Fun with XPath: Combining many fields in a query.

This is one of those things that are so obvious I felt like kicking myself when I realised how to do it.

First, some XML:

<?xml version="1.0" standalone="yes"?> 
<styling_rules > 
  <rule column="NAME" > 
    <features style="MAG:C.WASSNAME.CHOCOLATE"> NAME='T BAR BOO' </features> 
    <label column="NAME" style="MAG:T.STREET NAME">1</label> 
  </rule> 
  <rule column="NAME" > 
    <features style="MAG:C.WASSNAME.CORAL"> NAME='UP A CREEK' </features> 
    <label column="NAME" style="MAG:T.STREET NAME">1</label> 
  </rule> 
  <rule column="NAME" > 
    <features style="MAG:C.WASSNAME.CORNFLOWERBLUE"> NAME='UNHAPPY VALLEY' </features> 
    <label column="NAME" style="MAG:T.STREET NAME">1</label> 
  </rule> 
</styling_rules>

This has been anonomised for the purposes of this discussion. The tool that uses the data flattens the two elements inside the rule element out so fine. I needed an XPath that would get me a particular rule node so I can manipulate it.

I put my SQL head on and looked for two sets that I could combine:

xPath = "/styling_rules/rule[@column='NAME']/features[@style='MAG:C.WASSNAME.CORNFLOWERBLUE' " + 
       " and /styling_rules/rule[@column='NAME']/features/[text() = \"  NAME='UNHAPPY VALLEY' \" " ;

Nah, don't even go there, it doesn't choke but it doesn't do anything. Instead think directory path and the *nix find command comined together:

xPath = "/styling_rules/rule[@column='NAME']/features[@style='MAG:C.WASSNAME.CORNFLOWERBLUE' " + 
        " and ./text() = \" NAME='UNHAPPY VALLEY' \" ]/parent::" ;

This should get me the whole node and I can then update the elements in it to my heart's content.

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