Downloaded 31 times
![Implementation
class Task {
Inventory inventory
String description
static belongsTo = [Inventory]
static constraints = {
description(nullable: false, blank: false)
}
}
class Inventory {
String name
static hasMany = [tasks: Task]
static constraints = {
name(nullable: false, blank: false, unique: true)
}
}](https://image.slidesharecdn.com/grailspatternsandpractices-130726073609-phpapp02/85/Grails-patterns-and-practices-11-320.jpg)
![Domain Tests
class InventoryTests extends GrailsUnitTestCase {
void testConstraints() {
def existingInventory = new Inventory(name: "Paul’s Inventory")
mockForConstraintsTests(Inventory, [ existingInventory ])
! ! // Validation should fail if both properties are null.
! ! def inventory = new Inventory()
! ! assertFalse inventory.validate()
! ! assertEquals "nullable", inventory.errors["description"]
! ! // So let's demonstrate the unique constraint.
! ! inventory = new Inventory(name: "Paul’s Inventory")
! ! assertFalse inventory.validate()
! ! assertEquals "unique", inventory.errors["name"]
! ! // Validation should pass!
! ! inventory = new Inventory(name: "John’s Inventory")
! ! assertTrue inventory.validate()
! }
}](https://image.slidesharecdn.com/grailspatternsandpractices-130726073609-phpapp02/85/Grails-patterns-and-practices-12-320.jpg)
![RESTful URL Mappings
static mappings = {
"/task/$id?"(resource:"task")
}
static mappings = {
"/task/$id"(controller:"task") {
action = [GET:"show", PUT:"update", DELETE:"delete", POST:"save"]
}
}
static mappings = {
"/task/$id"(controller:"task", parseRequest:true) {
action = [GET:"show", PUT:"update", DELETE:"delete", POST:"save"]
}
}](https://image.slidesharecdn.com/grailspatternsandpractices-130726073609-phpapp02/85/Grails-patterns-and-practices-34-320.jpg)
![Layouts and Fragments
<g:include action="show" id="1" />
<g:include action="show" id="${currentTask.id}" />
<g:include controller="task" />
<g:include controller="task" action="list" />
<g:include action="list" params="[sort:'title', order:'asc'] />
<html>
<head>
<title><g:layoutTitle default="An example decorator" /></title>
<g:layoutHead />
</head>
<body>
<div class="menu"><!--my common menu goes here--></menu>
<div class="body">
<g:layoutBody />
</div>
</div>
</body>
</html>](https://image.slidesharecdn.com/grailspatternsandpractices-130726073609-phpapp02/85/Grails-patterns-and-practices-49-320.jpg)
![Implementation
class Task {
Inventory inventory
String description
static belongsTo = [Inventory]
static constraints = {
description(nullable: false, blank: false)
}
}
class Inventory {
String name
static hasMany = [tasks: Task]
static constraints = {
name(nullable: false, blank: false, unique: true)
}
}](https://image.slidesharecdn.com/grailspatternsandpractices-130726073609-phpapp02/75/Grails-patterns-and-practices-11-2048.jpg)
![Domain Tests
class InventoryTests extends GrailsUnitTestCase {
void testConstraints() {
def existingInventory = new Inventory(name: "Paul’s Inventory")
mockForConstraintsTests(Inventory, [ existingInventory ])
! ! // Validation should fail if both properties are null.
! ! def inventory = new Inventory()
! ! assertFalse inventory.validate()
! ! assertEquals "nullable", inventory.errors["description"]
! ! // So let's demonstrate the unique constraint.
! ! inventory = new Inventory(name: "Paul’s Inventory")
! ! assertFalse inventory.validate()
! ! assertEquals "unique", inventory.errors["name"]
! ! // Validation should pass!
! ! inventory = new Inventory(name: "John’s Inventory")
! ! assertTrue inventory.validate()
! }
}](https://image.slidesharecdn.com/grailspatternsandpractices-130726073609-phpapp02/75/Grails-patterns-and-practices-12-2048.jpg)
![RESTful URL Mappings
static mappings = {
"/task/$id?"(resource:"task")
}
static mappings = {
"/task/$id"(controller:"task") {
action = [GET:"show", PUT:"update", DELETE:"delete", POST:"save"]
}
}
static mappings = {
"/task/$id"(controller:"task", parseRequest:true) {
action = [GET:"show", PUT:"update", DELETE:"delete", POST:"save"]
}
}](https://image.slidesharecdn.com/grailspatternsandpractices-130726073609-phpapp02/75/Grails-patterns-and-practices-34-2048.jpg)
![Layouts and Fragments
<g:include action="show" id="1" />
<g:include action="show" id="${currentTask.id}" />
<g:include controller="task" />
<g:include controller="task" action="list" />
<g:include action="list" params="[sort:'title', order:'asc'] />
<html>
<head>
<title><g:layoutTitle default="An example decorator" /></title>
<g:layoutHead />
</head>
<body>
<div class="menu"><!--my common menu goes here--></menu>
<div class="body">
<g:layoutBody />
</div>
</div>
</body>
</html>](https://image.slidesharecdn.com/grailspatternsandpractices-130726073609-phpapp02/75/Grails-patterns-and-practices-49-2048.jpg)
More Related Content
Similar to Grails patterns and practices
Grails patterns and practices
- 1. Grails: Patterns & Practices PaulBowler Senior Consultant, OpenCredo
- 2.
- 3. Coding Dojo • Agile! •Teams of 2-4 people • 1 sprint = 20 minutes • Domain-Drive Design (I’m the Product Owner) • Test-Driven Development (Maybe!) • Yes, you can use the user guide and internet! • User demo at the end of each sprint • Discussion + Refactoring • Prize for best app!
- 4.
- 5. Domain-Driven Design • “Domain-drivendesign (DDD) is an approach to developing software for complex needs by deeply connecting the implementation to an evolving model of the core business concepts.” • The premise of domain-driven design is the following: • Placing the project's primary focus on the core domain and domain logic • Basing complex designs on a model • Initiating a creative collaboration between technical and domain experts to iteratively cut ever closer to the conceptual heart of the problem.
- 7. User Story 1 “Asa pomodoro fan, I would like to be able to add tasks to a uniquely named activity inventory, so that I can see what work I need to complete over the next few weeks.”
- 8. Useful Commands • grailscreate-app pomodoro • grails create-domain-class <domain> • grails generate-all <domain> • grails generate-controller <domain> and add ‘static scaffold = true’ to controller
- 9. Considerations • Associations • One-to-One •One-to-Many • Many-to-Many • Constraints &Validation • Time-Stamping? • Default values (and field values inViews?)
- 10. You did createsome tests first, right?
- 11. Implementation class Task { Inventoryinventory String description static belongsTo = [Inventory] static constraints = { description(nullable: false, blank: false) } } class Inventory { String name static hasMany = [tasks: Task] static constraints = { name(nullable: false, blank: false, unique: true) } }
- 12. Domain Tests class InventoryTestsextends GrailsUnitTestCase { void testConstraints() { def existingInventory = new Inventory(name: "Paul’s Inventory") mockForConstraintsTests(Inventory, [ existingInventory ]) ! ! // Validation should fail if both properties are null. ! ! def inventory = new Inventory() ! ! assertFalse inventory.validate() ! ! assertEquals "nullable", inventory.errors["description"] ! ! // So let's demonstrate the unique constraint. ! ! inventory = new Inventory(name: "Paul’s Inventory") ! ! assertFalse inventory.validate() ! ! assertEquals "unique", inventory.errors["name"] ! ! // Validation should pass! ! ! inventory = new Inventory(name: "John’s Inventory") ! ! assertTrue inventory.validate() ! } }
- 13. Gotcha! • Potential performanceissue with mapped collections: • Adding to the Set requires loading all instances from the database to ensure uniqueness • Likewise for mapped List • Works fine in development, but what if you have 1,000,000+ rows?
- 14. Implementation (2) class Task{ Inventory inventory String description static constraints = { description(nullable: false, blank: false) } } class Inventory { String name }
- 15. Side-effects? • Different syntaxfor adding Tasks • No cascading deletes • Custom finder required to find all Tasks in an Inventory • Scaffolding breaks!
- 16. User Story 2 “Asa pomodoro fan, I would like to be able move tasks onto a ‘To Do Today’ sheet, so that I can see work to be completed today and view my work history.”
- 17. Considerations • Does the‘Today’ list share any common attributes with the Inventory? • How about a more intuitive URL scheme?
- 18.
- 19. Level 1 -Views Controller Model PageViewPageViewPageView Model Model
- 20. Level 1 ‘Smells’ •Logic built into pages: • Overuse of Request Parameters • If-Then tags • Inline groovy using ${...} • Poor use of layouts • Little use of tags • Domain classes as simple ‘active records’ • Page-based information architecture
- 21.
- 22. Level 1-2 Refactoring •Move logic out of pages into controllers • Reduce pages into fragments • Use layouts to construct device or stakeholder- centric views from pages and fragments • Use available tag libraries • Create your own tag libraries! • Stylesheets rule - minimise markup
- 23. User Story 3 “Asa pomodoro fan, I would like to have an optimised workflow for US2, so that I can save time and reduce input mistakes.”
- 24. Considerations • Web Flowplugin? • Command Objects? • What changes need to be made to domain classes?
- 25. Web Flow class InventoryController{ … def inventoryFlow = { showInventory { on("done").to "saveInventory" on("continue").to "addTask" } … addTask { redirect(controller:"task", action:"create") } saveInventory() } } <g:form action="inventory"> <g:submitButton name="continue" value="Add Another"></g:submitButton> <g:submitButton name="done" value="I’m Done"></g:submitButton> </g:form>
- 26. User Story 4 “Asa pomodoro fan, I would like to be able update the number of iterations I’ve completed on each task in my ‘To Do Today’ list, so that I can keep track of my progress and improve my future estimates.”
- 27. Considerations • Can wedo this without page refreshes? • How can we test this? • Domain changes?
- 28. Level 2 -Controllers Controller Domain Controller Controller Domain Domain Domain Layout Fragments Fragments Layout Fragments Fragments Layout Fragments Fragments
- 29. Level 2 ‘Smells’ •Large, complex Controllers • Different scenarios driven by ‘If/Then’ logic • Content negotiation increases complexity further • Many similar controller methods (not DRY!) • Poorly handled Transactions
- 30. ? Level 3 -Services ? Services Controllers Views
- 31. Level 2-3 Refactoring •Move domain transaction logic out of controllers into services • Controllers should be ‘glue’ that binds business services to UI • Service methods should reflect business scenarios • Make use of transactional capability of services
- 32. User Story 5 “Asa pomodoro partner, I would like a simple REST API over your daily task view, so I can integrate your data into my application.”
- 33. Considerations • Don’t clutteryour Controllers! • REST-ful URLs • Content negotiation? • Custom XML/JSON formats?
- 34. RESTful URL Mappings staticmappings = { "/task/$id?"(resource:"task") } static mappings = { "/task/$id"(controller:"task") { action = [GET:"show", PUT:"update", DELETE:"delete", POST:"save"] } } static mappings = { "/task/$id"(controller:"task", parseRequest:true) { action = [GET:"show", PUT:"update", DELETE:"delete", POST:"save"] } }
- 35. Content Negotiation class InventoryController{ def inventory def list = { this.inventory = Inventory.list() withFormat { html inventoryList:inventory json { render inventory as JSON } xml { render inventory as XML } } } }
- 36. Custom Formats? def listAsXML= { def inventory = Inventory.get(params.id) def tasks = inventory.tasks render(contentType:"text/xml") { inventory(name:inventory.name) { tasks { for(t in tasks) { task(title:t.title) ! } }! } } }
- 37. User Story 6 “Asa pomodoro fan, I’d like to be able to add unplanned and urgent tasks to the bottom of my daily list, so that I can track and manage interruptions.”
- 38. Level 3 -Services Controller Domain Controller Controller Domain Domain Domain Services Layout Fragments Fragments Layout Fragments Fragments Layout Fragments Fragments
- 39. Level 3 ‘Smells’ •Large, complex Services • Services acting as proxies for domain behaviour • ‘Cut-and-paste’ methods
- 40. ? Level 4 -Libraries Libraries Services Controllers Views
- 41. Level 3-4 Refactoring •Move common code out of services into POGO’s (or POJO’s) • Enrich our domain model to simplify services: • Named Queries • Derived Properties • Criteria: Conjunctions, Disjunctions, Projections, Restrictions
- 42. User Story 7 “Asa pomodoro fan, I would like to be able to search for tasks on my inventory through a simple interface, so I can find and modify them easily.”
- 43. Level 4 -Libraries Controller Domain Controller Controller Domain Domain Domain Services Libraries Libraries Layout Fragments Fragments Layout Fragments Fragments Layout Fragments Fragments
- 44. Level 4 ‘Smells’ •Large, monolithic application • Increased cognitive overhead • New starters struggle • Components ‘cut and pasted’ into similar projects
- 45. Plugins Level 5 -Plugins Libraries Services Controllers Views
- 46. Level 4-5 Refactoring •Componentise the application into plugins • Construct applications by combining plugins • Could your application itself be constructed as a plugin for an organisation’s product suite? • Writing plugins that modify the Grails/Spring context is beyond the scope of this workshop!
- 47. User Story 8 “Asa pomodoro fan, I would like a simplified version of my Inventory, so I can view it on my iPhone.”
- 48. Useful Commands • grailscreate-plugin <plugin> • grails package-plugin • grails install-plugin /path/to/plugin/grails- example-0.1.zip
- 49. Layouts and Fragments <g:includeaction="show" id="1" /> <g:include action="show" id="${currentTask.id}" /> <g:include controller="task" /> <g:include controller="task" action="list" /> <g:include action="list" params="[sort:'title', order:'asc'] /> <html> <head> <title><g:layoutTitle default="An example decorator" /></title> <g:layoutHead /> </head> <body> <div class="menu"><!--my common menu goes here--></menu> <div class="body"> <g:layoutBody /> </div> </div> </body> </html>
- 50. Layout Options • Inyour views: <meta name="layout" content="main"></meta> • In your controller: static layout = 'task' static layout = 'custom/task' • By Convention: grails-app/views/layouts/task.gsp grails-app/views/layouts/task/list.gsp • Inline: <g:applyLayout name="myLayout" template="taskTemplate" collection="${tasks}" /> <g:applyLayout name="myLayout" url="http://www.google.com" /> <g:applyLayout name="myLayout">The content to apply a layout to</g:applyLayout>
- 51. Level 5 -Plugins Controller Domain Controller Domain Domain Plugins Page View Page View Controller Services Libraries / Plugins Domain Domain Layout Fragments Fragments Layout Fragments Fragments Services Libraries Libraries
- 52.
- 53.