[JAVA] [Introduction] Build MVC with Scala

Introduction

I will explain how to build an MVC structure on Scala's ultra-lightweight framework "Scalatra". ** Not only Scalatra, Scala has too few articles **.

As you can see from the tag, it is ** 8 ** only for Scalatra.

It's difficult to get started because it's overwhelmingly small ... Because of that, I usually write Swift, Go, Python, Ruby, but Scala is very interesting, but there is little literature. So this time I will start by building MVC so that I can develop web applications.

needs

I usually develop with "full stack framework" such as Rails, Django, Gin, but I don't have much freedom to say MVC structure. Rails is so black-boxed that I don't feel like I'm doing experiential programming.

Premise

This article covers the following:

--Those who have already built with bst etc.

Is targeted at.

Directory structure

There may be slight differences, but the directory structure should look like this:

src
├── main
│   ├── java
│   ├── resources
│   │   └── logback.xml
│   ├── scala
│   │   ├── ScalatraBootstrap.scala
│   │   └── com
│   │       └── example
│   │           └── app
│   │               └── ScalaServlet.scala
│   └── webapp
│       └── WEB-INF
│           └── web.xml
└── test
    ├── java
    ├── scala
    │   └── com
    │       └── example
    │           └── app
    │               └── MyScalatraServletTests.scala
    └── scala-2.12

As a beginner, I didn't know where to put what, but I thought of the Go package. Package is okay if you remember it as a namespace.

In other words, if you want to make it MVC, you can separate it with a package, and the next question is ** how can you explicitly build MVC while maintaining transparency **.

Of course, it may be better to build it under app. Extract the directory tree from earlier and change it as follows.

src
├── main
│   ├── java
│   ├── resources
│   │   └── logback.xml
│   ├── scala
│   │   ├── ScalatraBootstrap.scala
│   │   └── com
│   │       └── example
│   │           └── app
│   │               └── ScalaServlet.scala
│   │               └── view
│   │               └── controller
│   │               └── model
│   └── webapp
│       └── WEB-INF
│           └── web.xml
└── test

It is recommended to build MVC around ScalaServlet.scala because it is highly transparent and easy to develop.