Delphi - Checking for Dropbox on OSX

Question

I am writing a multi-platform application using Delphi 10.2 Tokyo Firemonkey. One of the things I need to check is if Dropbox exists on the computer. For this I need to check for the presence of an info.json file and then process that json file to get the path of the Dropbox folder.

I wrote this function to check for the presence of Dropbox:

class function TUtilityMac.DropboxExists: Boolean;
var
  infojsonpath: String;
begin
  Result:=false;
  infojsonpath:='~/.dropbox/info.json';
  if not FileExists (infojsonpath, True) then
    exit;
  Result:=true;
end;

But when I run this on a Mac (that has Dropbox installed), the FileExists function returns false (regardless of the second parameter being True or False). If I open a terminal window and do a cd ~/.dropbox and then a dir, I do see the info.json file there.

Any thoughts around what I am missing? Would appreciate any pointers regarding this...

Are you sure you really need this curvy double negation logic? `DropboxExists := FileExists('~/.dropbox/info.json', True)` — Free Consulting, Apr 18 '17 at 10:45
That is just a standalone code snippet to show the issue - not the actual code in my app. In my actual code I find the file and parse the json to get the actual location of the Dropbox folder. But I agree with you, it could have been as compact as you suggest :) — Rohit, Apr 18 '17 at 10:48
If you remove the `FileExists()` check, are you able to load the file using the same path? If so, then just forget `FileExists()` and always load the file unconditionally and handle any load errors as needed. — Remy Lebeau, Apr 18 '17 at 14:52
Thanks @RemyLebeau - will give that a try and let you know how it works out... — Rohit, Apr 19 '17 at 08:57
@RemyLebeau - I got a `EFileNotFoundException` when I tried to load the file. But the file exists. Any idea what might be going on? — Rohit, Apr 19 '17 at 14:07
I figured it out - will respond with an answer to the question... — Rohit, Apr 19 '17 at 14:49

score 2 · Accepted Answer · edited Apr 19 '17 at 16:35

Well - I figured it out (by trial and error).

The issue is that when we use the literal ~/.dropbox, Delphi is looking for that precise folder, which of course does not exist. The ~ on OSX refers to the user's directory (e.g. in my case it would be /Users/rohit). So if I replaced the ~ with /Users/rohit, the application found the file and everything worked as expected.

Just for completeness of the answer, the function can be written as:

class function TUtilityMac.DropboxExists: Boolean;
var
  infojsonpath: String;
begin
  infojsonpath := IncludeTrailingPathDelimiter(GetHomePath) + '.dropbox/info.json';
  Result := FileExists(infojsonpath, True);
end;

Note that the key here is to use GetHomePath() to get the current user's directory on OSX; on Windows, it returns the current user's %APPDATA% folder.

Delphi - Checking for Dropbox on OSX

1 Answers1