datamapper l orm dans rails 3

DataMapper, l’ORM dans Rails 3 ?


Cyril Mougel

07 Mars 2009


DataMapper c’est quoi ?

1 DataMapper c’est quoi ?

2 Les base de DataMapper

3 Les plugins DataMapper




Commence en Fevrier 2007

Objet Relationel Model (Model Object Relationnel)

Supporte uniquement par la communaute



Pourquoi DataMapper ?

L’identity Map

La gestion des multi-repository natif

Lazy loading

Eager loading

Tout est ruby

Modulaire



Identity Map

User.first == User.first

User.first == User.get(1)



Gestion des multi-repository natif

User.all(:repository => :other)

User.all #:repository => :default



Lazy Loading

1 c l a s s Animal

2 include DataMapper : : Resource3 property : id , Serial

4 property : name , String #: l a z y => f a l s e5 property : notes , Text #: l a z y => t r u e6 end78 animals = Animal . all # No r e qu e s t9 animals . each do | pet | # SELECT id , name FROM Animals

10 pet . notes # SELECT note s FROM Animals WHERE i d = x11 pet . name # No more r e q u e s t12 end



Eager Loading

1 zoos = Zoo . all2 zoos . each do | zoo |3 # SELECT ’ i d ’ , ’ name ’ FROM Zoos4 # 1 ,3 ,5 , 6 , e t c . . .56 zoo . exhibits . each do | exhibit |7 # Fa i t un r equ e t e par i t e r a t i o n :8 # S e l e c t ’ name ’ from e x h i b i t s where z o o i d IN (1 , 3 , 5 , 6 ,

e t c . . . )9 puts ”Zoo : #{zoo . name} , E x h i b i t : #{ e x h i b i t . name}”

10 end11 end


Les base de DataMapper






Un classe Model

Herite seulement de Object

Include de include DataMapper::Resource

Les proprietes declare dans les classes modeles



1 class User2 include DataMapper :: Resource34 property :id, Serial5 property :name , String6 property :age , Integer78 has :n, :projects9 belongs_to :group

10 end



La recherche avec DataMapper

1 Zoo.first(:name.eql => ’Galveston ’)2 Person.all(:age.gt => 30)3 Person.all(:age.gte => 30)4 Person.all(:name.not => ’bob’)5 Person.all(:name.like => ’S%’, :id => [1, 2, 3,

4, 5])6 Person.all(:name.not => [’bob’,’rick’,’steve’])7 Person.all(: order => [:age.desc])


Les plugins DataMapper






dm-validations

validates xxxvalidation dans les properties directement

1 require ’dm−v a l i d a t i o n s ’23 c l a s s Account

4 include DataMapper : : Resource56 property : name , String

7 property : content , Text , : length => ( 1 0 0 . . 5 0 0 )8 property : email , String , : nullable => f a l s e , : unique =>

t rue , : format => : email_address ,9 : messages => {

10 : presence => ”need ema i l ” ,11 : is_unique => ” a l r e a d y used ” ,12 : format => ” not a ema i l ”13 }1415 validates_length : name , : max => 201617 end



dm-migrations

1 migration 1 , : create_orders do2 up do3 create_table ( : orders ) do4 column ( : id , Integer , : serial => t r u e )5 column ( : amount , Integer )6 column ( : completed , Boolean )7 column ( : description , String , : size => 255)8 column ( : created_at , DateTime )9 column ( : updated_at , DateTime )

10 end11 end1213 down do14 drop_table ( : orders )15 end16 end



plein d’autre plugins

dm-types

dm-timestamp

dm-tags

dm-sweatshop

dm-constraints

dm-is-list

etc..



Les ressources ?

http ://datamapper.org

http ://github.com/datamapper

http ://groups.google.com/group/datamapper



questions ?