using XPath with DOM

[Swapna Gupta <SG...@cs.ua.edu>]

Hello,

Please help me solve my problem, which is thus:

I am constructing an XML DOM tree and saving it in Xindice as DOM tree,
following is the code snippet for it:

 

DOMImplementation domImpl = new DOMImplementationImpl();

 Document doc = domImpl.createDocument(null, "lesson", null);

 Element root = doc.getDocumentElement();

 root.setAttribute("xmlns",
"http://swel.cs.ua.edu:8080/swapna/lessons");

 root.setAttribute("xmlns:xsi",
"http://www.w3.org/2001/XMLSchema-instance");

root.setAttribute("xsi:schemaLocation","
http://swel.cs.ua.edu:8080/swapna/lessons E:/SWEL-Shared/tomcat 

server/webapps/useraccounts/swapna/lessons_learned_system/lessons_new.xs
d" ); 

 Element titleElement = doc.createElement("title");

 Text titleText = doc.createTextNode(topic); /*topic contains a string*/

 titleElement.appendChild(titleText);

 root.appendChild(titleElement);

.....

.....

...

 

In the end, after constructing the complete DOM tree, I store it in
Xindice as:

DatabaseManager.getCollection("xmldb:xindice://swel.cs.ua.edu:4080/db/"
+ colName); /*colName contains a String*/

       XMLResource document = (XMLResource) col.createResource(null,

        "XMLResource");

       document.setContentAsDOM((Node)doc);

       col.storeResource(document);

......

 

Now, I am trying to use XPath to make queries into these documents
stored in Xindice. If I use a query like "/descendant::*", and output
their result using getContent(), I can see all my documents. But, if I
do a query like "/descendant::lesson" (lesson is the root element), the
query finds no matches. On the other hand, if I store my documents by
reading their contents as String from an XML file, I can query them
using XPath correctly.

 

Are there any issues associated with using XPath for querying documents
saved as DOM trees using setContentAsDOM() in Xindice?

 

Please help.

 

Thanks,

Swapna

 

 

Re: using XPath with DOM

[Vadim Gritsenko <va...@verizon.net>]

Swapna Gupta wrote:

> Hello,
>
> Please help me solve my problem, which is thus:
>
> I am constructing an XML DOM tree and saving it in Xindice as DOM 
> tree, following is the code snippet for it:
>
> DOMImplementation domImpl = new DOMImplementationImpl();
>
> Document doc = domImpl.createDocument(null, "lesson", null);
>
> Element root = doc.getDocumentElement();
>
> root.setAttribute("xmlns", "http://swel.cs.ua.edu:8080/swapna/lessons");
>
> root.setAttribute("xmlns:xsi", 
> "http://www.w3.org/2001/XMLSchema-instance");
>
> root.setAttribute("xsi:schemaLocation"," 
> http://swel.cs.ua.edu:8080/swapna/lessons E:/SWEL-Shared/tomcat
>
> server/webapps/useraccounts/swapna/lessons_learned_system/lessons_new.xsd" 
> );
>
> Element titleElement = doc.createElement("title");
>
> Text titleText = doc.createTextNode(topic); /*topic contains a string*/
>
> titleElement.appendChild(titleText);
>
> root.appendChild(titleElement);
>
> …..
>
> …..
>
> …
>
> In the end, after constructing the complete DOM tree, I store it in 
> Xindice as:
>
> DatabaseManager.getCollection("xmldb:xindice://swel.cs.ua.edu:4080/db/" 
> + colName); /*colName contains a String*/
>
> XMLResource document = (XMLResource) col.createResource(null,
>
> "XMLResource");
>
> document.setContentAsDOM((Node)doc);
>
> col.storeResource(document);
>
> ……
>
> Now, I am trying to use XPath to make queries into these documents 
> stored in Xindice. If I use a query like "/descendant::*", and output 
> their result using getContent(), I can see all my documents. But, if I 
> do a query like "/descendant::lesson" (lesson is the root element), 
> the query finds no matches. On the other hand, if I store my documents 
> by reading their contents as String from an XML file, I can query them 
> using XPath correctly.
>
> Are there any issues associated with using XPath for querying 
> documents saved as DOM trees using setContentAsDOM() in Xindice?
>

I think the problem is that your xpath uses default namespace, while in 
the document you try to use "http://swel.cs.ua.edu:8080/swapna/lessons" 
namespace. At least that's how I interpreted your line:
root.setAttribute("xmlns", "http://swel.cs.ua.edu:8080/swapna/lessons");
but I think correct way to do it would be to pass it to createDocument:

Document doc = 
domImpl.createDocument("http://swel.cs.ua.edu:8080/swapna/lessons", 
"lesson", null);



Try this xpath: "/descendant::*:lesson", it should match any namespace.

Vadim