Recursive data structure example or help

[Dataman9]

This XML newbie is looking for some advice on how ot work with bill-of-material type data structures in XML, where a part element is a parent another another part element, etc:

<Part> (assembly)
<Part> (sub-assembly)
<Part> (component)

I'm thinking that the schema would consist of a Part element that contained a ParentPart attribute similiar to a relation DB solution:

<Parts>
<Part ParentPart=&quot;PartB&quot;>PartD</Part>
<Part ParentPart=&quot;PartB&quot;>PartC</Part>
<Part ParentPart=&quot;PartA&quot;>PartB</Part>
<Part ParentPart=&quot;Top&quot;>PartA</Part>
</Parts>

The next problem I have is how to present this data in it's hierarchically structure with a template. I'm guessing that it would need to select where the ParentPart=&quot;Top&quot; and then apply stylesheets with the Part name passed as a parameter - ParentPart = @Part.

This would need to work recursively since the number of levels in the hierarchy are unknown.

Could anyone steer me in the correct direction or post any examples of working with recursive data structures?

Thank you for your help,
Gary

 

[Mike42]

You can also define the data to be recursive.

Example Schema:

<?xml version=&quot;1.0&quot; encoding=&quot;ISO-8859-15&quot;?>
<xs:schema xmlns:xs=&quot;[URL unfurl="true"]http://www.w3.org/2001/XMLSchema&quot;[/URL] elementFormDefault=&quot;qualified&quot;>
	<xs:complexType name=&quot;PartType&quot;>
		<xs:sequence>
			<xs:element name=&quot;Part&quot; type=&quot;PartType&quot; minOccurs=&quot;0&quot; maxOccurs=&quot;unbounded&quot;/>
		</xs:sequence>
		<xs:attribute name=&quot;id&quot; type=&quot;xs:string&quot; use=&quot;required&quot;/>
	</xs:complexType>
	<xs:element name=&quot;Parts&quot;>
		<xs:complexType>
			<xs:sequence>
				<xs:element name=&quot;Part&quot; type=&quot;PartType&quot; maxOccurs=&quot;unbounded&quot;/>
			</xs:sequence>
		</xs:complexType>
	</xs:element>
</xs:schema>

This will allow easy XPath access to the structure via axis selection.

Example xml:

<Parts>
   <Part id=&quot;PartA&quot;>
      <Part id=&quot;SubPartB&quot;>
         <Part id=&quot;SubSubPartA&quot;/>
      </Part>
      <Part id=&quot;SubPartC&quot;/>
   </Part>
   <Part id=&quot;PartB&quot;>
      <Part id=&quot;SubPartD&quot;/>
   </Part>
</Parts>

Now you can e.g. select all Part children of PartA via XPath expression

//Part[@id='PartA']/descendant::Part

this will select

   <Part id=&quot;SubPartB&quot;/>
   <Part id=&quot;SubSubPartA&quot;/>
   <Part id=&quot;SubPartC&quot;/>