On Wed, Aug 19, 2009 at 11:34 PM, Grant Wood <[email protected]> wrote:
>
> David,
>
> This is an excellent example of something that I was extremely
> frustrated with the first week learning Scala and Lift. I suspect it
> would make a great edition to the wiki, FAQ, and book as well; and
> save us newbs some time and heartache. If I could make one additional
> suggestion, it would be to also give an example of using a foreign key
> in a Select input (fairly common case). Having this close by the
> foreign key example would be handy.
>
> Something like:
>
> def add(form: NodeSeq) = {
> val refersto : RefersTo = RefersTo.create
>
> val allTargets = Target.allTargets.map(targ => (targ.id.toString,
> targ.name.toString))
>
> def doBind(form: NodeSeq) = {
> bind("refto", form,
> "name" -> refersto.name.toForm,
> "taget" -> select(allTargets, Full
> (refersto.target.toString), refersto.target.setFromAny),
> "submit" -> submit("Add Event", checkAndSave)
> )
> }
I think you just want to use the toForm method on the MappedForeignKey. You
have to implement the validSelectValues method:
def validSelectValues: Box[List[(KeyType, String)]] =
Full(TargetTable.findAll(OrderBy(TargetTable.id, Ascending)).map(t => (
t.id.is, t.name.toString)))
>
>
> def checkAndSave(): Unit = {
> event.validate match {
> case Nil => event.save ; S.notice("Added: " +
> event.name)
> case xs => S.error(xs) ; S.mapSnippet("Events.add",
> doBind)
> }
> }
>
> doBind(form);
> }
>
>
> Thanks for all your work on Lift. I look forward to being more able
> to contribute to Lift in the future. Great question Hannes.
>
> -Grant
>
> On Aug 19, 11:47 am, David Pollak <[email protected]>
> wrote:
> >
> > First, please take a look athttp://
> blog.lostlake.org/index.php?/archives/50-The-Scala-Option-clas...
> > It's a discussion about Option, which provides a subset of what Lift's
> Box
> > provides. It's also based on Scala 2.3 syntax... but you'll get the idea
> of
> > what Option/Box is all about.
> >
> > So, if you've got a LongKeyedMapper that is a target of a foreign key
> > reference from another Mapper class:
> >
> > class Taget extends LongKeyedMapper[Target] with IdPK {
> > ...
> >
> > object name extends MappedString(this, 64)
> >
> > }
> >
> > class RefersTo extends Mapper[RefersTo] {
> > object target extends MappedLongForeignKey(this, Target)
> >
> > }
> >
> > So, if I've got a RefersTo instance and I want to get the name from the
> > target foreign key reference:
> >
> > val rt: RefersTo = ...
> > val target: Box[Target] = rt.target.obj // load the FK reference, if you
> can
> > val nameBox: Box[String] = target.map(_.name.is) // you need the "is"
> part
> > so you get the String, not the MappedString
> > val name: String = nameBox openOr "N/A"
> >
> > But we can shorten the whole thing to:
> >
> > val name = rt.target.obj.map(_.name.is) openOr "N/A"
> >
> > In general, when you're starting out, write out the complex expressions
> as
> > separate lines with the types explicitly declared. Then refactor over
> and
> > over to make the code more concise. It might be worthwhile to leave the
> > original code in a comment so you can remind yourself the "exploded" view
> of
> > the expression.
> >
> >
> >
> > > thanks
>
> >
>
--
Lift, the simply functional web framework http://liftweb.net
Beginning Scala http://www.apress.com/book/view/1430219890
Follow me: http://twitter.com/dpp
Git some: http://github.com/dpp
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