Fedora - Using Fedora to implement REST API in JavaScript: part 2

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Fedora - Using Fedora to implement REST API in JavaScript: part 2 - xSicKxBot - 06-05-2020

Using Fedora to implement REST API in JavaScript: part 2

<div>In <a href="https://fedoramagazine.org/using-fedora-to-quickly-implement-rest-api-with-javascript/">part 1</a> previously, you saw how to quickly create a simple API service using Fedora Workstation, Express, and JavaScript. This article shows you the simplicity of how to create a new API. This part shows you how to:
<ul>
<li>Install a DB server</li>
<li>Build a new route</li>
<li>Connect a new datasource</li>
<li>Use Fedora terminal to send and receive data</li>
</ul>
 
<h2>Generating an app</h2>
Please refer to the <a href="https://fedoramagazine.org/using-fedora-to-quickly-implement-rest-api-with-javascript/">previous article</a> for more details. But to make things simple, change to your work directory and generate an app skeleton.
<pre class="wp-block-code"> <div class="codecolorer-container text default" style="overflow:auto;border:1px solid #9F9F9F;width:435px"><div class="text codecolorer" style="padding:5px;font:normal 12px/1.4em Monaco, Lucida Console, monospace">$ cd our-work-directory 
$ npx express-generator –no-view –git /myApp 
$ cd myApp 
$ npm i</div></div> </pre>
<h2>Installing a database server</h2>
In this part, we’ll install MariaDB database. MariaDB is the Fedora default database.
<pre class="wp-block-preformatted">$ dnf module list mariadb | sort -u ## lists the streams available
$ sudo dnf module install mariadb:10.3 ##10.4 is the latest</pre>
Note: the default profile is mariadb/server.
For those who need to spin up a Docker container a ready made container with Fedora 31 is available.
<pre class="wp-block-preformatted">$ docker pull registry.fedoraproject.org/f31/mariadb $ docker run -d --name mariadb_database -e MYSQL_USER=user -e MYSQL_PASSWORD=pass -e MYSQL_DATABASE=db -p 3306:3306 registry.fedoraproject.org/f31/mariadb</pre>
Now start the MariaDB service.
<pre class="wp-block-preformatted">$ sudo systemctl start mariadb</pre>
If you’d like the service to start at boot, you can also enable it in systemd:
<pre class="wp-block-preformatted">$ sudo systemctl enable mariadb ## start at boot</pre>
Next, setup the database as needed:
<pre class="wp-block-preformatted">$ mysql -u root -p ## root password is blank
MariaDB> CREATE DATABASE users;
MariaDB> create user dbuser identified by ‘123456‘;
MariaDB> grant select, insert, update, create, drop on users.* to dbuser;
MariaDB> show grants for dbuser;
MariaDB> \q</pre>
A database connector is needed to use the database with Node.js.
<pre class="wp-block-preformatted">$ npm install mariadb ## installs MariaDB Node.js connector</pre>
We’ll leverage Sequelize in this sample API. Sequelize is a promise-based Node.js ORM (Object Relational Mapper) for Postgres, MySQL, MariaDB, SQLite and Microsoft SQL Server.
<pre class="wp-block-preformatted">$ npm install sequelize ## installs Sequelize</pre>
<h2>Connecting a new datasource</h2>
Now, create a new db folder and create a new file sequelize.js there:
<pre class="wp-block-preformatted">const Sequelize = require('sequelize'), sequelize = new Sequelize(process.env.db_name || 'users', process.env.db_user || 'dbuser', process.env.db_pass || '123456', { host: 'localhost', dialect: 'mariadb', ssl: true
}) module.exports = sequelize</pre>
Note: For the sake of completeness I‘m including a link to the related Github repo: <a href="https://github.com/vaclav18/express-api-mariadb">https://github.com/vaclav18/express-api-mariadb</a>
Let‘s create a new file models/user.js. A nice feature of a Sequelize model is that it helps us to create the necessary tables and colums automatically. The code snippet responsible for doing this is seen below:
<pre class="wp-block-preformatted">sequelize.sync({
force: false
})</pre>
Note: never switch to true with a production database – it would drop your tables at app start!
We will refer to the earlier created sequelize.js this way:
<pre class="wp-block-preformatted">const sequelize = require('../db/sequelize')</pre>
<h2>Building new routes</h2>
Next, you’ll create a new file routes/user.js. You already have routes/users.js from the previous article. You can copy and paste the code in and proceed with editing it.
You’ll also need a reference to the previously created model.
<pre class="wp-block-preformatted">const User = require('../models/user')</pre>
Change the route path to /users and also create a new post method route.
Mind the async – await keywords there. An interaction with a database will take some time and this one will do the trick. Yes, an async function returns a promise and this one makes promises easy to use.
Note: This code is not production ready, since it would also need to include an authentication feature.
We‘ll make the new route working this way:
<pre class="wp-block-preformatted">const userRouter = require('./routes/user')
app.use(userRouter)</pre>
Let‘s also remove the existing usersRouter. The routes/users.js can be deleted too.
<pre class="wp-block-preformatted">$ npm start</pre>
With the above command, you can launch your new app.
<h2>Using the terminal to send and retrieve data</h2>
Let’s create a new database record through the post method:
<pre class="wp-block-preformatted">$ curl -d 'name=Adam' http://localhost:3000/users</pre>
To retrieve the data created through the API, do an HTTP GET request:
<pre class="wp-block-preformatted">$ curl http://localhost:3000/users</pre>
The console output of the curl command is a JSON array containing data of all the records in the Users table.
Note: This is not really the usual end result — an application consumes the API finally. The API will usually also have endpoints to update and remove data.
<h2>More automation</h2>
Let‘s assume we might want to create an API serving many tables. It‘s possible and very handy to automatically generate models for Sequelize from our database. Sequelize-auto will do the heavy lifting for us. The resulting files (models.js) would be placed and imported within the /models directory.
<pre class="wp-block-preformatted">$ npm install sequelize-auto</pre>
A node.js connector is needed to use this one and we have it already installed for MariaDB.
<h2>Conclusion</h2>
It‘s possible to develop and run an API using Fedora, Fedora default MariaDB, JavaScript and efficiently develop a solution like with a noSQL database. For those used to working with MongoDB or a similar noSQL database, Fedora and MariaDB are important open-source enablers.
<hr class="wp-block-separator" />
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</div>

https://www.sickgaming.net/blog/2020/05/18/using-fedora-to-implement-rest-api-in-javascript-part-2/