This presentation is giving a short overview of forms, site map and mappers in the lift framework.

1. The Lift framework
at least some parts of

2. agenda - How we divide

3. forms in lift

4. some facts
 Standard GET/POST support
 AJAX and JSON forms support
 No HTML form tags needed
 Implement as snippet in Scala
 Form generated by net.liftweb.http.SHtml
 Stateless by default
 Extend StatefulSnippet
 Use RequestVars for statefull purpose

5. some short dive 1 / 2

6. some short dive 2 / 2

7. checkbox - text area - password inputs

8. text area - password inputs
 Mostly like standard HTML input elements
 Generated by Shtml
 Overload XML with Pair(String, String)
 “attribute” → ”value”

9. checkbox
 Not submitted if unchecked

10. hidden element
 Not a plain value like in HTML
 Defined function is called on submit
 For logging, debugging or other
calculations

11. Link - radio - (multi) selection

12. Link
 Like an HTML anchor
 Defined function is invoked on click
 Passing objects to linked page

13. radio button
 Set of radio buttons with String labels

14. (multi) selection
 selection
 List of options as Pair(value, display)
 Only one item may be selected
 multiselection
 Multiple select or pre-select
 Callback function proceeds for every returned value
 selectObj
 Handles passed objects as Pair(object, display)

15. file upload 1/2
 Special case of form submission
 SHtml generates file upload
element with callback
 File is typed as FileParamHolder
refenced by SHtml
 Whole file is loaded into
memory on complete

16. file upload 2/2

17. site map

18. site map - facts
 Provides a map for your site
 Not only links and basic menu functionality
 Nested menus with hierarchies
 Grouping menus
 Access control mechanism
 Request URL rewriting
 State-dependent computations for page titles,
page-specific snippets, etc.

19. Basic siteMap 1/2

20. Basic sitemap 2/2
 Creating menu entries with unique Loc
reference
 Allow access to any pages with help of
match
 Nested menu holds one or more child
menus

21. customize display of menu
 Hide menu entries to restrict access
 Control menu item text
 Render menu title
 Customize menu with help of CSS
 Add JavaScript functionality
 Build menu groups

22. access control
 Extending binary control of given request
 "matches→display" otherwise don't display
 If LocParam
 Test Function evaluates given path
 Message Function returns failure response
string
 User redirected to page with display for error
state
 Unless LocParam
 Mirrors Test Function of If LocParam

23. Page-specific Rendering

24. The mapper and record
frameworks
- Making things persistent -

25. What is persistence?
“Persistence in computer science refers to the
characteristic of data that outlives the execution
of the program that created it. Without this
capability, data would only exist in RAM, and
would be lost when this RAM loses power, such as
on computer shutdown. This is achieved in
practice by storing the data in non-volatile
storage such as a hard drive or flash memory.
”
Wikipedia

26. and mapping?
User
passwort:String
name:String
street:String
postnr:Longint

27. record vs. mapper
 Mapper is original Lift persistence
framework
 Closely tied to JDBC
 Record is new refactorization of Mapper
 Define own Mapping Strategies (XML, JDBC,
JPA)
 Mapper will be deprecated as soon as
Records is stable
 Mapper will be used in this presentation

28. Get connected
 Extend
net.liftweb.mapper.ConnectionManager
trait
 Implement methods: newConnection and
releaseConnection

29. Dbvendor extends connectionManager
 name parameter
used to have
multiple databases
 newConnection
needs to return a
Box[java.sql.Connecti
on]
 releaseConnection
used to have
complete control of
the connection
lifecycle
 Declare object in
Boot.scala
 Call the
DB.defineConnection
Manager to bind
Manager into the
Mapper

30. make my class persistent
 Class Transaction from the PocketChange application
 We want to store:
 Date
 Description with a max length of 100 chars
 Amount of money used in a transaction
 And a account we want to reference to (described in detail
later)

31. What have I typed here?
 Use LongKeyedMapper trait:
 Provide primary key for our entity
 Key should be long
 IdPK trait implements getPrimaryKeyField-method
 Defined as object due to MetaMapper, who needs access for
validation
 getSingleton defines the MetaObject

32. how to set fields?
 Fields are no instance members:
 Use apply method to set:
 Use is to get:

33. Object relationship - one to many

34. Object relationship - many to many

35. Indexing
 More complex indexing via usage of the
Index, IndexField and BoundedIndexField
case classes

36. schema mapping
 Create database schema according to
your objects
 Declared in Boot.scala

37. Working with entities
 MetaMapper is providing a lot of
operations for an entity:

38. how to query data
 findAll returns all instances
 Use flag to define criterias to limit search
result (trait QueryParam)
 By is used for direct value comparison
 BySQL let us use plain SQL as where clause

39. Other Queryparams to search for data

40. Getting things ordered

41. from mapping to html
 asHTML is rendering the mapper instance
„as HTML“.
 Overriding for own behaviour
 eg own date format

42. from mapping to a form
 toForm is making it easy to create a form
appropriate to an instance
 Third method has a „redo“ snippet parameter
to save status
 User do not have to re-enter everything

43. from form to validation
 Validate submitted data
 User is not allowed to enter dates in the future
 Link function to validation

44. crud support
 Create, read, update, delete:
 Use CRUDify trait

45. Doing it oldschool - sql 1/2
 findAllByPreparedStatement
 findAllByInsecureSql
 Executes the String you submit directly without
any checks

46. Doing it oldschool - sql 2/2
 DB.runQuery provides support for non-
entity SQL queries

47. Protouser
 ProtoUser trait defines some basic fields for
a user (email, firstName, lastName,
password and superUser)
 Already some defs used to format the
fields for display or to provide form labels

48. megaprotouser
 Extends the ProtoUser trait
 Automatically handle all of the scaffolding
for a complete user management system
 User registration page
 Login page
 Lost password page
 Change password page
 User edit page
 Simple method to generate SiteMap

49. [- Showing some code in eclipse -]

50. conclusion
 Concepts are pretty nice
 Getting things done very quick out of box
 Scala as scripting language makes it mighty
 Would have been better to do presentations
AFTER project
 Pretty hard to „give control“ to the framework
(„What is happening in the background?“)
 Lift book is bad.
 We would still prefer (G)Rails due to better
tooling and experience

51. Disclaimer
 All images in this presentation are downloaded from flickr.com and marked with the creativecommons licence for
commercial use.
 This presentation is restricted with the creativecommons licence (http://creativecommons.org/licenses/by-
nd/3.0/de/deed.en):