GUIDATA save handles only after exiting callback

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David Nguyen
David Nguyen on 20 Mar 2014
Answered: David Nguyen on 20 Mar 2014
Dear All,
I am currently working on a GUI using Matlab GUIDE.
I work with the handles to store some data to be available for all callbacks.
But here comes my problem.
When I introduce additionnal functions into the different callbacks and if those functions try to add specific data to the handles, I have a feeling that the handles is saved only after the callback terminates.
Here is my concrete example:
% Button Callback
function button1_Callback(hObject, eventdata, handles)
% Call specific function
myFunction(handles);
% Use specific data
myOperation = handles.myData + 1;
% Specific function
function myFunction(handles)
% Store data in handles
handles.myData = 1;
% Save handles
guidata(gcbo, handles);
If I proceed this way, I obtain the following error:
Reference to non-existent field 'myData'.
I partially solved the problem by waiting the callback to be closed. And then myData is indeed available for further processing.
My question is therefore the following:
Am I doing the data storage and save right? Is there a way to make myData available already inside the callback (as it is done in my example)?
I hope I was clear in the definition of my problem, in any case I can provide further information upon request.
Thank you very much for your help and have a nice day.
David N.

Accepted Answer

David Nguyen
David Nguyen on 20 Mar 2014
Here is a possible solution:
% Button Callback
function button1_Callback(hObject, eventdata, handles)
% Call specific function
handles = myFunction(handles);
% Use specific data
myOperation = handles.myData + 1;
% Specific function
function [newHandles] = myFunction(handles)
% Store data in handles
handles.myData = 1;
% Save handles
newHandles = handles;
Maybe gcbf could give also some results. I let you try^^

More Answers (3)

nl2605
nl2605 on 20 Mar 2014
Edited: nl2605 on 20 Mar 2014
You are doing it alright. The problem is when you store your handles structure. You use gcbo. So it stores only for that callback. Instead store it in hObject or whatever your handles structure is. In your myFunction write guidata(hObject,handles) rather than using gcbo.

David Nguyen
David Nguyen on 20 Mar 2014
Dear nl2605,
I changed my code to:
% Button Callback
function button1_Callback(hObject, eventdata, handles)
% Call specific function
myFunction(hObject, handles);
% Use specific data
myOperation = handles.myData + 1;
% Specific function
function myFunction(hObject, handles)
% Store data in handles
handles.myData = 1;
% Save handles
guidata(hObject, handles);
But the problem remains the same. Maybe I misunderstand something.
Thanks for your answer and take care.
David N.
  1 Comment
nl2605
nl2605 on 20 Mar 2014
Its still giving the same error? That's strange. Its working fine for me.

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David Nguyen
David Nguyen on 20 Mar 2014
Dear nl2605,
I am really surprised that you get the code running.
I checked twice and I still have the same error:
Reference to non-existent field 'myData'.
Unless I wait for the callback to finish.
Do you have any idea where it might comes from?
Thanks and regards.
David N.
  2 Comments
David Nguyen
David Nguyen on 20 Mar 2014
This is what I did also to solve the problem. I also feel that it is not optimal but... at least it works^^
Many thanks again nl2605. I will write a formal solution for other readers.
Cya
David N.

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