I can answer b) -- S.param("image").flatMap(asLong)
asLong comes from BasicTypesHelpers.
-Ross
On Jan 4, 2010, at 4:42 PM, Jim Wise wrote:
>
> So, in my endless retweaking of this code, getting better (and
> learning
> more lift) on each pass, I've got a rewrite rule like this
>
> case RewriteRequest(ParsePath("image" :: image :: Nil, _, _,
> _), _, _) =>
> RewriteResponse("viewImage" :: Nil, Map("image" -> image))
>
> which is (eventually) handled by a snippet like this:
>
> def doShowOne(in: NodeSeq): NodeSeq =
> S.param("image").map(_.toLong) match {
> case Full(selected) =>
> ImageInfo.findByKey(selected) match {
> case Full(i) =>
> bind(...)
> case _ =>
> S.error("No such image!")
> }
> case _ =>
> S.redirectTo("/images")
> }
>
> Which works well if the referenced path component is the id of an
> existing image, or of a nonexistent image -- and throws an exception
> if
> the last path component can't be parsed as a long.
>
> I can catch the exception, of course, but I kinda feel there must be a
> cleaner way to do this -- either by not matching in the rewriting PF
> if
> the positional paramter "image" is not parseable as a long, or by
> making
> this another layer of casing in the snippet.
>
> So, two questions:
>
> a.) is there an idiom for this?
>
> b.) is there a good way to test if a String (or better, a Box
> [String])
> is convertable toLong without a try/catch?
>
> Thanks again,
> --
> Jim Wise
> jw...@draga.com
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