XML Restructuring using XSLT

sillypepper · August 18th, 2009, 05:23 PM

Hi,

I need some help. I have an XML file and I need to change the structure of the information. I've included an example

Code:

<model>
	<concept name="example" uniqueID="10"/>
	<node>
		<name>StratA</name>
		<uniqueID>11</uniqueID>
		<class>static</class>
		<category>user</category>
		<parent>example</parent>
		<parentID>10</parentID>
		<functionality available="false"/>
	</node>	
	<node>
		<name>TempA</name>
		<uniqueID>14</uniqueID>
		<class>static</class>
		<category>user</category>
		<parent>example</parent>
		<parentID>10</parentID>
		<funtionality available="true"/>
	</node>
	<function nodename="TempA">
		<loop>
			<name>loop1</name>
		</loop>
		<fork>
			<kind>OR</kind>
		</fork>
		<sub>
			<type>dynamic</type>
		</sub>
	</function>
</model>

The above is what my XML looks like at the minute
and below is what I'd like it to look like.

Code:

<model>
	<concept name="example" uniqueID="10"/>
	<node>
		<name>StratA</name>
		<uniqueID>11</uniqueID>
		<class>static</class>
		<category>user</category>
		<parent>example</parent>
		<parentID>10</parentID>
		<functionality available="false"/>
	</node>	
	<node>
		<name>TempA</name>
		<uniqueID>14</uniqueID>
		<class>static</class>
		<category>user</category>
		<parent>example</parent>
		<parentID>10</parentID>
		<funtionality available="true">
			<loop>
				<name>loop1</name>
			</loop>
			<fork>
				<kind>OR</kind>
			</fork>
			<sub>
				<type>dynamic</type>
			</sub>
		</funtionality>
	</node>
</model>

I'm new to XML and XSLT and I need the XML to be restructured so that the functionality tags occur within the node that it corresponds to. I'm guessing if you know what you are doing a couple of lines would do it but I'm totally clueless. Any help would be appreciated.

Thanks
sillypepper

mhkay · August 18th, 2009, 06:25 PM

I'm guessing a bit at the requirement. Assuming that a <node> is followed by zero or one <function> elements, and that is the one that it "corresponds to", then you want an identity template:

Code:

<xsl:template match="*">
  <xsl:copy>
     <xsl:copy-of select="@*"/>
     <xsl:apply-templates/>
  </xsl:copy>
</xsl:template>

and then overriding templates where special action is needed:

Code:

<xsl:template match="functionality">
  <xsl:copy>
     <xsl:copy-of select="@*"/>
     <xsl:apply-templates/>
     <xsl:copy-of select="../following-sibling::*[1][self::function]/*"/>
  </xsl:copy>
</xsl:template>

<xsl:template match="function"/>

Read that path expression as "select the first following sibling element of the parent of this node, provided it is a function element, and then copy its children".

sillypepper · August 18th, 2009, 07:01 PM

Thanks for the quick reply.

Actually the file will have all nodes followed by function elements. See below for an idea (I've left the details out as they are in the original post).

Code:

<node></node>
<node></node>
<node></node>
<node></node>
<node></node>
<function></function>
<function></function>

There is no order to the nodes or function elements. Each node can have at most one function element associated with it or none at all. Also each function element will be associated with only one node. The nodename attribute in the function element identifies what node it should be restructured into. All nodenames will be unique.

I need to restructure using nodename to determine the place of the functionality. The functionality element attribute is set to true if a function element is associated with it.

I'm sorry for the stupid questions. I'm totally new to xml xslt and I just need it for this one thing.

Thanks

Martin Honnen · August 19th, 2009, 06:23 AM

Note that your posted XML sample seems to have typos in element names like 'funtionality'. So I first corrected the XML input to have consistent spelling:

Code:

<model>
    <concept name="example" uniqueID="10"/>
    <node>
        <name>StratA</name>
        <uniqueID>11</uniqueID>
        <class>static</class>
        <category>user</category>
        <parent>example</parent>
        <parentID>10</parentID>
        <functionality available="false"/>
    </node>    
    <node>
        <name>TempA</name>
        <uniqueID>14</uniqueID>
        <class>static</class>
        <category>user</category>
        <parent>example</parent>
        <parentID>10</parentID>
        <functionality available="true"/>
    </node>
    <function nodename="TempA">
        <loop>
            <name>loop1</name>
        </loop>
        <fork>
            <kind>OR</kind>
        </fork>
        <sub>
            <type>dynamic</type>
        </sub>
    </function>
</model>

Then this stylesheet

Code:

<xsl:stylesheet
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  version="1.0">
  
  <xsl:output indent="yes"/>
  <xsl:strip-space elements="*"/>
  
  <xsl:key name="k1" match="function" use="@nodename"/>
  
  <xsl:template match="@* | node()">
    <xsl:copy>
      <xsl:apply-templates select="@* | node()"/>
    </xsl:copy>
  </xsl:template>
  
  <xsl:template match="functionality[@available = 'true']">
    <xsl:copy>
      <xsl:apply-templates select="@*"/>
      <xsl:apply-templates select="key('k1', parent::node/name)/node()"/>
    </xsl:copy>
  </xsl:template>
  
  <xsl:template match="function"/>

</xsl:stylesheet>

should do what you want.

sillypepper · August 19th, 2009, 06:50 AM

Thanks. That works a treat. I'm sorry about the typos I was creating a simple example of what I wanted to happen to save posting my huge xml. I've tweaked it for my real XML and it's all good.

Thanks so much.

sillypepper · August 19th, 2009, 06:55 PM

Hopefully, my last silly question.

If I wanted to move

Code:

<function nodename="TempA">
		<loop>
			<name>loop1</name>
		</loop>
		<fork>
			<kind>OR</kind>
		</fork>
		<sub>
			<type>dynamic</type>
		</sub>
</function>

into the correct <node> but not into functionality, what do I need to change to the stylesheet above?

I've tried altering it and ended up with very mixed results but nothing like what I want. I don't know what to change.

Any ideas appreciated.

Thanks

mhkay · August 19th, 2009, 07:08 PM

When your code doesn't work, it's always a good idea to post it, because then we can see what concept you haven't grasped and try to explain it to you. Without that, there's a danger we just post more code which you still don't understand, and that helps no-one.

The basic design of this stylesheet is that it has a default template rule which copies an element and processes its children, and then it has special template rules for elements that need to be handled differently. The design change you are proposing is that it's the "node" element that needs to be handled differently, not the "functionality" node.

sillypepper · August 19th, 2009, 07:54 PM

Hi,

Thanks for the responce. I'm sorry about the lack of code. It's frustrating not being able to do this. I've created a tool that must take the XML output of someone else's work and I need to change it to fit the structure that my system requires(XSLT transformation of XML is the bit that I cannot grasp). The examples I am using are simplified versions of what I need (I didn't want to post huge chunks of code).

I was using the stylesheet above which works well for what I originally specified but I'd like to change it to move <function> all it's attributes and elements to the correct node identified by nodename. The stylesheet is as follows.

Code:

<xsl:stylesheet
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  version="1.0">
  
  <xsl:output indent="yes"/>
  <xsl:strip-space elements="*"/>
  
  <xsl:key name="k1" match="function" use="@nodename"/>
  
  <xsl:template match="@* | node()">
    <xsl:copy>
      <xsl:apply-templates select="@* | node()"/>
    </xsl:copy>
  </xsl:template>
  
  <xsl:template match="functionality[@available = 'true']">
    <xsl:copy>
      <xsl:apply-templates select="@*"/>
      <xsl:apply-templates select="key('k1', parent::node/name)/node()"/>
    </xsl:copy>
  </xsl:template>
  
  <xsl:template match="function"/>

</xsl:stylesheet>

I have two issues one is to move function but not into functionality just into node. I was thinking that <xsl:template match="functionality[@available = 'true']"> would be the line to change to match node or anything but that didn't work. From your comments I'm thinking maybe the change belongs with the first copy function in the stylesheet.

Also the current stylesheet moves the elements of function but not the function tag so I need to address that. I was guessing that may be something to do with parent:: and node() but to be honest, I'm totally lost. I feel like I'm stabbing in the dark.

I'm thinking that instead of tweaking the above stylesheet maybe coming at it again from scratch may be best as the spec is different.

I think I need to learn the basics, although I thought this was the basics.

Thanks for all your help.
ps the choice of <node> tag by me for an example was a bad choice. Too many nodes floating about.

Martin Honnen · August 20th, 2009, 06:33 AM

Here is an adapted stylesheet:

Code:

<xsl:stylesheet
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  version="1.0">
  
  <xsl:output indent="yes"/>
  <xsl:strip-space elements="*"/>
  
  <xsl:key name="k1" match="function" use="@nodename"/>
  
  <xsl:template match="@* | node()">
    <xsl:copy>
      <xsl:apply-templates select="@* | node()"/>
    </xsl:copy>
  </xsl:template>
  
  <xsl:template match="model">
    <xsl:copy>
      <xsl:apply-templates select="@* | node()[not(self::function)]"/>
    </xsl:copy>
  </xsl:template>
  
  <xsl:template match="node[functionality[@available = 'true']]">
    <xsl:copy>
      <xsl:apply-templates select="@* | node()"/>
      <xsl:apply-templates select="key('k1', name)"/>
    </xsl:copy>
  </xsl:template>

</xsl:stylesheet>

Output now is

Code:

<model>
   <concept name="example" uniqueID="10"/>
   <node>
      <name>StratA</name>
      <uniqueID>11</uniqueID>
      <class>static</class>
      <category>user</category>
      <parent>example</parent>
      <parentID>10</parentID>
      <functionality available="false"/>
   </node>
   <node>
      <name>TempA</name>
      <uniqueID>14</uniqueID>
      <class>static</class>
      <category>user</category>
      <parent>example</parent>
      <parentID>10</parentID>
      <functionality available="true"/>
      <function nodename="TempA">
         <loop>
            <name>loop1</name>
         </loop>
         <fork>
            <kind>OR</kind>
         </fork>
         <sub>
            <type>dynamic</type>
         </sub>
      </function>
   </node>
</model>

So we now have one template for 'model' elements that ensure all nodes besides the function elements are processed and we have a template for 'node' elements with a child element 'functionality' where the 'available' attribute is true where we ensure that the corresponding 'function' element is processed. As the only other template we have is the so called identity transformation we are basically copying the 'function' element.