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209 lines
6.7 KiB
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209 lines
6.7 KiB
Markdown
[#]: collector: (lujun9972)
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[#]: translator: ( )
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[#]: reviewer: ( )
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[#]: publisher: ( )
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[#]: url: ( )
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[#]: subject: (Using Fedora to implement REST API in JavaScript: part 2)
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[#]: via: (https://fedoramagazine.org/using-fedora-to-implement-rest-api-in-javascript-part-2/)
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[#]: author: (Vaclav Keil https://fedoramagazine.org/author/vaclavk/)
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Using Fedora to implement REST API in JavaScript: part 2
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======
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![][1]
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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:
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* Install a DB server
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* Build a new route
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* Connect a new datasource
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* Use Fedora terminal to send and receive data
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### Generating an app
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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.
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```
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```
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$ cd our-work-directory
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$ npx express-generator –no-view –git /myApp
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$ cd myApp
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$ npm i
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```
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```
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### Installing a database server
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In this part, we’ll install MariaDB database. MariaDB is the Fedora default database.
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```
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$ dnf module list mariadb | sort -u ## lists the streams available
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$ sudo dnf module install mariadb:10.3 ##10.4 is the latest
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```
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_Note: the default profile is mariadb/server_.
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For those who need to spin up a Docker container a ready made container with Fedora 31 is available.
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```
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$ docker pull registry.fedoraproject.org/f31/mariadb
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$ 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
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```
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Now start the MariaDB service.
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```
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$ sudo systemctl start mariadb
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```
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If you’d like the service to start at boot, you can also enable it in systemd:
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```
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$ sudo systemctl enable mariadb ## start at boot
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```
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Next, setup the database as needed:
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```
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$ mysql -u root -p ## root password is blank
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MariaDB> CREATE DATABASE users;
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MariaDB> create user dbuser identified by ‘123456‘;
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MariaDB> grant select, insert, update, create, drop on users.* to dbuser;
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MariaDB> show grants for dbuser;
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MariaDB> \q
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```
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A database connector is needed to use the database with Node.js.
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```
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$ npm install mariadb ## installs MariaDB Node.js connector
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```
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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.
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```
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$ npm install sequelize ## installs Sequelize
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```
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### Connecting a new datasource
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Now, create a new _db_ folder and create a new file _sequelize.js_ there:
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```
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const Sequelize = require('sequelize'),
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sequelize = new Sequelize(process.env.db_name || 'users', process.env.db_user || 'dbuser', process.env.db_pass || '123456', {
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host: 'localhost',
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dialect: 'mariadb',
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ssl: true
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})
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module.exports = sequelize
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```
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_Note: For the sake of completeness I‘m including a link to the related Github repo: <https://github.com/vaclav18/express-api-mariadb>_
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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:
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```
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sequelize.sync({
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force: false
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})
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```
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Note: never switch to true with a production database – it would _drop your tables at app start_!
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We will refer to the earlier created sequelize.js this way:
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```
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const sequelize = require('../db/sequelize')
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```
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### Building new routes
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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.
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You’ll also need a reference to the previously created model.
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```
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const User = require('../models/user')
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```
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Change the route path to _/users_ and also create a new **post** method route.
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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.
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_Note: This code is not production ready, since it would also need to include an authentication feature._
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We‘ll make the new route working this way:
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```
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const userRouter = require('./routes/user')
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app.use(userRouter)
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```
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Let‘s also remove the existing _usersRouter_. The _routes/users.js_ can be deleted too.
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```
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$ npm start
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```
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With the above command, you can launch your new app.
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### Using the terminal to send and retrieve data
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Let’s create a new database record through the post method:
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```
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$ curl -d 'name=Adam' http://localhost:3000/users
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```
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To retrieve the data created through the API, do an HTTP GET request:
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```
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$ curl http://localhost:3000/users
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```
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The console output of the curl command is a JSON array containing data of all the records in the _Users_ table.
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_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._
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### More automation
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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.
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```
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$ npm install sequelize-auto
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```
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A node.js connector is needed to use this one and we have it already installed for MariaDB.
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### Conclusion
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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.
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* * *
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_Photo by [Mazhar Zandsalimi][3] on [Unsplash][4]._
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--------------------------------------------------------------------------------
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via: https://fedoramagazine.org/using-fedora-to-implement-rest-api-in-javascript-part-2/
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作者：[Vaclav Keil][a]
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选题：[lujun9972][b]
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译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]: https://fedoramagazine.org/author/vaclavk/
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[b]: https://github.com/lujun9972
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[1]: https://fedoramagazine.org/wp-content/uploads/2020/05/javascript-api-2-816x345.jpg
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[2]: https://fedoramagazine.org/using-fedora-to-quickly-implement-rest-api-with-javascript/
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[3]: https://unsplash.com/@m47h4r?utm_source=unsplash&utm_medium=referral&utm_content=creditCopyText
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[4]: https://unsplash.com/s/photos/javascript?utm_source=unsplash&utm_medium=referral&utm_content=creditCopyText
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