Combined attribute test on childnode for xpath query

[Christoph Kiehl <ch...@sulu3000.de>]

Hi all,

I'm not a master of XPath at all, so may someone can tell me if the following is 
possible with Jackrabbit, and if yes, how.

I need to execute a query like this:

//element(*, nt:foo)[test/*[@foo='a' and @bar='b']]

This means I need all nodes of type "nt:foo" which have "foo=a" and "bar=b" on 
_one_ specific childnode. If I write it like that

//element(*, nt:foo)[test/@foo='a' and test/@bar='b']

it seems like the condition is matched if for example "test[1]/@foo='a' and 
test[2]/@bar='b'" is true.

Thanks,
Christoph

Re: Combined attribute test on childnode for xpath query

[Marcel Reutegger <ma...@gmx.net>]

Christoph Kiehl wrote:
> Could you give me a pointer what has to be done to support this? Is it a 
> desirable feature at all?

It certainly is a desirable feature, but I wouldn't invest too much time at this 
point because we will soon start with changes / enhancements for JCR 2.0.

> Or is it maybe easier to implement support for the ancestor axis? The 
> query could be rewritten like this:
> 
> //element(*, nt:foo)/test[@foo='a' and @bar='b']/..

yes, that's probably easier. because the query tree structure is quite limited 
when it comes to predicates.

regards
  marcel

Re: Combined attribute test on childnode for xpath query

[Christoph Kiehl <ch...@sulu3000.de>]

Marcel Reutegger wrote:

>> I need to execute a query like this:
>>
>> //element(*, nt:foo)[test/*[@foo='a' and @bar='b']]
> 
> I guess you rather mean:
> 
> //element(*, nt:foo)[test[@foo='a' and @bar='b']]

Yes ;)

> but in any case, this is currently not possible in jackrabbit.

Could you give me a pointer what has to be done to support this? Is it a 
desirable feature at all?

Or is it maybe easier to implement support for the ancestor axis? The query 
could be rewritten like this:

//element(*, nt:foo)/test[@foo='a' and @bar='b']/..

>> This means I need all nodes of type "nt:foo" which have "foo=a" and 
>> "bar=b" on _one_ specific childnode. If I write it like that
>>
>> //element(*, nt:foo)[test/@foo='a' and test/@bar='b']
> 
> that's kind of the workaround for the above mentioned limitation.
> 
>> it seems like the condition is matched if for example 
>> "test[1]/@foo='a' and test[2]/@bar='b'" is true.
> 
> correct.
> 
> looks like another argument for Davids DM Rule #4.

Well ... I think it's kind of a weak argument ;) I would better like to add the 
missing feature to Jackrabbit.

Cheers,
Christoph

Re: Combined attribute test on childnode for xpath query

[Marcel Reutegger <ma...@gmx.net>]

Christoph Kiehl wrote:
> I'm not a master of XPath at all, so may someone can tell me if the 
> following is possible with Jackrabbit, and if yes, how.
> 
> I need to execute a query like this:
> 
> //element(*, nt:foo)[test/*[@foo='a' and @bar='b']]

I guess you rather mean:

//element(*, nt:foo)[test[@foo='a' and @bar='b']]

but in any case, this is currently not possible in jackrabbit.

> This means I need all nodes of type "nt:foo" which have "foo=a" and 
> "bar=b" on _one_ specific childnode. If I write it like that
> 
> //element(*, nt:foo)[test/@foo='a' and test/@bar='b']

that's kind of the workaround for the above mentioned limitation.

> it seems like the condition is matched if for example "test[1]/@foo='a' 
> and test[2]/@bar='b'" is true.

correct.

looks like another argument for Davids DM Rule #4.

regards
  marcel