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Grails
- 2. Groovy & Grails Alex Staveley
- 3. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 • Groovy – 2003 (1.0 2007) – Dynamic Language (Ruby, Python) (Expressive, Ceremony, syntactic sugar) – JVM – JStack, JPM, javap, jconsole • Grails – Web Framework Page 3 Groovy & Grails - History
- 4. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 4 History
- 5. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 5 Start with Groovy …
- 6. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 6 Start with Groovy (cont.)
- 7. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 7 Start with Groovy (cont.)
- 8. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 8 Start with Groovy (cont.)
- 9. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 String country = country.name ?: “Unknown Country” String location = map ?.getLocation()?.getCoordinates() [‘Denver’, ‘Paris’, ‘Nice’, ‘Lima’]*.toUpperCase() // sendRequest(QkrUser.&create) … sendRequest(MethodClosure method) { … method(“new user”) Page 9 Fancy operators
- 10. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 10 Express a regular expression
- 11. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 [[sku:12, name:’walmart’], [sku:78, name:’walmart’], [sku:54, name:’walmart’], [sku:88, name:’saks’],[sku:33, name:’saks’]] [walmart: [12, 78, 54], saks: [88, 33]] Map productSkusPerMerchant = skuMerchantPairs.groupBy{it.merchantName}.collectEntries{k, v -> [(k): v*.sku]} Page 11 Very fancy collection stuff
- 12. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 12 Fancy other stuff
- 13. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 13 Fancy String Stuff
- 14. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 String message = “Dublin is better than most places” println “First Character: ${message[0]}” // D println “Last character: ${message[-1]}” //s // sub-string println message[0..5] // Dublin println message[5..0] // nilbuD Page 14 More fancy stuff
- 15. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 def “Test findPositives” () { given: “A bunch of people” def service = new NumberService() when: “I pass in a list of numbers” def result = service.findPositives(numbers) then: “Only positive numbers returned” result == expected where: number | expected null | [] [-1, 4, 5] | [4, 5] Page 15 Really good testing opportunities – even for Java projects
- 16. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 16 Closures
- 17. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 17 Closure - JavaScript
- 18. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 18 Closures
- 19. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 19 Closures – Execute Around Pattern
- 20. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 20 Execute and Around Pattern cont.
- 21. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 21 Meta Programming
- 22. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 • @Immutable • @TypeChecked • @GrailsTypeChecked • @CompileStatic - slow groovy code. • @Delegate Page 22 AST Transformations
- 23. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 23 @Delegate
- 24. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 24 AST Transformation write your own
- 25. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 25 AST Transaction, write your own
- 26. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 26 CartItem with Updated annotation
- 27. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 27 Great JSON / XML support
- 28. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 28 Great XML support cont.
- 29. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 29 JSON Support
- 30. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 trades = { buy 500 of ryanair sell 300 of microsoft buy 100 of google } trades = { buy(500).of(ryanair) sell(300).of(microsoft) buy(100).of(google) } Page 30 DSL
- 31. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 - Rapid Web Application Dev Framwork - First Class Java Integration - Inspired by Ruby on Rails, Django - Convention over configuration - Leverages Java technologies Spring, Hibernate - Spring MVC under the hood - Service container - Full stack - Build in DB Page 31 Grails
- 32. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 • grails –version • grails create-app MyApp • grails run-app • grails console – Very useful for understanding GORM, consequences etc. Page 32 Grails command line
- 33. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 33 Grails – Convention over Configuration
- 34. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 34 Grails Configuration – really good
- 35. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 35 Grails - BuildConfig
- 36. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 36 Grails - Plugins
- 37. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 • Hibernate, Mongo, Redis etc • Put in the domain package and you get 20 instance methods and over 70 static methods • Instance: delete(), save(), validate(), refresh() • Static: count(), find(), findAll(), first(), last() – Note methods such as findByNameI) etc are synthesised code • Build in constraints: creditCard, email, unique (executes a query string during validation), Page 37 Grails - GORM
- 38. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 Page 38 GORM Example
- 39. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 • How good is your schema? • Saves can silently fail (failOnError) • Saves happen in the “Hession”. Hibernate decides when they get fired to DB and in what order (flush is false by default) • Changes to objects attached to the session persist, without a call to save • Cascading saves / deletes can take a bit of time to get right. • N + 1 problem • Just enable hibernate logging Page 39 GORM Gotcha’s
- 40. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 • Perl, Python not on the JVM • Bash – remember, forget, can be difficult to read. • Anywhere the JVM is, you can run the script. • Define classes in your script • @Grab annotation to get dependencies from maven central • Run easily from command line A great use case for Grails / Groovy Page 40 Grails – Scripts
- 41. ©2014 MasterCard. Proprietary and Confidential October 30, 2014 • Basics – any Java programmer. Experience of Python, JavaScript, even Scala etc. helps • Best practises – ShopThis! • Code reviews Page 41 How do we learn it?
- 42. © Copyright – Internal Use Only
Editor's Notes
- Grails 2.4 – Java 8, Spring 4.0, Hibernate 4.2, @GrailsCompileStatic Groovy 2.3 – Traits, Grails 3.0 – Hadoop, Netty, Spring Boot, More support micro architectures, gradle,
- groupBy gives: [walmart: [[sku: 12, name: walmart], [sku:78,name: walmart], [sku:54, name:’walmart’]], saks: [[sku: 88, name: saks], [sku: 33, name: saks]]
- - Can use this approach for a Java project by adding a groovy and spock jar. Spock converts it to a Junit under the hood.
- Smalltalk
- Remember your audiences, traders or progammers Trades is a closure and if you can see the delegate of a closure. So you can set the closure of trades to something that implements buy, sell. Buy() and sell() can return something that implements of. But how does ryanair, microsoft etc get set to be a string?? The Delegate, like every Groovy object has a method called: Object getProperty(String name), implement it to just return name. But don’t forget error handling?
- All part of the build system Can pass arguments
- N + 1 problem: