Uninstall when running inno setup with application already installed

Question

I have just started using inno setup, and it seems to work well. However, when I run the installer with the app already installed it reinstalls. I would like to give the user to uninstall. Is this possible, and if so, how can it be done?

To be specific, I have written a game for a homework assignment. I made an installer using inno setup. The app installs fine and can be uninstalled using the control panel, but my professor would like to be able to uninstall the application by re-running the installer and choosing an uninstall option. This will save him time since he has about 50 of these assignments to mark.

Thanks,

Gerry

Answer 1

The next script will make the following options form when the application is already installed on the target system when the setup is started:

When the user clicks Repair button, the setup is normally started. When user clicks the Uninstall button, the previously installed application is uninstalled. When user closes that form, nothing happens.

Here is the script (don't forget to specify, ideally some unique, value for the AppId setup directive in your script):

[Setup]
AppName=My Program
AppVersion=1.5
AppId=1C9FAC66-219F-445B-8863-20DEAF8BB5CC
DefaultDirName={pf}\My Program
OutputDir=userdocs:Inno Setup Examples Output

[CustomMessages]
OptionsFormCaption=Setup options...
RepairButtonCaption=Repair
UninstallButtonCaption=Uninstall

[Code]
const
  mrRepair = 100;
  mrUninstall = 101;

function ShowOptionsForm: TModalResult;
var
  OptionsForm: TSetupForm;
  RepairButton: TNewButton;
  UninstallButton: TNewButton;
begin
  Result := mrNone;
  OptionsForm := CreateCustomForm;
  try
    OptionsForm.Width := 220;
    OptionsForm.Caption := ExpandConstant('{cm:OptionsFormCaption}');
    OptionsForm.Position := poScreenCenter;

    RepairButton := TNewButton.Create(OptionsForm);
    RepairButton.Parent := OptionsForm;
    RepairButton.Left := 8;
    RepairButton.Top := 8;
    RepairButton.Width := OptionsForm.ClientWidth - 16;
    RepairButton.Caption := ExpandConstant('{cm:RepairButtonCaption}');
    RepairButton.ModalResult := mrRepair;

    UninstallButton := TNewButton.Create(OptionsForm);
    UninstallButton.Parent := OptionsForm;
    UninstallButton.Left := 8;
    UninstallButton.Top := RepairButton.Top + RepairButton.Height + 8;
    UninstallButton.Width := OptionsForm.ClientWidth - 16;
    UninstallButton.Caption := ExpandConstant('{cm:UninstallButtonCaption}');
    UninstallButton.ModalResult := mrUninstall;

    OptionsForm.ClientHeight := RepairButton.Height + UninstallButton.Height + 24;
    Result := OptionsForm.ShowModal;
  finally
    OptionsForm.Free;
  end;
end;

function GetUninstallerPath: string;
var
  RegKey: string;
begin
  Result := '';
  RegKey := Format('%s\%s_is1', ['Software\Microsoft\Windows\CurrentVersion\Uninstall', 
    '{#emit SetupSetting("AppId")}']);
  if not RegQueryStringValue(HKEY_LOCAL_MACHINE, RegKey, 'UninstallString', Result) then
    RegQueryStringValue(HKEY_CURRENT_USER, RegKey, 'UninstallString', Result);
end;

function InitializeSetup: Boolean;
var
  UninstPath: string;
  ResultCode: Integer;  
begin
  Result := True;
  UninstPath := RemoveQuotes(GetUninstallerPath);
  if UninstPath <> '' then
  begin
    case ShowOptionsForm of
      mrRepair: Result := True;
      mrUninstall: 
      begin
        Result := False;
        if not Exec(UninstPath, '', '', SW_SHOW, ewNoWait, ResultCode) then
          MsgBox(FmtMessage(SetupMessage(msgUninstallOpenError), [UninstPath]), mbError, MB_OK);
      end;
    else
      Result := False;
    end;
  end;
end;

Answer 2

For some reason your code

RegKey := Format('%s\%s_is1', ['Software\Microsoft\Windows\CurrentVersion\Uninstall', 
    '{#emit SetupSetting("AppId")}']);

returned an extra { to the _is1 value. I didn't had the time to check why or where i was wrong in my implementation, all i confirm is that my installer works with the

RegKey := ExpandConstant('Software\Microsoft\Windows\CurrentVersion\Uninstall\{#emit SetupSetting("AppId")}_is1');

alternate.

Hope it helps.

Thank you for the code sample.