How to access XML elements one at a time using xslt?

Techcarol · January 10th, 2011, 03:40 PM

Hello,

Code:

This is my XML document.
<?xml version="1.0"?>
<company>
    <employee>
        <firstname>Tom</firstname>
        <middlename>WWW</middlename>
        <lastname>Cruise</lastname>
    </employee>
    <employee>
        <firstname>Paul</firstname>
        <lastname>Enderson</lastname>
    </employee>
</company>

Below is my XSLT which I have created.

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    exclude-result-prefixes="xs"
    version="2.0">
    <xsl:template match="/">
           <xsl:call-template name="subtree">
            <xsl:with-param name="parents" select="/"/>
           </xsl:call-template>
        <xsl:copy-of select="."/>
       
    </xsl:template>      
    <xsl:template name="subtree">
        <xsl:param name="parents"/>
        <xsl:for-each select="$parents/*">
            <xsl:variable name="current-group" select="$parents/*[name() = name(current())]"/>
            <xsl:if test="count($current-group[1]|.) = 1">
                <xsl:call-template name="subtree">
                        <xsl:with-param name="parents" select="$current-group"/>
                    </xsl:call-template>   
            </xsl:if>
        </xsl:for-each>
   </xsl:template>   
</xsl:stylesheet>

OUTPUT
<?xml version="1.0" encoding="UTF-8"?><company>
    <employee>
        <firstname>Tom</firstname>
        <middlename>WWW</middlename>
        <lastname>Cruise</lastname>
    </employee>
    <employee>
        <firstname>Paul</firstname>
        <lastname>Enderson</lastname>
    </employee>
</company>

My requirement is to design a stylesheet which when applied to any XML document should access each XML element at a time so that I can use it further for creating another XML document as per my requirement. Could you please let me know how to do this? Once I am able to access particular element, is it possible to know who all are its child elements?

Thanks in advance,
Komal

samjudson · January 10th, 2011, 04:12 PM

You just described XSLT - that is what it does.

The only line in your XSLT above that does anything is <xsl:copy-of select="."/> - the rest is just junk.

Perhaps if you could give us an example of what you WANT the output too look like then we might be able to help you.

Techcarol · January 10th, 2011, 05:04 PM

Quote:

Originally Posted by samjudson

You just described XSLT - that is what it does.

The only line in your XSLT above that does anything is <xsl:copy-of select="."/> - the rest is just junk.

Perhaps if you could give us an example of what you WANT the output too look like then we might be able to help you.

Hello,

My requirement is to design a stylesheet which will work with any XML document. Something similar to generalized stylesheet.
For eg.
If the above XML document is used as input for XSLT for the first time, it should produce the same XML document again. But second time, if I use another XML document with different structure as input, the same stylesheet should get applied and produce XML document. In order to this,I was trying to access one XML element at a time rather than the entire XML structure. How is this possible?

I hope this clarifies my requirement.

Thanks,
Komal

samjudson · January 11th, 2011, 05:16 AM

I'm sorry, you still aren't making your requirements clear.

If all the stylesheet does is output whatever is input then I see the point. If this is not what you mean then you need to provide a concrete example of where the output differs from the input.

Perhaps look up the "identity xslt template" will give you some clues, I don't know.

Techcarol · January 11th, 2011, 08:29 PM

Quote:

Originally Posted by samjudson

I'm sorry, you still aren't making your requirements clear.

If all the stylesheet does is output whatever is input then I see the point. If this is not what you mean then you need to provide a concrete example of where the output differs from the input.

Perhaps look up the "identity xslt template" will give you some clues, I don't know.

Hi Sam,

Thanks for your reply. Please see below my actual requirement.

To write a stylesheet which, when you apply it to an XML document, produces Java code as output: this Java code, when you run it, should (using the DOM libraries) output an XML document which will be the same as the XML document you started with.1. You should have one stylesheet which will function in the way described on any input XML
document.

Could you provide the stylesheet which can be applied to any XML document?

I am getting confused with accessing the elements since I have not worked much on XSLT.

Thanks in advance,
TechCarol

samjudson · January 12th, 2011, 06:07 AM

As I keep saying, could you give us an example input XML and what you want to be output.

We don't know how you want you java code to look, what libraries or jar files you might be using, where you want to store the output from the java, any number of other things.

I've already said to look up the identity template: http://www.dpawson.co.uk/xsl/sect2/identity.html

You are probably interested in looking up information on the node() and text() functions, and the @* and * xpath axis abbreviations.

Techcarol · January 12th, 2011, 09:20 AM

Quote:

Originally Posted by samjudson

As I keep saying, could you give us an example input XML and what you want to be output.

We don't know how you want you java code to look, what libraries or jar files you might be using, where you want to store the output from the java, any number of other things.

I've already said to look up the identity template: http://www.dpawson.co.uk/xsl/sect2/identity.html

You are probably interested in looking up information on the node() and text() functions, and the @* and * xpath axis abbreviations.

This is my input XML file and output should be also the same.
<?xml version="1.0"?>
<company>
<employee>
<firstname>Tom</firstname>
<middlename>WWW</middlename>
<lastname>Cruise</lastname>
</employee>
<employee>
<firstname>Paul</firstname>
<lastname>Enderson</lastname>
</employee>
</company>

The main requirement is designing of stylesheet in such a way that if my input XML file changes, the same stylesheet when applied to the new XML document, should produce java code which in turn will produce the same XML file as output.

Hope now the requirement is clear.

Let me know if you need any more information.

samjudson · January 12th, 2011, 10:04 AM

I think I am being generous here, but I will ask for the third time.

Show us exactly what you want your output to look like for a given input. DO NOT just describe it again, actually show us the java code you want to see!

Techcarol · January 12th, 2011, 11:22 AM

Quote:

Originally Posted by samjudson

I think I am being generous here, but I will ask for the third time.

Show us exactly what you want your output to look like for a given input. DO NOT just describe it again, actually show us the java code you want to see!

Hello,

Please see below java code which needs to be generated when XSLT is transformed.

[CODE]
import java.io.*;
import javax.xml.parsers.*;
import javax.xml.transform.*;
import javax.xml.transform.dom.*;
import javax.xml.transform.stream.*;
import org.w3c.dom.*;
public class TestElements
{
public static void main(String[] argv) throws Exception
{

DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
Document doc = docBuilder.newDocument();
Element rootElement = doc.createElement("company");
doc.appendChild(rootElement);
Element childElement=doc.createElement("employee");
company.appendChild(childElement);
}
}

mhkay · January 12th, 2011, 11:52 AM

>To write a stylesheet which, when you apply it to an XML document, produces Java code as output: this Java code, when you run it, should (using the DOM libraries) output an XML document which will be the same as the XML document you started with.

OK, I've finally understood what you are trying to do. But I don't understand why! The simplest Java code to generate is surely code that takes the XML document as a character string and calls the DOM's parse() method.

To what extent is it actually necessary to do this by generating calls on DOM methods such as createElement() and appendChild()? For example, would it be equally acceptable to generate methods representing SAX events such as startElement() and endElement(), so that the Java program builds the DOM using a SAX-to-DOM builder?

If you want to do it the way you have suggested, it's certainly possible. The Java program might get quite large, and if the XML is more than 10Kb or so, I wouldn't be surprised if the generated Java breaks compiler limits. It doesn't need many template rules either - one per node kind should be fine. Something like this (using generate-id() to produce variable names that refer to the nodes):

Code:

<xsl:template match="*">
  Element <xsl:value-of select="generate-id()"/> = doc.createElement("<xsl:value-of select="name()"/>");
  <xsl:value-of select="generate-id(..).appendChild(<xsl:value-of select="generate-id()"/>);
  <xsl:apply-templates select="@*/>
  <xsl:apply-templates/>
</xsl:template>

and then similar templates to match attribute nodes, text nodes, and so on.