How to access the error line number where an error occurred with try/catch MException? App Designer

Hi,

I've developed an App Designer App and incorporated try-catch statements to enhance stability. Now, I aim to display information about where an error occurred. To achieve this, I have the following structure:

            ErrorInfo = 'DeleteDataButtonPushed';
            try
                %Code to be executed 
                    
            catch ME
                DisplayErrorMsg(app, ErrorInfo, ME);
            end
            
            
            function DisplayErrorMsg(app, ErrorInfo, ME)
                MsgError = ME.message;
                MsgId = ME.identifier;
                
                MsgLine = ME.stack.line; % ME.stack.line contains sometimes more than one line
                
                Msg = ['Error in Line ' MsgLine newline MsgError newline MsgId newline ErrorInfo newline app.ErrorMsg];
                uiwait(msgbox(Msg,"Error","error"));      
            end
          

My Problem is: ME.stack.line contains sometimes more than one line:

ME.stack.line

ans =

263

ans =

4275

ans =

62

How to access the imformation in the second row/ans?

Things that I tried:

ME.stack

ans =

3×1 struct array with fields:

file

name

line

size(ME.stack.line)

ans =

1 1

ME.stack.line(2) -- Intermediate dot '.' indexing produced a comma-separated list with 3 values, but it must produce a single value when followed by subsequent indexing operations.

ME.stack.line{2}-- Intermediate dot '.' indexing produced a comma-separated list with 3 values, but it must produce a single value when followed by subsequent indexing operations.

Msg = getReport(ME); finds all the lines, but the text it generates is huge and not very practical.

Thanks for your support!

Answer 1

[Jaimin]

Hello @Marcel Rapp

To display all error messages using the “msgbox” function, iterate through all error lines from “ME.stack” array.

I have attached a sample code for better understanding.

function DisplayErrorMsg(app,ErrorInfo, ME)
            MsgError = ME.message;
            MsgId = ME.identifier;
            
            % Initialize an empty string to store line information
            MsgLines = '';
            
            % Iterate over each element in the ME.stack array
            for i = 1:length(ME.stack)
                % Append each line number to the MsgLines string
                MsgLines = [MsgLines, num2str(ME.stack(i).line), ' '];
            end
            
            % Construct the full error message
            Msg = ['Error in Lines: ' MsgLines newline ...
                   'Error Message: ' MsgError newline ...
                   'Error ID: ' MsgId newline ...
                   'Error Info: ' ErrorInfo];
            
            % Display the error message in a message box
            uiwait(msgbox(Msg, "Error", "error"));
end

I hope this will be helpful.