GA | Rails | ActiveRecord

Intro to Ruby On Rails Active Record, including: ORM (Object-Relational Mapping), Validations, CRUD, Associations...

Transcript

1. Fer Martin Web Development Immersive Instructor ACTIVE RECORD
2. HTTP://GUIDES.RUBYONRAILS.ORG 2 DISCLAIMER THE ENTIRE CONTENT OF THIS PRESENTATION CAN BE FOUND AT:
3. ACTIVE RECORD
4. LEARNING GOALS 4 How Active Record fits into the Model-View-Controller paradigm. What Object Relational Mapping and Active Record are and how they are used in Rails. How to use Active Record models to manipulate data stored in a relational database. Active Record schema naming conventions.Active Record schema naming conventions. The concepts of database migrations, validations and callbacks.
5. WHAT IS ACTIVE RECORD? ACTIVE RECORD IS THE M IN MVC - THE MODEL ! - RESPONSIBLE FOR REPRESENTING: * BUSINESS DATA * LOGIC - FACILITATES THE CREATION AND USE OF BUSINESS OBJECTS - DATA PERSISTED TO A DATABASE 5
6. WHAT IS ACTIVE RECORD? ACTIVE RECORD DESIGN PATTERN ! HTTP://EN.WIKIPEDIA.ORG/WIKI/ACTIVE_RECORD_PATTERN 6
7. ORM OBJECT-RELATIONAL MAPPING CONNECTS: 7 class Person - legs:string ! - walk() table People - legs:text(255) OBJECTS * WRITING SQL STATEMENTS DIRECTLY IS NOT REQUIRED * HTTP://EN.WIKIPEDIA.ORG/WIKI/LIST_OF_OBJECT-RELATIONAL_MAPPING_SOFTWARE RELATIONAL DATABASE MANAGEMENT SYSTEM
8. ACTIVE RECORD AS AN ORM FRAMEWORK - REPRESENTS * MODELS AND THEIR DATA. * ASSOCIATIONS BETWEEN THESE MODELS * INHERITANCE HIERARCHIES THROUGH RELATED ! - VALIDATE MODELS BEFORE THEY GET PERSISTED TO THE DB ! - PERFORM DB OPERATIONS IN AN OBJECT-ORIENTED FASHION 8
9. CONVENTION OVER CONFIGURATION
10. FIRST ATTEMPTS OF HUMAN KIND TO WRITE ORMS… 10
11. NAMING CONVENTIONS GOAL: EASILY MAP 11 class Person - legs:string ! - walk() table People - legs:text(255) MODELS (CLASSES) TABLES (DATABASE) TO
12. NAMING CONVENTIONS 12 RAILS DATABASE
13. SCHEMA CONVENTIONS DATABASE COLUMN NAMES PRIMARY KEYS: ID (INTEGER) ! ! FOREIGN KEYS: SINGULARIZED_TABLE_NAME_ID (INTEGER) 13 EXAMPLES: PERSON_ID | ITEM_ID | ORDER_ID | BOOK_ID * CREATED AUTOMATICALLY BY ACTIVE RECORD WHEN USING MIGRATIONS
14. SCHEMA CONVENTIONS: EXTRAS ACTIVE RECORD WILL ALSO INCLUDES, BY DEFAULT ! - CREATED_AT (DATETIME) ! - UPDATED_AT (DATETIME) 14
15. CREATING ACTIVE RECORD MODELS
16. CREATING A MODEL IS CREATING A CLASS APP/MODELS/PRODUCT.RB 16
17. ACTIVE RECORD :: BASE GITHUB.COM/RAILS/RAILS/BLOB/MASTER/ ACTIVERECORD/LIB/ACTIVE_RECORD/BASE.RB 17
18. AUTOMATIC ATTRIBUTE ACCESS 18
19. C REATE R EAD U PDATE D ELETE
20. CREATE | RETURNS A NEW OBJECT | SAVES OBJECT TO DATABASE CREATE VS NEW 20 NEW | RETURNS A NEW OBJECT
21. READ 21 ACTIVERECORD::QUERYING#METHODS
22. READ 22 MODEL.ALL | RETURNS A COLLECTION OF ALL THE OBJECTS MODEL.FIRST | RETURNS THE OBJECT WITH LOWEST “ID” MODEL.LAST | RETURNS THE OBJECT WITH HIGHEST “ID”
23. UPDATE | UPDATES A SINGLE OBJECT UPDATE 23 FIND & SAVE | FINDS THE OBJECT, UPDATE ATTRIBUTES, SAVE UPDATE_ALL | UPDATES ALL OBJECTS AT ONCE
24. DESTROY_ALL | DELETES ALL OBJECTS GIVEN A CONDITION DELETE 24 FIND & DESTROY | FINDS THE OBJECT, DESTROY IT
25. VALIDATIONS
26. VALIDATIONS 26 VALID? | CHECK ALL VALIDATIONS http://apidock.com/rails/ActiveRecord/Validations/valid%3F
27. CREATE! | TRY TO CREATE, RAISE EXCEPTION IF CAN’T CREATE VS CREATE! 27 CREATE | TRY TO CREATE, RETURN FALSE IF CAN’T
28. BANG BANG BANG 28 CREATE | TRY TO CREATE, RETURN FALSE IF CAN’T SAVE | TRY TO SAVE, RETURN FALSE IF CAN’T UPDATE | TRY TO UPDATE, RETURN FALSE IF CAN’T ! SAVE! | TRY TO SAVE, RAISE EXCEPTION IF CAN’T CREATE! | TRY TO CREATE, RAISE EXCEPTION IF CAN’T UPDATE! | TRY TO UPDATE, RAISE EXCEPTION IF CAN’T
29. VALIDATION HELPERS 29 PRESENCE | ENSURES THE FIELD IS NOT EMPTY
30. VALIDATION HELPERS 30 UNIQUENESS | ENSURES THE FIELD IS UNIQUE
31. VALIDATION HELPERS 31 NUMERICALITY | ENSURES THE FIELD CONTAINS ONLY NUMBERS USEFUL HELPERS
32. VALIDATION HELPER OPTIONS 32 :ALLOW_NIL | SKIPS VALIDATIONS IF VALUE IS NIL? ! :ALLOW_BLANK | SKIPS VALIDATIONS IF VALUE IS BLANK? ! :MESSAGE | CUSTOM-MADE ERROR MESSAGE ! :ON | WHEN DO YOU WANT TO RUN THE VALIDATIONS | :CREATE | :UPDATE ! http://guides.rubyonrails.org/active_record_validations.html#validation-helpers
33. VALIDATIONS ERROR HANDLING
34. VALIDATION ERROSR HANDLING 34 MODEL.ERRORS.MESSAGES ! ! ! http://guides.rubyonrails.org/active_record_validations.html#working-with-validation-errors
35. VALIDATION ERROSR DISPLAY IN THE VIEW 35 MODEL.ERRORS.ANY? MODEL.ERRORS.COUNT MODEL.ERRORS.FULL_MESSAGES ! http://guides.rubyonrails.org/active_record_validations.html#displaying-validation-errors-in-views
36. VALIDATION ERROSR DISPLAY IN THE VIEW 36
37. ACTIVERECORD ASSOCIATIONS
38. WHAT ARE ASSOCIATIONS ASSOCIATIONS ALLOW US TO LINK MODELS ! 38 http://en.wikipedia.org/wiki/Relational_database http://en.wikipedia.org/wiki/Relation_(database)
39. MODEL ASSOCIATIONS 39 http://guides.rubyonrails.org/association_basics.html
40. ACCESS ASSOCIATED MODELS 40
41. TYPE OF ASSOCIATIONS WE DEFINE THE TYPES OF ASSOCIATIONS IN THE MODELS ! - BELONGS_TO - HAS_ONE - HAS_MANY ! ADVANCED - HAS_ONE :THROUGH - HAS_MANY :THROUGH - HAS_AND_BELONGS_TO_MANY 41 http://en.wikipedia.org/wiki/Relational_database http://en.wikipedia.org/wiki/Relation_(database)
42. NAMING CONVENTIONS 42 RAILS DATABASE class Order belongs_to :customer table orders customer_id class Customer has_many :orders table customers ? …..
43. MODEL ASSOCIATIONS NEED MIGRATIONS! 43
44. HAS_ONE :SOMETHING 44
45. WHO HAS_ONE :SOMETHING? 45 SUPPLIER HAS_ONE ACCOUNT VS ACCOUNT HAS SUPPLIER !
46. HAS_MANY :SOMETHINGS 46
47. BI-DIRECTIONAL ASSOCIATIONS 47
48. 48 DISCLAIMER FIND MANY MORE AWESOME GUIDES
49. 49 DISCLAIMER
50. THANK YOU!!
51. THE END