Building an ORM with Arel

This talk was presented at RubyConf Brasil 2014 with @vipulnsward

Transcript

1. Olá
2. Building an ORM with ARel Walking up the AS(Tree) @vipulnsward, @_cha1tanya
3. Vipul @vipulnsward && Prathamesh @_cha1tanya
7. RubyIndia.org
9. podcast.rubyindia.org
10. Indian Ruby Conferences RubyConfIndia Garden City Ruby Conf DeccanRubyConf Do visit India!
11. Building an ORM with ARel Walking up the (AS)Tree @vipulnsward, @_cha1tanya
14. Build our own ORM - Why?
15. Object-relational mapping (ORM, O/RM, and O/R mapping) in computer science is a programming technique for converting data between incompatible type systems in object- oriented programming languages. This creates, in effect, a "virtual object database" that can be used from within the programming language.
16. Active Record “An object that wraps a row in a database table or view, encapsulates the database access, and adds domain logic on that data.”
17. Components • Database connection • Query Generator • Attribute Access • Typecasting
18. SQL torm_development=# select * from posts; id | name | content | author | subject -----+-------------+---------+------------+--------- 332 | RGenGC| Restricted Generation Garbage Collection | GorbyPuff | How does RGenGC work? (1 row)
19. Object Post: id: 332, name: ‘RGenGC’, subject: ‘How does RGenGC work?’ content: ‘Restricted Generation Garbage Collection’ author: ‘GorbyPuff’
20. Object Post: id(int): 332, name(string): ‘RGenGC’, subject(string): ‘How does RGenGC work?’ content(string): ‘Restricted Generation Garbage Collection’ author(string): ‘GorbyPuff’
21. What? post = Post.new subject: 'What is RGenCG?' post.save first_post = Post.find(1) puts first_post.subject #=> 'What is RGenCG?'
22. How? class Post < Torm::Model … end
23. Role of ARel
24. ARel • Relational Algebra for Ruby • ARel is a SQL AST manager for Ruby • Can generate complex SQL queries • Adapts to multiple databases
25. ARel Components • AST • Visitors • Managers
26. ORM Database ARel
27. Engine • Provide information to ARel/ Attributes Access • Column / Table structure • Database Adapter • Data Type Mappings
28. Engine Skeleton
29. Database Connection
30. Columns
31. Schema Cache
33. Tests
35. Attributes • Data Types • Casting from / to database types • Attribute Maps for table • Accessors for a model
36. Types • Types • TypeMap • Attribute • AttributeSet
37. Attribute Accessors • Readers • Writes • Initializer
38. Database Statements • create • update • save • destroy
39. Querying • find • count • where • delete_all • ...
40. Summary • Database Connection • Creating columns/ Schema cache • Attribute Types/ Type casting • Attributes and accessors • Database statements • Querying
41. Other • Associations • Migrations • Callbacks • Validations • ...
42. Obrigado! gh: prathamesh-sonpatki/torm @vipulnsward @_cha1tanya