Grails in Action

Envelon s.r.o.

• Young start-up company
• Prague / Munich (Germany)
• Development on demand
• Own projects
• Web development - Grails
• Desktop app development

Matous Kucera

• Bc. computer science CTU Prague
• MSc. software engineering TU Munich (Germany)
• Co-founder of Envelon s.r.o.
• 4 - ? years of experiences with Grails

Grails

• Web application framework
• Rapid development framework
• Open source
• Convention over configuration

Grails 2.2.3

Why Grails?

• Built on enterprise strong frameworks / Languages
  • Java
  • Spring
  • Hibernate
• Groovy
  • Advanced JVM Language
• Plug-in System
  • ~ 950 plugins
• Rapid development framework
• Good Documentation

Groovy

Do I need it?

No

• You can start with Grails without knowledge of Groovy

Yes

• You should leverage Groovy!
• 99% of your future code in Grails

What's the Advantage of Groovy

                    
package com.envelon.note

import com.envelon.pencil.Pencil
import org.joda.time.DateTime

class Note extends AbstractNote {

    String content
    String creator
    DateTime timestamp

    public String toString() {
        return "[$timestamp - $creator] $content"
    }
}
                    
                

But There is More!

• Lambda Calculus & Closures
• Collections
• Elvis Operator
• Null Operand
• String Templates
• Meta Class

Grails Architecture

Model View Controller Pattern

Grails Domain Classes

~ Model

grails-app/domain/.../*.groovy

                    
package com.envelon.miracleBalnk

import com.envelon.miracleBalnk.BankGroup
import com.envelon.miracleBalnk.client.Client
import com.envelon.miracleBalnk.crew.Director

class Bank {
    String name
    Director director
    BankGroup bankGroup

    static hasMany = [clients: Client]
    static belongsTo = [BankGroup]

    static constraints = {
        name nullable: false, blank: false, unique: true
    }
}

                    
                

Grails Services

~ Controller

grails-app/services/.../*.groovy

                    
class BankService {
    static transactional = true
    def acountService

    def bankrupt() {
        def acounts = acountService.acounts
        def money = 0

        acounts.each { Account account ->
            money += account.money
            account.money = 0
            account.save()
        }

        money // no return needed
    }
}
                    
                

Grails Controllers

~ View

grails-app/controllers/.../*.groovy

                    
class AccountController {

    def springSecurityService

    def index() {
        def user = springSecurityService.currentUser
        redirect(action: "show", id: user.account?.id)
    }

    def show(Long id) {
        def account = Account.get(id)

        [account: account]
    }
}
                    
                

Grails gsp

~ View

grails-app/views/.../*.gsp

                    
...


    

...
                    
                

GORM

Grails Object Relational Mapping

• Dynamic finders
• Criteria builder

Scaffolding

Templates for controllers, views and more

Grails Plugins

• Spring Security Core Plugin
• Resources Plugin
• Database Migration
• Fields
• Joda Time
• Twitter Bootstrap
• Country Selector

Back to the Start...

... is hiring !!!

Thank you ...

References