Registry ReadString method is not working in Windows 7 in Delphi 7

Question

The following code sample used to return me windows id before, but now it doesn't work, and returns empty string, dunno why.

  function GetWindowsID: string;
  var
    Registry: TRegistry;
    str:string;
  begin
    Registry := TRegistry.Create(KEY_WRITE);
    try
      Registry.Lazywrite := false;
      Registry.RootKey := HKEY_LOCAL_MACHINE;
   //   Registry.RootKey := HKEY_CURRENT_USER;
      if CheckForWinNT = true then
       Begin
       if not Registry.OpenKeyReadOnly('\Software\Microsoft\Windows NT\CurrentVersion') then showmessagE('cant open');
       end
      else
        Registry.OpenKeyReadOnly('\Software\Microsoft\Windows\CurrentVersion');
      str := Registry.ReadString('ProductId');
      result:=str;
      Registry.CloseKey;
    finally
      Registry.Free;
    end; // try..finally
  end;

Anybody can help?

Answer 1

That is because the virtualized key '\Software\Wow6432Node\Microsoft\Windows NT\CurrentVersion\' doesn't contain the 'ProductID' item.

Modify your code to create the TRegistry instance with

Registry := TRegistry.Create(KEY_WRITE OR KEY_WOW64_64KEY);

where KEY_WOW64_64KEY = $0100. That will give you the expected result.

Alternatively, use DSiWin32 and call

DSiReadRegistry('\Software\Microsoft\Windows NT\CurrentVersion', 
  'ProductID', '', HKEY_LOCAL_MACHINE, KEY_QUERY_VALUE OR KEY_WOW64_64KEY);