Koostage Node.js API alla 30 minutiga

Koostage Node.js API alla 30 minutiga

Node.js võib algajatele hirmutada. Kuid selle paindlik struktuur ja rangete juhiste puudumine näivad seda keerulisemana kui see on.

See õpetus on kiire ja lihtne juhend Node.js-i, Expressi raamistiku ja MongoDB-le, keskendudes põhilistele REST-marsruutidele ja andmebaasi põhisuhtlusele. Ehitate lihtsa API katlaplaadi, mida saab seejärel kasutada mis tahes rakenduse alusena.

Kellele see õpetus on mõeldud : teil peaks olema REST API-de ja CRUD-toimingute põhiteadmised ning lisaks JavaScripti põhiteadmised. Ma kasutan ES6 (peamiselt rasv-noole funktsioonid), kuid ei midagi liiga keerukat.

Selle õpetuse jaoks loote märkmete koostamise rakenduse taustsüsteemi skeleti - arvake, et Google Keep. Soovite, et märkmetes saaksite teha kõiki nelja CRUD-toimingut: luua, lugeda, värskendada ja kustutada.

Seadistan

Kui teil pole Node'i installitud, vaadake siit.

Käivitage uues kataloogis npm init ja järgige viipasid, andes rakendusele nime "tähelepanuväärne" (või mis iganes muu võib meeldida).

npm init

Kui see on tehtud, peaks teil olema oma kataloogis pakkimiseks valmis package.json . See tähendab, et võite alustada projekti jaoks vajalike sõltuvuste installimist.

Kasutate oma raamistikuna Expressi, andmebaasina MongoDB-d ja JSON-i taotluste lahendamiseks paketti nimega body-parser.

npm install --save express [email protected] body-parser

Samuti soovitan tungivalt installida Nodemoni kui Dev-sõltuvust. See on lihtne väike pakett, mis taaskäivitab teie serveri failide muutumisel.

Kui kandideerite:

npm install --save-dev nodemon

Seejärel saate lisada faili package.json järgmise skripti :

// package.json
 "scripts": { "dev": "nodemon server.js" },

Teie täielik package.json peaks välja nägema selline:

// 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" }}

Nüüd saate luua faili server.jsja alustage oma API loomist.

Meie server

Alustuseks nõuame kõiki teie sõltuvusi serveris.js.

// server.js
const express = require('express');const MongoClient = require('mongodb').MongoClient;const bodyParser = require('body-parser');
const app = express();

Kasutate oma andmebaasiga suhtlemiseks MongoClienti. Pange tähele, et lähtestate oma rakenduse ka oma raamistiku Expressi eksemplarina.

Viimane asi, mida peate oma serveri käivitamiseks tegema, on öelda rakendusele, et ta hakkaks HTTP taotlusi kuulama .

Saate määrata pordi ja alustada kuulamist nii:

// server.js
const port = 8000;
app.listen(port, () => { console.log('We are live on ' + port);});

Kui käivitate npm run dev (või sõlme server.js, kui te Nodemoni ei installinud), peaksite terminalis nägema 'We are live on port 8000'.

Teie server on aktiivne. Kuid see ei tee palju. Või midagi, tõesti.

Parandame selle.

CRUDdy marsruudid

Selle näite jaoks soovite ehitada 4 marsruuti; märkme loomiseks, märkmete lugemiseks, märkme värskendamiseks ja märkme kustutamiseks.

See annab teile hea ülevaate, kuidas Node'iga peaaegu kõiki põhilisi marsruute struktureerida.

API testimiseks peate siiski järele tegema taotlusi esitavat kliendipoolt. Selleks kasutate suurepärast rakendust nimega Postman. See võimaldab teil teha lihtsaid HTTP-päringuid kohandatud kehade ja parameetritega.

Installige Postman ja alustame teie marsruutide seadistamist.

Super organiseeritud

Enamik Node.js õpetusi (ja paljud reaalsed rakendused) panevad kõik marsruudid ühte suurde marsruudi.js faili. See teeb mind natuke ebamugavaks. Seevastu failide jagamine eraldi kaustadesse annab hea loetavuse ja muudab suured rakendused paremini hallatavaks.

Teil pole suurt rakendust, kuid teeme selle õigesti. Tehke järgmised kataloogid: rakenduste kaust, mille sees on marsruutide kaust, selle sees on index.js ja fail note_routes.js .

Teisisõnu: juur> rakendus> marsruudid> index.js ja note_routes.js.

mkdir appcd appmkdir routescd routestouch index.jstouch note_routes.js

Need kataloogid võivad teie lihtsa väikese rakenduse jaoks tunduda üle jõu käivatena, kuid alati on hea alustada headest tavadest.

Teie esimene marsruut

Alustame CRUD-i loomise C-ga. Kuidas saaksite märkuse luua?

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 configtouch 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); }); })

If you’re using the latest version of the MongoDB (3.0+), modify it like so:

// 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) // Make sure you add the database name and not the collection name const database = database.db("note-api") require('./app/routes')(app, database);
 app.listen(port, () => { console.log('We are live on ' + port); }); })

(Thanks to Alex Stroulger for the fix for 3.0)

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) { const collection = 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':  }; 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) { res.send({'error':'An error has occurred'}); } else { res.send(note); } }); });
// ...

Now you can update any of your notes, like so:

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.

API Complete

That’s it! You have a working Node API with each of the four major CRUD operations.

The goal of this tutorial was to give you a degree of familiarity with Express, Node, and MongoDB — you can use your simple app as a launching pad for more complex projects.

Kirjutan tulevikus õpetusi, et luua rohkem lihtsaid API-sid erinevates keeltes ja raamistikes. Kui olete huvitatud, vajutage nuppu Jälgi.

Kui sellest õpetusest oli teile abi, siis klõpsake allpool olevat rohelist südant - see tähendab palju. Jätke mulle ka tagasisidet või küsimusi.

Täname lugemast!