Undefined function error when passing data in multiwindow apps

Hello,

I'm trying to create a multiwindow app. The way I've got it setup, is the user will make some selections on the main app, click a button, and if a certain condition is met based on their selections, a second app window will open where they will make some additional inputs. Once complete, they will click a button which will send their inputs back to the main app and resume its execution (in order to create a graph in Excel, in my case). I've followed the instructions in the MathWorks documentation for this (Create Multiwindow Apps in App Designer - MATLAB & Simulink (mathworks.com)), but I am getting an error which says "Undefined function 'addVariableUnit' for input arguments of type 'double'.", where 'addVariableUnit' is the public function in my main app, which I am calling from the second app, in order to pass over the users inputs. It seems that the second app does not recognize this function, even though I've made it public in the main app. Below is my code. I've attached the mlapp files as well, where the lines of interest in the main app are 100-106 (calling the second app), 162-174 (public function in the main app to retrieve second apps data). The second app is quite short.

Main app (createChart_App.mlapp):

methods (Access = private)
        
        function [yTitle1] = createChartErrorChecks (app, wb_proc, A, axis)

            ...
        
            %checking condition based on users selections
            if yUnit == "none"
                
                %Open second app window
                app1 = enterVariableUnit;
                
                %pause execution until window is closed
                while isvalid(app1); pause(1); end
                
            end
            
        end
end
            
methods (Access = public)
        %public function to pass data from second app to main app
        function addVariableUnit(app, variable, unit)
            
            %do stuff with variable and unit            
            ...
                
        end
end

Second app (enterVariableUnit.mlapp):

    properties (Access = private)
        CallingApp % Main app object
        end    
        
    methods (Access = private)

        % Button pushed function: EnterButton
        function EnterButtonPushed(app, event)

            %call main apps public function, provide it with the users inputs
            addVariableUnit(app.CallingApp, app.variableUnit.Value, app.variableName.Value);

            delete(app)
            
        end
        end
        

Answer 1

[Reshma Nerella]

Hi,

In the function "createChartErrorChecks" in the main app, you need to open the dialog app by passing the main app as the argument.

Instead of

app1 = enterVariableUnit;

Use the following line of code: Create a private property "DialogApp" and pass the main app as argument.

app.DialogApp = enterVariableUnit(app);

For more information, refer to the following documentation page: Create Multiwindow Apps in App Designer

[Patrick Mirek]

Yes I was missing that, thank you! In addition, I needed to create a startup function in my dialog app to recieve this "app" argument:

% Code that executes after component creation

function startupFcn(app, mainapp)

%take the mainapp variable (from createChart_App) and assign it

%to CallingApp

app.CallingApp = mainapp;

end

I missed these originally because in the Matlab documentation, they were under the heading "Send Information to the Dialog Box", and I was only receiving information from the dialog box, not sending to it, so I thought I didn't need that.