Virtus

Transcript

1. News!!!
2. Rails Rumble 2013 http://railsrumble.com/ Signup ends Oct. 13th
3. http://gotocon.com/berlin-2013/
4. URM
5. Unsung Rubyist of the Month
6. http://www.ruby-mine.de/wonado http://www.ruby-mine.de/regexp
7. Virtus
8. DataMapper: The Awesome Parts
9. This is a partial extraction of the DataMapper Property API with various modifications and im- provements. The goal is to provide a common API for defining attributes on a model...
10. The README covers (almost) all, so I am not iterating through the examples.
11. class User include Virtus.model attribute :name, String attribute :age, Integer attribute :birthday, Date attribute :registered, Time, :default =>->() { Time.now } end
12. json = '{"name": "Florian Gilcher", "age": 30, "birthday": "October 4th, 1983"}' parsed = JSON.parse(json) user = User.new(parsed) #=> #<User:0x000001008d8b68 @age=30, @birthday= #<DateTime: 1983-10-04T...>, @name="Florian Gilcher", @registered="....">
13. module Named include Virtus.module attribute :name, String end class User include Named end u = User.new u.attributes = {:name => "Florian Gilcher"}
14. class Location include Virtus.value_object values do attribute :lat, BigDecimal attribute :lon, BigDecimal end end Location.new(:lat => 1, :lon => 1) == Location.new(:lat => 1, :lon => 1)
15. All this actually consisted of 3 parts: • coercion • constructor • mass assignment
16. class User include Virtus.model( :constructor => false, :mass_assignment => false ) attribute :name, String attribute :age, Integer attribute :birthday, DateTime end
17. class User include Virtus.model(:coerce => false) attribute :name, String attribute :age, Integer attribute :birthday, DateTime end u = User.new u.age = "123" u.age #=> "123"
18. class Named include Virtus.module(:coerce => false) attribute :name, String end
19. class ShowOff attribute :users, Set[User] attribute :tags, Array[String] attribute :meta, Hash[Symbol => String], :coerce => false attribute :i_dont_know_what_this_is_good_for, Hash[String => Hash[String => User]] end
20. What is this good for?
21. Object graph prototyping
22. ActiveRecord::serialize
23. class User < ActiveRecord::Base serialize :preferences end User.new(:name => "fgilcher", :preferences => { :columns => 3, :scheme => "dark"} })
24. class User < ActiveRecord::Base serialize :preferences end User.new(:name => "fgilcher", :preferences => { :columns => 3, :scheme => "dark"} })
25. class Preferences include Virtus.model attribute :columns, Fixnum, :default => 2 attribute :scheme, String end class User < ActiveRecord::Base serialize :preferences, Preferences end
26. pref = Preferences.new(:columns => 2, :scheme => "dark") User.create(:name => "fgilcher", :preferences => pref) User.first #=> #<User id: 1, name: "fgilcher", preferences: #<Preferences...>>
27. Or any other store storing complex values (NoSQL)
28. Form objects
29. require 'active_model' class Preferences include ActiveModel::Validations validates_presence_of :columns, :scheme end
30. Consider using Virtus every time you would use OpenStruct or Hash in anger!
31. Handling attributes
32. att = Preferences.attribute_set[:columns] att.name #=> :columns att.coerce("2") #=> 2 att.default_value.value #=> 2
33. hash.each do |k,v| setter_name = "#{k}=" object.send(setter_name, v) end
34. att.get(pref) #=> 2 att.set(pref, 3) #=> 3
35. Finally, a proper attribute setting API on all objects!
36. Final words
37. Virtus comes at a small cost, so it should be used for domain models only.
38. This cost does JIT away very well in most cases.
39. Virtus shines through what it doesn’t do, not through what it does.