const todoSchema = new mongoose.Schema({
  text: String,
  isComplete: Boolean,
});

const Todo = mongoose.model('Todo', todoSchema);

module.exports = Todo;

Query file

Create a queries.js file. We’ll use this file to execute various Mongoose operations:

touch queries.js

Add the following starter code to queries.js:

/*------------------------------ Starter Code ------------------------------*/

const dotenv = require('dotenv');
dotenv.config();

const mongoose = require('mongoose');
const Todo = require('./models/todo.js');

const connect = async () => {
  await mongoose.connect(process.env.MONGODB_URI);
  console.log('Connected to MongoDB');
  await runQueries();

  await mongoose.disconnect();
  console.log('Disconnected from MongoDB');
  process.exit();
};

connect();

/*----------------------------- Query Functions -----------------------------*/

const createTodo = async () => {
  const todoData = {
    text: 'learn React',
    isComplete: false,
  };
  const todo = await Todo.create(todoData);
  console.log('New todo:', todo);
};

const findTodos = async () => {
  const todos = await Todo.find({});
  console.log('All todos:', todos);
};

/*------------------------------- Run Queries -------------------------------*/

const runQueries = async () => {
  console.log('Queries running.');
  await createTodo();
};

This code establishes a connection to MongoDB and provides two functions to create and read todo resources in our database.

In this lesson we will build on that functionality, by adding additional data and showing how to create a relationship between the new data and the existing todo resource.