Groovy for Web Development

19. Groovy for Web Development (Grails, Ratpack)

Groovy is an excellent choice for web development due to its concise syntax, dynamic features, and seamless integration with Java libraries. In this tutorial, we'll explore two popular Groovy-based web frameworks: Grails and Ratpack.

Grails: A Full-Stack Web Framework

Grails is a high-productivity, full-stack web framework that leverages the Groovy language's power. It follows the Convention over Configuration (CoC) and Don't Repeat Yourself (DRY) principles, making it easy to build web applications quickly.

Setting Up a Grails Project:

Before we dive into Grails, make sure you have Grails installed. You can install it using the SDKMAN! tool or by downloading it from the Grails website.

grails create-app mywebapp
cd mywebapp

grails create-domain-class com.example.Book

package com.example

class Book {
    String title
    String author
    String genre
}

package com.example

import spock.lang.Specification

class MainSpec extends Specification {

    def "Adding two numbers"() {
        given:
        def main = new Main()

        when:
        def result = main.add(2, 3)

        then:
        result == 5
    }
}

grails run-app

Your Grails application is now running. Access it at 'http://localhost:8080/mywebapp/book/list'.

Ratpack: A Lightweight, Non-blocking Framework

Ratpack is a lightweight and asynchronous web framework for Groovy. It's known for its non-blocking and reactive programming model, making it suitable for high-performance applications.

Setting Up a Ratpack Project:

Before you start with Ratpack, make sure you have Java and Gradle installed. Ratpack projects are typically managed using Gradle.

mkdir myratpackapp
cd myratpackapp
gradle init --type java-library

dependencies {
    implementation 'org.ratpackframework:ratpack-core:2.7.0'
    testImplementation 'junit:junit:4.13.2'
}

// src/main/groovy/com/example/MyHandler.groovy

package com.example

import ratpack.func.Action
import ratpack.handling.Context

class MyHandler implements Action {
    @Override
    void execute(Context context) {
        context.render("Hello, Ratpack!")
    }
}

package com.example

import ratpack.groovy.GroovyRatpackMain

class MyRatpackApp {
    static void main(String[] args) {
        GroovyRatpackMain.run {
            handlers {
                get(new MyHandler())
            }
        }
    }
}

./gradlew run