UniGUIDialogs ShowMessage not displayed

[misc]

I have an application that uses ZeosDb to access a mySQL database. When mySQL is restarted on the server, the app looses connection, and "Dataset.Active:= true;" raises an "ODBC call failed" exception, passing into the catch-all below:

procedure TUniServerModule.UniGUIServerModuleException(Sender: TUniGUIMainModule; AException: Exception; var Handled: Boolean);
begin
  if LikeList(AException.Message, ['*odbc*', '*sql server*']) then begin
    ShowMessage(rsDBReconnect);  //<--not shown

  end else
    ShowMessage(Sender.Name + ': ' + AException.Message);  //<--shown

  Handled:= true;
end;

Problem 1: the red message above is not displayed, even though we definitely pass here in debug mode. If a non-odbc error is encountered, the blue message is shown.

 

Problem 2: after this event, all uniGUI menus are gone and the app does not really work anymore

 

My guess is, that the exception itsself already puts the application into some strange state, where things like menus & dialogs dont work anymore.

 

Any ideas how I can handle this?

 

[Farshad Mohajeri]

OnException event is only for non-visual code.

ShowMessage() and etc. will not work here.  It may occasionally work, but as I said this exception not always  run synchronous with visual GUI.

 

If you want to catch the exception do it where you set DataSet.Active := True;

[misc]

Hello Farshad,

 

as I am working heavily with databases, it is unfortunately very hard to catch every DB exception where it occurs. Also, when an exception occurs the app goes into some strange crash state, where the menus and some of the controls no longer work. Do you know anything about this? Why does it happen and how can I prevent it? Or in other words: if a database connection exception occurs (Zeos controls), why do the unigui menus no longer work. What does one thing have to do with the other?!

 

And how can I handle the message problem? Any tricks? If I could show a message in the general UniGUIServerModuleException, then I could ask the user to restart the app, or even do it for him. At the moment, due to the crashed state after an exception, the user experiences the uniGUI application as unstable and with undetermined outcome.

[Farshad Mohajeri]

why do the unigui menus no longer work.

 

 

What does the above in technical terms mean?

[misc]

They are empty, ie only a tiny square pops up. I suppose that means they are empty.

 

Or in not so technical terms: It seems the DB connection exception eats up the unigui menu items ;-)

[Farshad Mohajeri]

Which menu items? Those in web app?

[misc]

I've attached a screenshot to illustrate the problem.

 

Thanks for the effort.

[misc]

I've attached a screenshot to illustrate the problem.

 

Thanks for the effort.

[Oliver Morsch]

Read post #2 from Farshad ?!

[Farshad Mohajeri]

Unigui version?

[misc]

@ Farshad: uniGUI 0.95.0.1044

 

@ Oliver: sorry, can you rephrase?

[Farshad Mohajeri]

@ Farshad: uniGUI 0.95.0.1044

 

Can you prepare a test case?

[Farshad Mohajeri]

Another question:

 

Will this problem persist if you don't handle OnException event at all?

[Oliver Morsch]

@ Oliver: sorry, can you rephrase?

 

Farshad wrote in post #2:

 

OnException event is only for non-visual code.

ShowMessage() and etc. will not work here.

...

 

I think ServerModule is another thread/context and something like ShowMessage() there will produce other problems.

[misc]

DelphiDeveloper helped me find the problem, which is also described here:
http://www.sencha.com/forum/showthread.php?260320-4.2.0-Ext.suspendLayouts-causes-a-menu-to-be-not-rendered

 

I used UniSession.AddJS('Ext.suspendLayouts()') in heavy control creation in order to eliminate unnecessary control painting, and in unhandled exceptions I dont reach UniSession.AddJS('Ext.resumeLayouts(true)');

 

So solved this, not an uniGUI bug, but the global exception problem stll persists: How do I create a global exception handler?

 

I tried this, but it is not called at all:
 

procedure TMainForm.UniFormCreate(Sender: TObject);
begin
  Application.OnException:= AppException;
end;

procedure TMainForm.AppException(Sender: TObject; E: Exception);
//not called!
begin
  UniGUIDialogs.ShowMessage(E.Message);
end;

[Farshad Mohajeri]

UniGUIServerModuleException() is the global exception handler.

[Farshad Mohajeri]

Normally all exceptions are handled by framework and an alert is displayed. I checked the code and couldn't see why your message is not shown.

 

Is it an ISAPI or standalone app?