Re: [xsl] One nodeset, multiple branches

[Wendell Piez <wapiez at mulberrytech dot com>]

Eric,

You have the problem half solved. It's not really an XPath thing, exactly; 
it's in  having to establish a relation between each <group> that contains 
<right> descendants, with the users assigned to that group.

As you have seen,

user[@username='evitiello]/rights/right

(or, more comprehensively but less efficiently, 
user[@username='evitiello]//right)

will get the user's own 'proper' rights (when the user is you :-).

To get the rights associated with groups assigned to the user, is of course 
a bit trickier. First:

<xsl:variable name="usergroups" 
select="user[@username='evitiello']//group/@name"/>

Gets the @name attributes on the groups belonging to your user (you) into a 
variable.

Then, get rights associated with these groups:

//group[@name=$usergroups]//right

(Again, this is comprehensive but not maximally efficient for your case.)

This relies on the fact that a node-set (here, a group/@name) is equal to 
another node-set (here, your variable, a collection of names) if any node 
in one node-set has a string value equal to any node in the other.

Combining these two XPaths does everything you need except de-duplicating 
the list. To do that, I'm afraid you'll have to iterate over the node-sets 
and check each node's preceding:: or following:: axis. This will get 
expensive if your data set is large.

Another approach, potentially much more efficient, is to use keys ... and 
that will let you de-duplicate as well (maybe I'll tackle that later if 
Jeni doesn't first ;-).

I don't think this XPath is over your head; it's just a bit hard to see 
around corners until you learn to use other features of the language 
(node-sets bound to variables; keys) as mirrors.

Cheers,
Wendell

At 09:22 AM 12/19/01, you wrote:
>Hi.
>
>I have the following XML:
>
><?xml version="1.0"?>
><access>
>         <users>
>                 <user username="evitiello">
>                         <realName>Eric Vitiello</realName>
>                         <rights>
>                                 <right module="news" access="add"/>
>                                 <right module="page" access="edit"/>
>                         </rights>
>                         <userGroups>
>                                 <group name="administrators"/>
>                         </userGroups>
>                 </user>
>         </users>
>         <groups>
>                 <group name="marketing">
>                         <rights>
>                                 <right module="news" access="add"/>
>                         </rights>
>                 </group>
>                 <group name="administrators">
>                         <rights>
>                                 <right module="news" access="add"/>
>                                 <right module="news" access="edit"/>
>                                 <right module="news" access="delete"/>
>                                 <right module="page" access="add"/>
>                         </rights>
>                 </group>
>         </groups>
></access>
>
>I would like to be able to return a nodeset that contains all of the 
>"rights" that a given user has.


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Wendell Piez                            mailto:wapiez@mulberrytech.com
Mulberry Technologies, Inc.                http://www.mulberrytech.com
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