Remove empty <ul> nodes from IXMLDOMDOCUMENT in Delphi

Question

I have many xml nodes in an xmldocument. I want to remove all the empty <ul> nodes. How can I accomplish this?

Here is a snippet:

  <li>
    <a href="javascript:void(0);">Level 1</a>
    <ul id="subject19">
      <li>
        <a href="javascript:void(0);">Level 2</a>
        <ul id="subject20">
          <li>
            <a href="javascript:void(0);">Level 3</a>
            <ul id="subject21"/>
          </li>
        </ul>
      </li>
    </ul>
  </li>

I need to remove <ul id="subject21"/>

Answer 1

You can use a simple recursion. Here is an example how:

procedure ScanAndRemove(aNode: IXMLNode);
var
  i: Integer;
  childNode: IXMLNode;
begin
  i := 0;
  while i < aNode.ChildNodes.Count do
  begin
    childNode := aNode.ChildNodes[i];
    if (childNode.NodeName = 'ul') and (childNode.ChildNodes.Count = 0) then
      aNode.ChildNodes.Remove(childNode) else
      begin
        ScanAndRemove(childNode);
        Inc(i);
      end;
  end;
end;

And just pass the document root element:

procedure Cleanup;
var
  xmlDoc: IXMLDocument;
begin
  xmlDoc := TXMLDocument.Create(nil);
  try
    xmlDoc.LoadFromXML('...');
    ScanAndRemove(xmlDoc.DocumentElement);
    // now xmlDoc contains the desired result
  finally
    xmlDoc := nil;
  end;
end;

EDIT The recursive function will remove a node without children, but containing a value. Eg:

<ul>
  blabla
</ul>

If you want the opposite, you should add one more check - ie:

if (childNode.NodeName = 'ul') and 
  (childNode.ChildNodes.Count = 0) and 
  (VarToStrDef(childNode.NodeValue, '') = '') then
  ... 

Or this way - https://stackoverflow.com/a/9673869/3962893