On Thu, Jan 28, 2010 at 5:23 PM, Naftoli Gugenheim <[email protected]>wrote:
> Neat. So it's a flatMap?
>
No, it's not flatMap. It has some of the characteristics of flatMap, but
the function returns a Box[T], not an Iterable[T]
> Should we replace the pattern used often in binding lists
> Author.findAll.flatMap { a => bind ... }
> with
> Author.findMap() { a => bind ... }
> when the list is large or its elements are big?
>
I don't think so.
>
>
> -------------------------------------
> David Pollak<[email protected]> wrote:
>
> def findMap[T](by: QueryParam[A]*)(f: A => Box[T])
>
> Your function, f, will be called as each row is pulled back from the
> database. If your function returns Empty, the row will not be included in
> the final result. You can also do fun stuff like:
>
> MyModel.findMap(){
> row -> row.name.is match {
> case x if x.length < 4 => Full(x)
> case _ => Empty
> }}
>
> This will return a List[String] for all the people with short names. Your
> function is called as each row is processed, so the whole list is not
> loaded
> into memory.
>
> If you wanted to simulate a foreach here, you'd just return Empty from the
> function every time.
>
>
> On Wed, Jan 27, 2010 at 9:58 PM, Naftoli Gugenheim <[email protected]
> >wrote:
>
> > MetaMapper has a findAll method, which creates a statement based on its
> > parameters, and then iterates over the ResultSet creating Mappers and
> > putting them into a List.
> > It would be neat if it was possible to process the generated Mappers one
> by
> > one instead of loading them into a list. This way large ResultSets don't
> > need to result in a big List in memory.
> > Is such a thing possible today? If not, what would it take to implement?
> > One approach would be foreach/map/flatMap methods. Another would be a
> find
> > method that returns a lazy list or an Iterator.
> > Thanks.
> >
> >
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>
>
>
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