Nsis Scripting to recognize previous installation directory - scripting

Question

I am trying to recognized the previous installation directory in nsis scripting language using registry.
I found a entry for uninstollation in this registry
HKLM "SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\PaperTrlQBDConnector" "UninstallString"
but the registry value is \xxx\xxxx\PaperTrlQBDConnector\unistall.exe
i want to extract the path without uninstall.exe to a variable.
Function PreDirCheck
# discover if QBD Connector is already installed
ClearErrors
SetRegView 64
ClearErrors
;ReadRegStr $previous_install_dir HKLM "SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\PaperTrlQBDConnector" "PreDir"
;${if} $previous_install_dir == 0
ReadRegStr $previous_install_dir HKLM "SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\PaperTrlQBDConnector" "UninstallString"
;${Endif}
IfErrors done
;sectionsetflags ${sec1} 0
SetAutoClose false
strcpy $INSTDIR $previous_install_dir
MessageBox MB_ICONQUESTION|MB_YesNO|MB_DEFBUTTON2 "Detected previous version in Directory $previous_install_dir $\n Click Yes To update in the existing directory $\n Click No to completely remove PaperTrl SyncManager and install to a new location?" IDYes lbl_abort IDNo lbl_un
lbl_abort:
sectionsetflags ${sec2} 0
Abort ;skip page
lbl_un:
!insertmacro UninstallExisting
sectionsetflags ${sec2} 1
done:
SetAutoClose false
;!insertmacro MUI_PAGE_DIRECTORY
sectionsetflags ${sec2} 1
FunctionEnd
i tried this code but it gives the variable value with the unistall.exe for the path

Answer 1

InstallDirRegKey knows how to remove the .exe if you point it to your UninstallString value. Controlling its reg-view however is not possible.
You can also remove the last path component yourself:
!include "FileFunc.nsh"
Function .onInit
ReadRegStr $0 HK.. ...
${GetParent} "$0" $1
MessageBox MB_OK $1
FunctionEnd