"Lessons Learned Teaching a Groovy/Grails Course" from GR8conf EU 2015

1. LESSONS LEARNED TEACHING A
GROOVY/GRAILS COURSE
Jacob Aae Mikkelsen

2. AGENDA
Course description
The Students
Example questions
Results
Reflections

3. JACOB AAE MIKKELSEN
Senior Engineer at Lego
Microservice based architechture on JVM
Previously 4 years at Gennemtænkt IT
Consultant on Groovy and Grails
External Associate Professor - University of Southern
Denmark
@JacobAae
Blogs The Grails Diary

4. DM844 - WEB DEVELOPMENT WITH
GROOVY AND GRAILS

5. THE PRACTICAL INFO
University level (3rd & 4th year)
Full-stack Course
42 Students
2 * 2 hours teaching each week

6. GOAL
To bridge the gap between the theoretical academic
world and the outside practical world

Practical project
4 parts
14 groups of 3 student
Same proposal → 14 very different results

7. TECHNOLOGIES

8. EVALUATION
Group project
Written report
Oral exam

9. FORMAL EVALUATION GOALS (1)
Design an application in an MVC web framework,
including the separation of logic and presentation
Apply and demonstrate the use of tools for static code
analysis
Apply and demonstrate the use of tools for test coverage
Evaluate and comment on code quality, for example. by
code review
Use version control and semantic versioning with a group
of other developers

10. FORMAL EVALUATION GOALS (2)
Analyze and test the security in web applications
Configure a cloud based hosting server for a
webapplikation with database access
Use continous integration and automate the proces of
testing and deploying
Implement the designed webapplication, with support for
multiple languages, responsive design and asynchronous
updates (one-page-app)

11. THE STUDENTS

12. CHARACTERISTICS
75% Computer Science
25% Software Engineering

13. CHARACTERISTICS
Great with algorithms, complexity etc
Not used to focus on code quality and testing
Not used to configuring servers
Never used CI

14. SNIPPETS
String toString() {
return this.firstName+" "+this.lastName
}

15. SNIPPETS
class SalaryServiceSpec extends Specification {
def setup() {
}
def cleanup() {
}
void "test something"() {
}
}

16. SNIPPETS
def createNewProject(params) {
def projectOwner = ProjectOwner.get(params.projectOwnerID)
def project = new Project(title:params.projectTitle,
shortDescription: params.projectShortDesc,
description: params.projectDesc, projectOwner:projectOwner
)
project.save(failOnError: true)
projectOwner.addToProjects(project)
}

17. SNIPPETS
def findProjectRequest() {
ProductRequest theProject = ProductRequest.findById(theId)
return theProject
}

18. SNIPPETS
} else if(areaIn.bookings.getClass() == org.codehaus.groovy.runtime.NullObj

19. SNIPPETS
@Build(Area)
class AreaUnitSpec extends Specification{
void "Show build method"(){
setup:
Area.build(name: 'Pitch One')
when:
Area area = Area.findByName('Pitch One')
then:
area
area.name == 'Pitch One'
}
}

20. EXAMPLE QUESTIONS
Lets look at a few of the questions I received during the
course

21. PERFORMANCE ISSUE
Browser hangs on create on some of the classes
when using scaffolded views


22. PERFORMANCE ISSUE
class Patient {
Integer patId
String name
String phone
String email
static constraints = {
name size: 2..255
email email: true
patId range: 1..100000, unique: true
phone size: 8..12, matches: "[0­9]+"
}
}

23. USING DATECREATED
We would like to use dateCreatedin validation, as
some of the dates cannot be set in the past (at
creation time)

Not set before it is saved - cannot use new Date()
on edit


24. DATA MODELLING WITH EMBEDDED
CLASSES
For a delivery company, we have a delivery having
two embedded delivery points each having an
embedded address. Gorm cannot handle this
(naming clash)


25. GEB TESTING
The Geb test fails because the bottom bar is on top of
the button

when: "we click next"
JavascriptExecutor executor = (JavascriptExecutor) driver
executor.executeScript("window.scrollBy(0,500)")
$("input", name: "Next").click()

26. RESULTS

27. PROJECT OUTCOME
Some of the results
https://crashh.me/dm844/
https://www.temporaria.me/
https://www.fmind.me
https://ss-software.dk/
https://www.pconnector.me/
https://clubadmin.dk

28. REFLECTIONS

29. FEEDBACK
Learned new stuff
Lots of waiting while compiling and running tests
Real work-life experience

30. UP’S
Dynamic scaffolding - and speed to get started
Great Project results
Engaging students (most of them)
Helpfull in Facebook Group
Wow-factors
GORM
AST transformations
Spock - where clause for testing

31. DOWN’S
Huge workload
Hard to compare different projects

32. RECOMMENDATIONS
Next iteration
Point to Github student pack
Use Grails 3
Fixating the project description

33. THANKS
Jetbrains for IntelliJ educational license for all students
Digital Ocean For vouchers for servers

34. REFERENCES
Course home page
Full course description

35. QUESTIONS?