Friday, July 4, 2014

Choose the Right Folder for Your Application Data

I'm in the process of updating an older program that will now use a local database. I followed my typical "old school" habits and quietly went about my way thinking "I'll just plop the database in a folder called Data that resides in the same location as the exe file. No big deal."

I figured, I'll just use the reliable ExtractFilePath(Application.ExeName) to get the location of where this Data folder needs to go. Right?


I had forgotten to think about how Delphi's "debug" and "release" paths will play into this scenario. Not to mention 32Bit and 64Bit targets. I'm only focused on creating a Windows product at the moment, so for me this means there are a minimum of five paths:


I know I could use "Post-Build" commands (Project > Options > Build Events) to make sure the files are copied from the $(PROJECTDIR) to the $(OUTPUTDIR). However, I was thinking that this is not a very efficient way to go about it. Did I really want to have five copies of a 140MB database cluttering up my hard drive. The answer is no.

So I posed the question "Looking for best practice for using single-user local database." to the Delphi Community on Google+ (

I received several comments and the consensus was to use an application specific subfolder of CommonAppData. Fair enough. CommonAppData it is. What the heck is CommonAppData?

I tend to be a "Show Me" guy I decided to dive into this head long and found out that CommonAppData actually refers to the folder called C:\ProgramData.

Then I wondered what all the other "AppData" type folders were. So I wrote a simple little program to help figure this out. It turns out there are 17 different AppData folders on my computer. I've included a copy of my program for you to use.

AppData Only: Sorted by Path Column

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Paths'
  ClientHeight = 411
  ClientWidth = 804
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  OnResize = FormResize
  OnShow = FormShow
  DesignSize = (
  PixelsPerInch = 96
  TextHeight = 13
  object StringGrid1: TStringGrid
    Left = 16
    Top = 39
    Width = 772
    Height = 354
    Anchors = [akLeft, akTop, akRight, akBottom]
    ColCount = 3
    FixedCols = 0
    Font.Charset = DEFAULT_CHARSET
    Font.Color = clWindowText
    Font.Height = -11
    Font.Name = 'Tahoma'
    Font.Style = []
    Options = [goFixedVertLine, goFixedHorzLine, goVertLine, goHorzLine, goRangeSelect, goFixedRowClick]
    ParentFont = False
    TabOrder = 0
    OnFixedCellClick = StringGrid1FixedCellClick
  object Button1: TButton
    Left = 16
    Top = 8
    Width = 75
    Height = 25
    Caption = 'Close'
    TabOrder = 1
    OnClick = Button1Click
  object Button2: TButton
    Left = 97
    Top = 8
    Width = 75
    Height = 25
    Caption = 'Get Folders'
    TabOrder = 2
    OnClick = Button2Click
  object CheckBox1: TCheckBox
    Left = 184
    Top = 12
    Width = 97
    Height = 17
    Caption = 'AppData Only'
    TabOrder = 3
    OnClick = Button2Click


Enjoy - Semper Fi,
Gunny Mike