An overview of what DataMapper can do and where it will go in the future

1. Dirkjan Bussink
http://github.com/dbussink
http://twitter.com/dbussink

3. ORM?

4. DataMapper 0.10 is Released
DataMapper 0.10 is ready for release. We’ve worked on it
for the past 11 months, pushed 1250 commits, written
3000+ specs, and fixed 140 tickets in the process.

5. 1.8
1.9
JRuby
Windows *
* Sorry, no Windows / 1.9 yet...

7. Dan Kubb

8. DataMapper 101

9. class Person
include DataMapper::Resource
property :id, Serial
property :name, String
property :age, Integer
end

10. DataMapper.auto_migrate!
DataMapper.auto_upgrade!

12. class Person
...
property :name, String, :length => 512
...
end

13. Person.all(:name.like => "%me%")
Ruby!

14. repository do
puts Person.get(1).object_id => 2232427080
puts Person.get(1).object_id => 2232427080
end
Identity Map

16. Pluggable
Identity Map

17. http://www.flickr.com/photos/mattimattila

18. people = Person.all(:name.like => "%me%")
~ Query log empty...
p people
~ SELECT "id", "name" FROM people

19. :each
Kicker

20. people = Person.all
people.each do |person|
p person.addresses
end
SELECT "id", "name" FROM people;
SELECT "id", "street" FROM addresses WHERE ("person_id" IN (1,2,3))
Eager loading

21. RDBMS
IMAP
YAML

22. DataMapper.setup(:repo1, "postgres://postgres@localhost/dm")
DataMapper.setup(:repo2, "mysql://root@localhost/dm")
repository(:repo1) do
p Person.get(1) => #<Person @id=1 @name="Dirkjan" @age=27>
end
repository(:repo2) do
p Person.get(1) => #<Person @id=1 @name="Dan" @age=35>
end
Multiple repositories

23. DataMapper.setup(:repo1, "postgres://postgres@localhost/dm")
DataMapper.setup(:repo2, "mysql://root@localhost/dm")
get "/" do
# Odd / even sharding
repo = "repo#{user.id % 2 + 1}".to_sym
repository(repo) do
@people = Person.all
end
erb :people
end
Simple sharding

24. module DataMapper
module Adapters
class MyStorageAdapter < AbstractAdapter
def create(resources)
end
def read(query)
end
def update(attributes, collection)
end
def delete(collection)
end
end
end
end

25. Person.all(:name.like => 'dirk%').update!(:age => 28)
Person.all.destroy!(:age.gte => 100)
Bulk updates

26. When simple
querying is
not enough

27. Person.all(Person.addresses.street.like => "%street%")
SELECT "people"."id", "people"."name", "people"."age" FROM "people"
INNER JOIN "addresses" ON "people"."id" = "addresses"."person_id"
WHERE "addresses"."street" LIKE '%street%'
GROUP BY "people"."id", "people"."name", "people"."age"
ORDER BY "people"."id"
Complex querying!

28. class Person
include DataMapper::Resource
property :id, Serial
property :name, String
property :age, Integer
has n, :addresses
def self.named_like_me
all(:name.like => "%me%")
end
def self.older_than_me
all(:age.gt => 27)
end
end
Person.named_like_me.older_than_me
~ SELECT "id", "name", "age" FROM "people"
WHERE ("name" LIKE '%me%' AND "age" > 27) ORDER BY "id"
Query chaining

29. class Person
s
include DataMapper::Resource
e
property :id, Serial
p
property :name, String
o y
property :age, Integer
c b
s u
has n, :addresses
d R
def self.named_like_me
e
all(:name.like => "%me%")
end
m in
a la
def self.older_than_me
all(:age.gt => 27)
N p
end
end
i n
Person.named_like_me.older_than_me
~ SELECT "id", "name", "age" FROM "people"
WHERE ("name" LIKE '%me%' AND "age" > 27) ORDER BY "id"
Query chaining

30. Person.all(:name.like => '%me%').addresses.all(:street.not => nil)
SELECT "id", "street", "person_id" FROM "addresses"
WHERE (
"person_id" IN (SELECT "id" FROM "people" WHERE "name" LIKE '%me%')
AND "street" IS NOT NULL
) ORDER BY "id"
Subqueries

32. Person.all - Person.all(:name => 'Dan Kubb')
SELECT * FROM people WHERE NOT(name = 'Dan Kubb')

33. [1, 2] & [2, 3] == [2]
[1, 2] | [2, 3] == [1, 2, 3]

34. Plugins

35. class Person
...
property :name, String, :nullable => false
end
CREATE TABLE "people" ("id" SERIAL NOT NULL,
"name" VARCHAR(50) NOT NULL,
"age" INTEGER, PRIMARY KEY("id"))
Automatic Validations

36. Person.create
DataObjects::IntegrityError: ERROR:
null value in column "name" violates not-null constraint

37. person = Person.create
p person.errors => #<DataMapper::Validate::ValidationErrors:0x101d217a0
@errors={:name=>["Name must not be blank"]},
@resource=#<Person @id=nil @name=nil @age=nil>>

38. class Person
...
validates_present :name
end
Validations

39. class Person
...
property :created_at, DateTime
property :updated_at, DateTime
end
Timestamps

40. Person.all.adjust!(:age => 1)
Adjustments

41. class Person
...
has n, :addresses, :constraint => :destroy!
end
ALTER TABLE addresses
ADD CONSTRAINT addresses_person_id_fk
FOREIGN KEY (person_id)
REFERENCES people
ON DELETE CASCADE
ON UPDATE CASCADE
Constraints

42. module DataMapper
module Types
class IPAddress < DataMapper::Type
primitive String
length 16
def self.load(value, property)
IPAddr.new(value)
end
def self.dump(value, property)
value.to_s
end
def self.typecast(value, property)
value.kind_of?(IPAddr) ? value : load(value, property)
end
end
end
end
class NetworkNode
...
property :ipaddress, IPAddress
end
Custom types

44. class Address
include DataMapper::EmbeddedValue
property :street, String
end
class Person
include DataMapper::Resource
property :id, Serial
property :name, String
has n, :addresses
end

45. User.select { |u| u.id == 1 && u.name == 'Dan Kubb' }
Ambition style queries

46. http://www.flickr.com/photos/zoomar

47. http://datamapper.org/
http://github.com/datamapper
http://groups.google.com/group/datamapper
irc://irc.freenode.net/#datamapper

48. Questions?