GetDetailsOf returns property name instead of value (delphi 2007)

Question

I have never needed to do much COM, so have almost no experience with it. Nearly all of the documentation (certainly from MS) does not include Delphi examples. In my code example, I can't see where I'm going wrong. The code was borrowed from snippets found in several locations on the web. Some were VB. I only found one thread for Free Pascal, and it was incomplete. This runs, but shows displays the same string for both name and value. I hope someone can see what I'm missing. I think the problem is with the line that reads:

PropValue := OleFolder.GetDetailsOf(OleFolderItem, i);

I don't know if I need to do something to initialize "OleFolderItem".

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, ActiveX, ComObj, StdCtrls, ExtCtrls;

type
TForm1 = class(TForm)
 pnl1: TPanel;
 btn1: TButton;
 mmo1: TMemo;
 OpenDialog1: TOpenDialog;
 procedure btn1Click(Sender: TObject);
 procedure getExtdProps(AFileName: string);
private
 { Private declarations }
public
 { Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

Procedure TForm1.getExtdProps(AFileName: string);
var
Shell : Variant;
OleFolder : OleVariant;
OleFolderItem: OleVariant;
PropName, PropValue: string;
i: integer;
begin
Shell := CreateOleObject('Shell.Application');
OleFolder := Shell.Namespace(ExtractFilePath(AFileName));
i := 0;
PropName := 'Not an EmptyStr'; //So the next loop will work.
while PropName <> EmptyStr do
begin
 PropName  := OleFolder.GetDetailsOf(null, i); {null gets the name}
 PropValue := OleFolder.GetDetailsOf(OleFolderItem, i); { OleFolderItem should get the value }
 if PropName <> '' then
   mmo1.Lines.Add(PropName + ':  ' + PropValue);
 inc(i);
end;
end;

procedure TForm1.btn1Click(Sender: TObject);
begin
if OpenDialog1.Execute then
begin
 GetExtdProps(OpenDialog1.FileName);
end;
end;

end.

Answer 1

Try this complete example :

unit GetDetailsOfDemoMain;

interface

uses
    Winapi.Windows, Winapi.Messages,
    System.SysUtils, System.Variants, System.Win.ComObj, System.Classes,
    Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;

type
    TForm1 = class(TForm)
        Button1: TButton;
        OpenDialog1: TOpenDialog;
        Memo1: TMemo;
        procedure Button1Click(Sender: TObject);
    private
        procedure GetExtdProps(AFileName: string);
    end;

var
    Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.GetExtdProps(AFileName: string);
var
    Shell         : Variant;
    OleFolder     : OleVariant;
    OleFolderItem : OleVariant;
    ForlderName   : String;
    PropName      : String;
    PropValue     : string;
    I             : integer;
begin
    Shell         := CreateOleObject('Shell.Application');
    OleFolder     := Shell.Namespace(ExtractFilePath(AFileName));
    OleFolderItem := OleFolder.ParseName(ExtractFileName(AFileName));
    for I := 0 to 999 do begin
        PropName  := OleFolder.GetDetailsOf(null, i);
        PropValue := OleFolder.GetDetailsOf(OleFolderItem , I);
        if (PropName <> '') and (PropValue <> '') then
            Memo1.Lines.Add(Format('%3d) %-30s: %s',
                                   [I, PropName, PropValue]));
    end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
    if OpenDialog1.Execute then
        GetExtdProps(OpenDialog1.FileName);
end;

end.

DFM file:

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 441
  ClientWidth = 624
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -12
  Font.Name = 'Segoe UI'
  Font.Style = []
  PixelsPerInch = 96
  DesignSize = (
    624
    441)
  TextHeight = 15
  object Button1: TButton
    Left = 40
    Top = 32
    Width = 75
    Height = 25
    Caption = 'Button1'
    TabOrder = 0
    OnClick = Button1Click
  end
  object Memo1: TMemo
    Left = 8
    Top = 72
    Width = 609
    Height = 361
    Anchors = [akLeft, akTop, akRight, akBottom]
    Font.Charset = DEFAULT_CHARSET
    Font.Color = clWindowText
    Font.Height = -12
    Font.Name = 'Consolas'
    Font.Style = []
    ParentFont = False
    ScrollBars = ssBoth
    TabOrder = 1
  end
  object OpenDialog1: TOpenDialog
    Left = 48
    Top = 88
  end
end