RE: sub-tree filtering proposals

["Michael Walton" <Michael.Walton@za.flextronics.com>]

Hi

I've been following netconf for a couple of weeks now. Hopefully I can
add a bit of noise to a quiet list. 

For now - I experimented a little with XPath expressions in PyXML and
found one possible answer to Juergen's question:


>> C.6) Specific elements from a specific <user> entry
>> 
>> Request:
>> 
>>   <rpc message-id="101" xmlns="netconf-uri">
>>     <get>
>>       <data>
>>         <filter filter-type="subtree">
>>           <users xmlns="http://example.com/schema-1";>
>>             <user>
>>               <name>fred</name>
>>               <type/>
>>               <full-name/>
>>             </user>
>>           </users>
>>         </filter>
>>       </data>
>>     </get>
>>   </rpc>
>> 
>> Reply:
>> 
>>   <rpc-reply message-id="101" xmlns="netconf-uri">
>>     <data>
>>       <users xmlns="http://example.com/schema-1";>
>>         <user>
>>           <name>fred</name>
>>           <type>admin</type>
>>           <full-name>Fred Flintstone</full-name>
>>         </user>
>>       </users>
>>     </data>
>>   </rpc-reply>
>>       
>> Notes:
>> 
>>  - This filter contains two containment nodes (users, user),
>>    one content match node (name), and two selector nodes
>>    (type, full-name).
>>  - All instances of the 'type' and 'full-name' elements in
>>    the same siibling set containing 'name', for which the value 
>>    of 'name' equals "fred", are selected in the filter output.
>>    The 'company-info' element is not included because the
>>    sibling set contains selection nodes.
>
>The XPATH expression "//users/user[name="fred"]/name" will just return
>the name element - not sure how one can select multiple elements with
>XPATH in this case (but I am an XPATH beginner - perhaps someone out
>there knows the answer).
>

An expression that returns name, type and full-name looks like this:

//users/user[name="fred"]/*[name()="name" or name()="type" or
name()="full-name]

... which is somewhat ugly, or you could use the "pipeline" operator as
suggested by Juergen:

//users/user[name="fred"]/name | //users/user[name="fred"]/type |
//users/user[name="fred"]/full-name

... but that seems inefficient.

Michael Walton
Flextronics South Africa

C301 Warehouse Building
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Observatory, 7925, South Africa
+27 21 442 1240      Main
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mailto:michael.walton@za.flextronics.com


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