Pascal (Lazarus/Delphi)

Removing / Deleting Child Nodes from XML

See more XML Examples

Demonstrates various methods for removing child nodes from an XML document.

The input XML, available at http://www.chilkatsoft.com/data/fruit.xml, is this:

<root>
    <fruit color="red">apple</fruit>
    <fruit color="green">pear</fruit>
    <veg color="orange">carrot</veg>
    <meat animal="cow">beef</meat>
    <xyz>
        <fruit color="blue">blueberry</fruit>
        <veg color="green">broccoli</veg>
    </xyz>
    <fruit color="purple">grape</fruit>
    <cheese color="yellow">cheddar</cheese>
</root>

Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Xml;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  xml: TXml;
  xyz: TXml;

begin
  success := False;

  xml := TXml.Create;

  //  The sample input XML is available at http://www.chilkatsoft.com/data/fruit.xml
  success := xml.LoadXmlFile('fruit.xml');
  if (success <> True) then
    begin
      WriteLn(xml.LastErrorText);
      Exit;
    end;

  //  The RemoveChild method removes (discards) all direct
  //  children having the specified tag:
  xml.RemoveChild('fruit');

  //  Show the resulting XML:
  WriteLn('Result with all direct children having a tag equal to "fruit" removed:');
  WriteLn(xml.GetXml());

  //  The XML with the "fruit" direct children removed is shown below:
  //  Notice that the "fruit" node beneath "xyz" was not removed.
  //  This correct because it was not a direct child of the calling node.

  //  <root>
  //      <veg color="orange">carrot</veg>
  //      <meat animal="cow">beef</meat>
  //      <xyz>
  //          <fruit color="blue">blueberry</fruit>
  //          <veg color="green">broccoli</veg>
  //      </xyz>
  //      <cheese color="yellow">cheddar</cheese>
  //  </root>

  //  --------------------------------------------------------------------------
  //  Restore the original XML:
  success := xml.LoadXmlFile('fruit.xml');

  //  The RemoveChildWithContent method removes the child
  //  having the exact content specified, regardless of the tag.  
  //  For example:
  xml.RemoveChildWithContent('pear');

  //  Show the resulting XML:
  WriteLn('Result with the node containing "pear" removed:');
  WriteLn(xml.GetXml());

  //  --------------------------------------------------------------------------
  //  Restore the original XML:
  success := xml.LoadXmlFile('fruit.xml');

  //  The RemoveChildByIndex method removes the Nth direct
  //  child.  Indexing begins at 0.  The "xyz" child is at index 4:
  xml.RemoveChildByIndex(4);

  //  Show the resulting XML:
  //  Notice that the entire "xyz" subtree is removed.
  WriteLn('Result with the node at index 4 removed:');
  WriteLn(xml.GetXml());

  //  --------------------------------------------------------------------------
  //  Restore the original XML:
  success := xml.LoadXmlFile('fruit.xml');

  //  Navigate to the node with tag "xyz";
  xyz := xml.FindChild('xyz');

  //  Remove the "xyz" subtree making it it's own XML document
  //  with the "xyz" node at the root:
  xyz.RemoveFromTree();

  //  Show both XML documents:
  WriteLn(xyz.GetXml());
  WriteLn(xml.GetXml());

  //  Also, the TreeId property is an integer value assigned
  //  to nodes in an XML document.  All nodes belonging to
  //  the same XML document will have the same TreeId.
  //  Notice that the "xyz" node now has a different TreeId:
  WriteLn('xyz TreeId = ' + xyz.TreeId);
  WriteLn('xml TreeId = ' + xml.TreeId);

  xyz.Free;


  xml.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.