Build a Node.js API
Build a Node.js API
Node.js
can be intimidating to beginners. But its flexible structure and lack
of strict guidelines makes it seem more complicated than it is.
This
tutorial is a quick and simple guide to Node.js, the Express framework,
and MongoDB, focusing on the fundamental REST routes and basic database
interaction. You’ll build a simple API boilerplate that can then be
used as the foundation for any app.
Who This Tutorial Is For:
You should have a basic understanding of REST APIs and CRUD operations,
plus basic JavaScript knowledge. I use ES6 (mainly fat-arrow
functions), but nothing too complex.
For this tutorial, you’ll create the skeleton of a back-end for a note-taking application — think You want to be able to do all four CRUD actions on your notes: create, read, update, and delete.
Setting Up
If you don’t have Node installed, .
In
a new directory, run npm init, and follow along with the prompts,
giving your app the name of ‘notable’ (or whatever else you might like).
npm init
Once that’s done, you should have a package.json ready to go in your directory. This means you can start installing the dependencies you need for your project.
You’re
going to use Express as your framework, MongoDB as the database, and a
package called body-parser to help deal with JSON requests.
npm install --save express mongodb body-parser
I
also highly recommend installing Nodemon as a dev dependency. It’s a
simple little package that automatically restarts your server when files
change.
If you run:
npm install --save-dev nodemon
You can then add the following script to package.json:
// package.json
"scripts": {
"dev": "nodemon server.js"
},
Your complete package.json should look like this:
// package.json
{
"name": "notable",
"version": "1.0.0",
"description": "",
"main": "server.js",
"scripts": {
"dev": "nodemon server.js"
},
"author": "",
"license": "ISC",
"dependencies": {
"body-parser": "^1.15.2",
"express": "^4.14.0",
"mongodb": "^2.2.16"
},
"devDependencies": {
"nodemon": "^1.11.0"
}
}
Now you can create your server.js file and start building your API.
Our Server
Let’s start by requiring all your dependencies in server.js.
// server.js
const express = require('express');
const MongoClient = require('mongodb').MongoClient;
const bodyParser = require('body-parser');
const app = express();
You’re
going to use the MongoClient to interact with your database. Note that
you also initialize your app as an instance of Express, your framework.
The last thing you need to do to get your server up and running is to tell your app to start listening for HTTP requests.
You can specify a port, and start the listening like so:
// server.js
const port = 8000;
app.listen(port, () => {
console.log('We are live on ' + port);
});
Now if you run npm run dev (or node server.js if you didn’t install Nodemon) you should see ‘We are live on port 8000’ in the terminal.
Your server is live. But it doesn’t do a whole lot. Or anything, really.
Let’s fix that.
CRUDdy Routes
For this example, you want to build 4 routes; to CREATE a note, to READ your notes, to UPDATE a note, and to DELETE a note.
This will give you a good idea of how to structure almost any basic route with Node.
To test your API, though, you need to mimic a client side making requests. To do so, you’ll use a great app called Postman. It allows you to make simple HTTP requests with custom bodies and parameters.
Install Postman, and let’s start setting up your routes.
Super Organized
Most Node.js tutorials (and many real apps) put all their routes in one big routes.js file.
This makes me a wee bit uncomfortable. In contrast, splitting up your
files into separate folders leads to good readability, and makes big
apps more manageable.
You don’t have a big app, but let’s do this right. Make the following directories: an app folder with a routes folder inside it, with an index.js and a note_routes.js file inside it.
In other words: root > app > routes > index.js and note_routes.js.
mkdir app cd app mkdir routes cd routes touch index.js touch note_routes.js
These directories may seem like overkill for your simple small app, but it’s always good to start with best practices.
Your First Route
Let’s start with the C in CRUD- create. How would you create a note?
Well,
before you do that, you have to build a bit more infrastructure. In
Express, routes are wrapped in a function, which takes the Express
instance and a database as arguments.
Like this:
// routes/note_routes.js
module.exports = function(app, db) {
};
You can then export this function through your index.js:
// routes/index.js
const noteRoutes = require('./note_routes');
module.exports = function(app, db) {
noteRoutes(app, db);
// Other route groups could go here, in the future
};
Then import it for use in server.js:
// server.js
const express = require('express');
const MongoClient = require('mongodb').MongoClient;
const bodyParser = require('body-parser');
const app = express();
const port = 8000;
require('./app/routes')(app, {});app.listen(port, () => {
console.log('We are live on ' + port);
});
Note that since you don’t have a database yet set up, you’re just passing in an empty object.
Okay, now you can make your CREATE route.
The syntax is simple:
// note_routes.js
module.exports = function(app, db) {
app.post('/notes', (req, res) => {
// You'll create your note here.
res.send('Hello')
});
};
When the app receives a post request
to the ‘/notes’ path, it will execute the code inside the callback-
passing in a request object (which contains the parameters or JSON of
the request) and a response object (used to reply).
You can test this by using Postman to send a POST request to localhost:8000/notes.
Nice! You created your first real route.
Next step is to add some parameters to your request and process them in your API and, finally, add in your database.
Request Parameters
In Postman, go to the Body tab and add some key-value pairs, after selecting the x-www-form-urlencoded radio button.
This will add encoded form data to your request, which you’ll be able to process with your API.
Now in your note_routes.js, let’s just log out the body.
// note_routes.js
module.exports = function(app, db) {
app.post('/notes', (req, res) => {
console.log(req.body) res.send('Hello')
});
};
Try sending the Postman request and you’ll see… undefined.
Unfortunately, Express can’t process URL encoded forms on its own. But you did install that body-parser package…
// server.
const express = require('express');
const MongoClient = require('mongodb').MongoClient;
const bodyParser = require('body-parser');
const app = express();
const port = 8000;
app.use(bodyParser.urlencoded({ extended: true }));
require('./app/routes')(app, {});
app.listen(port, () => {
console.log('We are live on ' + port);
});
Now you should see the body as an object in the terminal.
{ title: 'My Note Title', body: 'What a great note.' }
Last step to your preliminary route: set up the database, and then add your data in.
The easiest way to set up a Mongo database is through mLab: it’s free for the smallest size, and quite fast to setup.
Once you create an account and a MongoDB deployment, add a user to the database with a username and password:
then grab the URL here (the second one):
And in a directory config in the root of your project, create a db.js file.
mkdir config cd config touch db.js
Inside, add the URL:
module.exports = {
url : YOUR URL HERE
};
Don’t
forget to add your username and password (the ones from the database
user, not your mLab account) into the URL. (If you’re committing this
project to Github, be sure to include a .gitignore file like so, so you don’t share your password with everyone.)
Now in your server.js, you can use the MongoClient to connect to your DB, and use this to wrap your app setup:
// server.js
const express = require('express');
const MongoClient = require('mongodb').MongoClient;
const bodyParser = require('body-parser');
const db = require('./config/db');
const app = express();
const port = 8000;
app.use(bodyParser.urlencoded({ extended: true }));
MongoClient.connect(db.url, (err, database) => {
if (err) return console.log(err)
require('./app/routes')(app, database);
app.listen(port, () => {
console.log('We are live on ' + port);
});
})
That’s the last of your infrastructure setup! It’s all route-building from here.
Adding to your Database
MongoDB stores data in collections- which are exactly how they sound. In your case, you want to store your notes in a collection called — you guessed it — notes.
Since you pass in your database as the db argument in your routes, you can then access it like so:
db.collection('notes')
Creating a note is as simple as calling insert on your collection:
const note = { text: req.body.body, title: req.body.title}
db.collection('notes').insert(note, (err, results) => {
}
Once
the insert is complete (or has failed for whatever reason), you want to
either send back an error or send back the newly created note object.
Here’s the full note_routes.js:
// note_routes.js
module.exports = function(app, db) {
app.post('/notes', (req, res) => {
const note = { text: req.body.body, title: req.body.title };
db.collection('notes').insert(note, (err, result) => {
if (err) {
res.send({ 'error': 'An error has occurred' });
} else {
res.send(result.ops[0]);
}
});
});
};
Try it out! Send an x-www-form-urlencoded POST request with Postman, with a title and body set under the Body tab.
The response should look like this:
If you log into mLab, you should also see the created note in the database.
Your READ Route
Now you can pick up the pace a bit.
Say
you wanted to get back the note you just created, by navigating to
localhost:8000/notes/{the id}. In this case, that would be
localhost:8000/notes/585182bd42ac5b07a9755ea3.
(If you don’t have the ID for one of your notes, you can check on mLab or just create a new one).
Here’s what this would look like in note_routes.js:
// note_routes.js
module.exports = function(app, db) {
app.get('/notes/:id', (req, res) => {
});
app.post('/notes', (req, res) => {
const note = { text: req.body.body, title: req.body.title };
db.collection('notes').insert(note, (err, result) => {
if (err) {
res.send({ 'error': 'An error has occurred' });
} else {
res.send(result.ops[0]);
}
});
});
};
Just like before, you’re going to call a method on your database collection of notes. Here, it’s the aptly named findOne.
// note_routes.js
module.exports = function(app, db) {
app.get('/notes/:id', (req, res) => {
const details = { '_id': <ID GOES HERE> };
db.collection('notes').findOne(details, (err, item) => {
if (err) {
res.send({'error':'An error has occurred'});
} else {
res.send(item);
}
}); });
app.post('/notes', (req, res) => {
const note = { text: req.body.body, title: req.body.title };
db.collection('notes').insert(note, (err, result) => {
if (err) {
res.send({ 'error': 'An error has occurred' });
} else {
res.send(result.ops[0]);
}
});
});
};
You can grab the id from the URL parameters via req.params.id. However, if you try to just plop in the string into the <> above, it won’t work.
MongoDB requires not just an ID as a string, but as an ID object or, as they call it, an ObjectID.
Don’t worry, it’s an easy fix. Here’s the full code:
// note_routes.js
var ObjectID = require('mongodb').ObjectID;
module.exports = function(app, db) {
app.get('/notes/:id', (req, res) => {
const id = req.params.id;
const details = { '_id': new ObjectID(id) }; db.collection('notes').findOne(details, (err, item) => {
if (err) {
res.send({'error':'An error has occurred'});
} else {
res.send(item);
}
});
});
app.post('/notes', (req, res) => {
const note = { text: req.body.body, title: req.body.title };
db.collection('notes').insert(note, (err, result) => {
if (err) {
res.send({ 'error': 'An error has occurred' });
} else {
res.send(result.ops[0]);
}
});
});
};
Try it out with one of your note ID’s, and it should look like this:
Your DELETE Route
Deleting an object is actually pretty much the same as finding an object. You just use the remove function instead of the findOne. Here’s the full code. I’ve highlighted what’s different from your GET:
// note_routes.js
// ...
app.delete('/notes/:id', (req, res) => {
const id = req.params.id;
const details = { '_id': new ObjectID(id) };
db.collection('notes').remove(details, (err, item) => {
if (err) {
res.send({'error':'An error has occurred'});
} else {
res.send('Note ' + id + ' deleted!'); }
});
});
// ...
Your UPDATE Route
Last
one! The PUT is basically a hybrid between READ and CREATE. You find
the object, then update it accordingly. If you deleted your only note,
time to make another one!
The code:
// note_routes.js
// ...
app.put('/notes/:id', (req, res) => {
const id = req.params.id;
const details = { '_id': new ObjectID(id) };
const note = { text: req.body.body, title: req.body.title };
db.collection('notes').update(details, note, (err, result) => { if (err) {
Note
the imperfection with this code- if you fail to supply a body or title,
the PUT request will nullify those fields on the note in the database.
You
could easily add some conditional logic to update the fields only if
they’re present in the request- I left that out just to keep it simple.
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