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From Jason E Bailey <...@apache.org>
Subject Re: [DISCUSSION][API][PROPOSAL] Adding Stream<Resource> generator to Sling API
Date Mon, 04 Jun 2018 18:02:05 GMT
You got it. Thats's what I was attempting to describe and that's the type of filtering we do
a lot of.

- Jason

On Mon, Jun 4, 2018, at 1:58 PM, Daniel Klco wrote:
> It seems redundant, but I think they're somewhat different concepts. The
> Predicate passed into the stream method is for evaluating the Resources
> relevant for traversal, whereas (at least I'm assuming) that any subsequent
> filters would filter the subsequent stream of resources. Having that sort
> of redundancy would allow you to traverse a structure like the following:
> 
> - myasset.jpg (dam:Asset)
>   - renditions (nt:folder)
>     - original (nt:file)
>     - rendition1.jpg (nt:file)
> 
> so if you wanted to get just a stream of the nt:file resources you could do:
> 
> myassetResource.stream(maxDepth(2)).filter(isResourceType("nt:file")).forEach(e
> -> {DO_SOMETHING});
> 
> I like the idea of adding the predicates either in the API or as a separate
> dependency as there are likely a few common patterns that would be used
> quite a bit.
> 
> -Dan
> 
> On Mon, Jun 4, 2018 at 1:31 PM, Jason E Bailey <jeb@apache.org> wrote:
> 
> >
> >
> > - Jason
> >
> > On Mon, Jun 4, 2018, at 12:35 PM, Daniel Klco wrote:
> >
> > >
> > > Rather than having another parameter, what about providing a
> > > ResourceChildrenPredicate? Based on the current API it looks like you'd
> > > have to provide the current resource to make this work, but it seems like
> > > it would be very useful to have a predicate which would only allow for
> > both
> > > direct children or children up to a particular depth. I'd see it useful
> > to
> > > provide 2-3 different default predicates to help with common activities:
> > >
> > > ResourceChildrenPredicate - filter the stream of resources based on their
> > > child status
> > > ResourceTypePredicate - filter the stream of resource based on their
> > > resource type
> > > ValuePredicate - filter the stream of resources based on a value in the
> > > resource's ValueMap
> > >
> > >
> >
> > Funny you should mention this. The original ResourceStream object came
> > from the whiteboard streams project. Which has a whole package  dedicated
> > to defining static predicates. There's even an expression languages in
> > their as well. However, for filtering, there's already a filter method that
> > a Stream provides. It's redundant to have a pre-filtered stream.
> >
> > However, as a limitation on the stream, you can do the same thing. It
> > would something like
> >
> > - resource.stream(CHILD_RESOURCES);
> >
> > or
> >
> > - resource.stream(maxDepth(1));
> >
> > maxDepth being a static method that you've imported from the appropriate
> > library that provides a Predicate
> >

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