Groovy et Grails

Julien Marcil

julien@marcil.com - @Nr9

Groovy

• is an agile and dynamic language for the Java Virtual Machine.
• builds upon the strengths of Java but has additional power features inspired by languages like Python, Ruby and Smalltalk.
• makes modern programming features available to Java developers with almost-zero learning curve.
• supports Domain-Specific Languages and other compact syntax so your code becomes easy to read and maintain.

Un programme Java typique

public class HelloWorld {
    private String name;

    public void setName(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public String greet() {
        return "Hello " + name;
    }
    
    public static void main(String[] args) {
        HelloWorld helloWorld = new HelloWorld();
        helloWorld.setName("Groovy");
        System.out.println( helloWorld.greet() );
    }
}
					

Un programme Groovy valide

public class HelloWorld {
    private String name;

    public void setName(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public String greet() {
        return "Hello " + name;
    }
    
    public static void main(String[] args) {
        HelloWorld helloWorld = new HelloWorld();
        helloWorld.setName("Groovy");
        System.out.println( helloWorld.greet() );
    }
}
					

Interopérabilité complète

Type dynamique

		
def v = 3
v = 'avion'
v = false
v = new StringBuffer()
v = null
					

Closure

		
def f = { list, value -> list << value }
x = []
f(x, 1)
f(x, 2)
f(x, 3)
assert x == [1, 2, 3]
					

Grails

• Groovy Web Application Framework.
• inpired by Dynamic Frameworks like Rails, Django and TurboGears.
• based on the Don't Repeat Yourself (DRY) principle.
• Convention over Configuration.

Basé sur les meilleurs frameworks Java

• Spring Framework
  • Spring MVC
  • Spring Transaction
  • Spring MessageSource (i18n)
• Hibenate
• SiteMesh
• embedded Tomcat

Structure

Domain Classes

		
class Author {
    static hasMany = [books: Book]
    String name
}
					

		
class Book {
    static belongsTo = [author: Author]
    String title
}
					

Domain Classes

		
class Book {
    static belongsTo = [author: Author]

    String title
    Date releaseDate
    String ISBN
    BigDecimal price

    static constraints = {
        title(blank: false, maxSize:100)
        isbn(blank: false, matches:"[0-9]13" minSize:13 maxSize:13, unique: true)
        price(nullable: true, min: 0.0, max: 9999.99, scale: 2)
    }

    static mapping = {
        table "books"
        price column: "sales_price"
    }

    def beforeInsert() { dateCreated = new Date() }
}
					

CRUD

	
// Create	
def a = new Author(name: "King")
a.save()
					

		
// Read	
def a = Author.get(1);
					

		
// Update	
def a = Author.get(1);
a.name = "Stephen King"
a.save()
					

		
// Delete	
def a = Author.get(1);
a.delete()
					

Dynamic Finder

		
Book.findByTitle("The Stand")

Book.findByTitleLike("Harry Pot%")

Book.findByReleaseDateBetween(firstDate, secondDate)

Book.findByReleaseDateGreaterThan(someDate)

Book.findByTitleLikeOrReleaseDateLessThan("%Something%", someDate)
					

Where Queries

		
def query = Person.where {
   firstName == "Julien"
}
Person julien = query.find()
					

		
def children = Book.findAll { age in 0..17 }
					

Critera

		
def criteria = Account.withCriteria {
    between("balance", 500, 1000)
    eq("branch", "London")
    or {
        like("holderFirstName", "Fred%")
        like("holderFirstName", "Barney%")
    }
    maxResults(10)
    order("holderLastName", "desc")
}
					

Services

		
class BookService {

    static transactional = true
    static scope = "singleton" //prototype, request, flash, 
                               //conversation, session, singleton

    def authorService // the AuthorService will be injected

    def updateSomething() {
         // Business Logic
    }

    @Transactional(readOnly = true)
    def listBooks() {
        Book.list()
    }
}
					

Controllers

		
class BookController {
    def list() {
        def map = [books: Book.list(params), total: Book.count()]
        render(view: "books", model: map)
    }

    def show() {
        [book: Book.get(params.id)]
    }
}
					

Controllers

		
class BookController {
    def json()
    {
        render Book.list(params) as JSON
    }

    def xml()
    {
        render Book.list(params) as XML
    }
}
					

GSP

		
<!DOCTYPE html>
<html>
    <head>
        <title>${book?.title}</title>
        <r:require module="jquery"/>
        <r:layoutResources/>
    </head>
    <body>
        

            
Title: ${book?.title}
            
Author: ${book?.author?.name}
        
        <r:layoutResources/>
    </body>
</html>					
					

URL Mapping

		
class UrlMappings {

    static mappings = {
        "/$controller/$action?/$id?"{
            constraints {
                // apply constraints here
            }
        }

        "/"(view:"/index")
        "500"(view:'/error')
        "404"(view:'/404')
    }
}
					

Plugins

Démo!

Question?

Merci!