[#]: collector: (lujun9972) [#]: translator: ( ) [#]: reviewer: ( ) [#]: publisher: ( ) [#]: url: ( ) [#]: subject: (Using Fedora to implement REST API in JavaScript: part 2) [#]: via: (https://fedoramagazine.org/using-fedora-to-implement-rest-api-in-javascript-part-2/) [#]: author: (Vaclav Keil https://fedoramagazine.org/author/vaclavk/) Using Fedora to implement REST API in JavaScript: part 2 ====== ![][1] In [part 1][2] 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: * Install a DB server * Build a new route * Connect a new datasource * Use Fedora terminal to send and receive data ### Generating an app Please refer to the [previous article][2] for more details. But to make things simple, change to your work directory and generate an app skeleton. ``` ``` $ cd our-work-directory $ npx express-generator –no-view –git /myApp $ cd myApp $ npm i ``` ``` ### Installing a database server In this part, we’ll install MariaDB database. MariaDB is the Fedora default database. ``` $ dnf module list mariadb | sort -u ## lists the streams available $ sudo dnf module install mariadb:10.3 ##10.4 is the latest ``` _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. ``` $ 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 ``` Now start the MariaDB service. ``` $ sudo systemctl start mariadb ``` If you’d like the service to start at boot, you can also enable it in systemd: ``` $ sudo systemctl enable mariadb ## start at boot ``` Next, setup the database as needed: ``` $ 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 ``` A database connector is needed to use the database with Node.js. ``` $ npm install mariadb ## installs MariaDB Node.js connector ``` 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. ``` $ npm install sequelize ## installs Sequelize ``` ### Connecting a new datasource Now, create a new _db_ folder and create a new file _sequelize.js_ there: ``` 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 ``` _Note: For the sake of completeness I‘m including a link to the related Github repo: _ 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: ``` sequelize.sync({ force: false }) ``` 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: ``` const sequelize = require('../db/sequelize') ``` ### Building new routes 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. ``` const User = require('../models/user') ``` 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: ``` const userRouter = require('./routes/user') app.use(userRouter) ``` Let‘s also remove the existing _usersRouter_. The _routes/users.js_ can be deleted too. ``` $ npm start ``` With the above command, you can launch your new app. ### Using the terminal to send and retrieve data Let’s create a new database record through the post method: ``` $ curl -d 'name=Adam' http://localhost:3000/users ``` To retrieve the data created through the API, do an HTTP GET request: ``` $ curl http://localhost:3000/users ``` 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._ ### More automation 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. ``` $ npm install sequelize-auto ``` A node.js connector is needed to use this one and we have it already installed for MariaDB. ### Conclusion 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. * * * _Photo by [Mazhar Zandsalimi][3] on [Unsplash][4]._ -------------------------------------------------------------------------------- via: https://fedoramagazine.org/using-fedora-to-implement-rest-api-in-javascript-part-2/ 作者：[Vaclav Keil][a] 选题：[lujun9972][b] 译者：[译者ID](https://github.com/译者ID) 校对：[校对者ID](https://github.com/校对者ID) 本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 [a]: https://fedoramagazine.org/author/vaclavk/ [b]: https://github.com/lujun9972 [1]: https://fedoramagazine.org/wp-content/uploads/2020/05/javascript-api-2-816x345.jpg [2]: https://fedoramagazine.org/using-fedora-to-quickly-implement-rest-api-with-javascript/ [3]: https://unsplash.com/@m47h4r?utm_source=unsplash&utm_medium=referral&utm_content=creditCopyText [4]: https://unsplash.com/s/photos/javascript?utm_source=unsplash&utm_medium=referral&utm_content=creditCopyText