Following from Part 1 and Part 2, we had a working server but the changes are lost when server is restarted 😠. That sucked, so now time to database the, err ... data! 💾🙂🥫
(🥫 <- this is supposed to be a database)

NoSql databases

Compared to SQL databases with tables and rows, NoSql has collections and documents:

database > collections > documents

For example:

(database) data_db > 
  (collection) movies: [{}, {}, {}] > 
    (document) movie: { "id": "tt0110357", "name": "The Lion King", "genre": "animation"},

And did I mention no tables ?

For details on the whole SQL vs NoSql, check out this article:

Differences Between SQL And NoSQL Databases

Milecia ・ Apr 4 '19

#webdev #beginners #database #sql

What is diskdb ?

Diskdb allows you to use a file-based database with a mongodb-like API. Think SQLite for mongo. But why?

• Quick, simple, and fast - no more installation or config files; perfect for whipping a prototype server with some persistence
• db is stored along with your code, in regular JSON file, so easy to maintain without extra tooling
• No sign-up needed - No more signing up and getting tons of emails

why not?

• Very simple with limited API functionality
• Really not for Production

For the record, I loved mLab since it was easy, fast and free up to 500MB. But it was recently acquired by MongoDB and replaced with Atlas. I'll make a separate article for a cloud-based DB with Atlas as well.

Headstart

We'll use the base server files from the previous lesson here:
Quick REST API with Node + Express

Let's get started!

1. Create database file

Create /data/movies.json.
Data will be our database and movies will be our collection.

...
data/
    /movies.json
server.js
...

Init movies.json with an empty array

[]

2. Exclude data files from Nodemon

If you are using nodemon, you wouldn't want the server to restart for every change in the database files, i.e. an infinitely restarting server 😵

Add nodemonConfig to package.json, with a command to ignore /data.

"scripts": {...},
"nodemonConfig": { "ignore": [ "data/*" ] },
...

3. Install diskdb

$ npm install diskdb

4. Import and connect to db

The syntax is:
db.connect('/path/to/db-folder', ['collection-name']);

// server.js
...
// diskdb connection
const db = require('diskdb');
db.connect('./data', ['movies']);

This effectively creates a connection to the 'data' db, and 'movies' collection.

4. Add a movie to test out connection

// server.js
...
// add first movie
if (!db.movies.find().length) {
   const movie = { id: "tt0110357", name: "The Lion King", genre: "animation" };
   db.movies.save(movie);
}
console.log(db.movies.find());

Nice and simple!
db.[collection].save(object) to add a document
db.[collection].find() to get all current docs

We're only adding this movie if the db is initially empty,
or else we'll end up with lots of Lion Kings with different _ids 😨
🦁🦁🦁🦁🦁🦁🦁

This should give you something like this

Successfully connected to : ./data
[ { id: 'tt0110357',
    name: 'The Lion King',
    genre: 'animation',
    _id: 'fed8db042fac4892bb96fd72ad13290e' } ]

Notice that it added a _id to our item, used as a global id like in mongodb.

5. CRUD to REST to DB

Now that you've seen Create and Read all, here's the complete roundup of the db operations in diskdb syntax for each CRUD - REST route handler.

For details on the REST - HTTP table and route handlers, check out prev post .

Also note that collection here is movies for our example.

6. Changing to diskdb operations

Using the table, we could now replace all of our memory-based operations with the db equivalent.

i. Create ➕

server.post("/items", (req, res) => {
   const item = req.body;
   console.log('Adding new item: ', item);
   // add new item to db
   db.movies.save(item);
   // return updated list
   res.json(db.movies.find());
});

ii. Read one 🕵️

server.get("/items/:id", (req, res) => {
   const itemId = req.params.id;
   const items = db.movies.find({ id: itemId });
   if (items.length) {
      res.json(items);
   } else {
      res.json({ message: `item ${itemId} doesn't exist` })
   }
});

iii. Read all 🕵️

server.get("/items", (req, res) => {
   res.json(db.movies.find());
});

iv. Update ✏️

server.put("/items/:id", (req, res) => {
   const itemId = req.params.id;
   const item = req.body;
   console.log("Editing item: ", itemId, " to be ", item);

   db.movies.update({ id: itemId }, item);

   res.json(db.movies.find());
});

v. Delete ❌

server.delete("/items/:id", (req, res) => {
   const itemId = req.params.id;
   console.log("Delete item with id: ", itemId);

   db.movies.remove({ id: itemId });

   res.json(db.movies.find());
});

Test it out

Add a new one.

$ curl -X POST -H "Content-Type: application/json" --data '{"id": "tt0109830", "name": "Forrest Gump", "genre": "drama"}' http://localhost:4000/items

Fetch all.
From browser: http://localhost:4000/items

Fetch one.
From browser: http://localhost:4000/items/tt0110357

Update it.
Maybe you think Forrest Gump is an action movie, because of all the war sequences and all the running. 🔫🎖️🏃‍♂️

$ curl -X PUT -H "Content-Type: application/json" --data '{"genre": "action"}' http://localhost:4000/items/tt0109830

...{"id":"tt0109830","name":"Forrest Gump","genre":"action"}...

Delete it.

curl -X DELETE http://localhost:4000/items/tt0468569

Some cleanup 🧹

Db is working! Now we can remove the unneeded static data file: data.js.
Don't forget to remove the line from server.js that imports it

let data = require('./data');

Here's the complete Code

Quick db with Node + Express + diskdb

"Okay, that was nice. But what can I do with this? "

✅ Serving HTML files
✅ REST API
✅ Database persistence

Now, this is an actual server for a small project. Add more routes, save some data in the db through API requests. And when you want to reset the db, just reset movies.json to [].

Next up:

(In progress): Using a Cloud DB with Node and Express

This article is part of a Node+Express series I'm working on.

For the meantime, if you can't get enough of Node+Express 🤓,
checkout my Node workshop (Gihub repo and slides):

$ git checkout dev
$ node server.js

$ git checkout master
$

Here we discussed:

• Using Node and Express
• Routing, request and response
• Building a REST API
• Server-rendered templates
• Connecting to a NoSQL (mongo) database
• Using external APIs, such as Spotify
• and much more!

Happy server-ing! 🤓

Now, if I could find a better emoji for a database than 🥫