Referencing a file in Xojo Cloud

Xojo Cloud
1

Simple story, not so obvious answer.

I have a Console app uploaded to my Xojo Cloud. The app is run from a Shell, which a Web App provides. Thank you Greg for helping that functionality come to pass.

The console App is a Linux build and lives in the Shared_Documents folder, in a folder named TMW-Alpha. It references local files, in particular a log file (ProjectLog.txt) in the same folder as the console app. This folder also contains the console app Libs folder.

Now if you are a hardworking, decent person, you might think that you reference this TMW-Alpha folder as a subfolder within SpecialFolder.SharedDocuments … and you would be wrong. That does not work (i.e. nil object exception). A Linux build, even though it runs within the Xojo Cloud environment, cannot find the Shared_Documents folder of your Xojo Cloud using any SpecialFolder notation that I have found. If others know of secret sauce which will divulge this folder easily, please share !

My solution is sufficiently ugly that I have thought to share it here, so that others may read, and weep.

[code]dim fA, fA2, fA3, fA4, fA5, fB as folderItem

if debugBuild then
return SpecialFolder.Desktop.child(“Text-Me-Web-Folder”).child(“ProjectAlpha”)

else
fA = SpecialFolder.CurrentWorkingDirectory

if fA.exists = false then return nil

fA2 = fA.child("home")
if fA2.exists = false then return nil

fA3 = fA2.child("sites")
if fA3.exists = false then return nil

fA4 = fA3.child("www.example.com")
if fA4.exists = false then return nil

fA5 = fA4.child("Shared_Documents")
if fA5.exists = false then return nil

fB = fA5.child("TMW-Alpha")
if fB.exists = false then return nil

return fB[/code]

This ugliness will return a folderItem that is either nil, or points to the desired location ( a subfolder named TMW-Alpha within the Shared_Documents folder).

Hope this will save others in their search for their folders.

Regards,
Tony Barry
Sydney

2

Code like this should work to find TMW-Alpha:

  dim f as FolderItem = SpecialFolder.SharedDocuments.child("TMW-Alpha")
  
  if f.Exists then
    MsgBox "It's there."
  else
    MsgBox "Couldn't find it."
  end if
3

My mistake (thanks Paul!) - the code that I posted works for a web app but not for a console app. This code should work for a console app:

Dim f As FolderItem = App.ExecutableFile.Parent.Child("TMW-Alpha")
4

Thank you Jason for this short cut. Much appreciated.

5

Now a perplexing observation.

I use a Shell within my web app to launch my Console app.
If I add the path to the Console app to the PATH environment variable, then the Console app launches and does its work.

If I launch it via the following Shell command, it does not work as expected.

cd /home/sites/www.example.com/Shared_Documents/TMW-Alpha; pwd; ./PretendParse

When I run this, the Shell correctly indicates (from the pwd command) that it is pointing at the TMW-Alpha folder. And PretendParse runs; however it is unable to “find” its log file, which is in the same folder, and exits with an error which alerts me to the fact.

Note I can remove the pwd command and get the same result.

Any thoughts on why the PATH addition works, but the cd command set does not ?

Here is the function that fails:-

[code] dim log as TextOutputStream
dim fBase, fLog as folderItem
dim d as date

d = new date

fBase = getBaseFolder()
if fBase = nil then
return false
end if

fLog = fBase.child(“ProjectLog.txt”)
if fLog.exists = false then
return false
end if

if fLog.exists = false then
log = TextOutputStream.Create(fLog)
else
log = TextOutputStream.Append(fLog)
end if

if log = nil then

return false

end if

log.WriteLine d.SQLDateTime + " | " + datum

log.Close

return true[/code]

The function getBaseFolder is described above, but reproduced here for ease of understanding:-

Dim f As FolderItem = App.ExecutableFile.Parent.Child("TMW-Alpha")

Regards,
Tony Barry
Sydney, Australia

6

Are you sure that it’s not finding it? You’ve got three conditions which return False from baseFolder being nil, to the file not existing, to log being Nil.

Observations:

if fLog.exists = false then Return False End If

If the log file doesn’t exist, you return False without creating it.

if fLog.exists = false then log = TextOutputStream.Create(fLog) else log = TextOutputStream.Append(fLog) end if

This section of code will throw an ioexception if there’s an error and not simply return Nil.

7

Hi Greg,

Yes indeed. A poor showing on my part there.

That was definitely not one of my better efforts.

Thank you for your observations. I shall read over my code again and try to observe where I have been similarly stupid.

Regards,
Tony Barry
Sydney, Australia