Can E4X Get Attribute of a Parent Node Based on Attribute of a Child At Any Level?

Question

Hi,

I'm struggling with some E4X and hope you can help.

Here's my XML structure:

<xml>
    <node type="bar">
        <subnode id="4">
         <subnode id="5"/>
        </subnode> 
        <subnode id="6"/>
    </node>
    <node type="foo">
        <subnode id="7">
         <subnode id="8">
          <subnode id="9"/>
         </subnode>
        </subnode>
        <subnode id="10"/>
    </node>
</xml>

As you can see there are multiple "nodes" which can have unlimited child levels of "subnode" elements.

What I want to do is find @type attribute of the "node" for any given "subnode", based on its @id attribute. For example, if I have an id of 9 then I want to return the type="foo" from above.

The E4X I have come up with, but which fails is:

xml.node.(subnode.(@id == '8')).@type

I can kind of see why it doesn't work. What would make more sense is the following but the syntax fails (in AS3):

xml.node.(..subnode.(@id == '8')).@type

Anybody?

Jake

Answer 1

Having given up on E4X I used a "hack" and did it in ActionScript instead. Here's how:

var p:XML = xml..subnode.(attribute('id').toLowerCase() === "8")[0];

//Traverse back up to the parent "node"           
while ( p.name().toString() === "subnode" ) {
    p = p.parent();
}

Alert.show(p.@type); //Should say "foo"

Seems a mess though. Would still be interested in any plain E4X solution.

Jake

Answer 2

Try this

for each(var node:XML in xml.node)
{
    var subnodes:XMLList = node..subnode;
    if(subnodes.(@id == '9').length() != 0)
        return node.@type;
}

EDIT: Even this should work:

if(node..subnode.(@id == '9').length() != 0)

Answer 3

You should be able to get the type value using this E4X:

xml.node.(descendants("subnode")[email protected]("8")).@type;