Function error in app designer : too many output arguments

Hello,

I'm in trouble with a function I've coded this afternoon. It works perfectly on a classic matlab script, but when I try to use this function in the App Designer I get errors. In the code bellow, the function is "useless" but it should be operational. The purpose of this program is to fill in a tree node component from the first 3 columns of a table. The filling part is not visible because it is incomplete and anyway the program stops before.

1. This is the function I've created (this function is ok, the problem come from when I'm calling it)

    properties (Access = private)
        arraySousElementUnique
    end
    
    methods (Access = private)
        
        %%Purpose: this function allows to fill the tree selector by finding the values associated with a value in a table.
        function sousElementUnique(app, tableau, colonneSource, valeurSource, colonneDestination)            
            
            j=1;
            %Scrolls through the table, if an item matches the source value, then the function stores the associated value in an array. 
            for i=1:height(tableau)
                if (cell2mat(tableau{i, colonneSource}) == valeurSource) && (convertCharsToStrings(cell2mat(tableau{i,colonneDestination})) ~= "")
                    app.arraySousElementUnique(j) = convertCharsToStrings(cell2mat(tableau{i,colonneDestination}));
                    j = j + 1;
                end
            end
            %makes values unique
            app.arraySousElementUnique = unique(app.arraySousElementUnique);
        end
    end

2. This is the startup function where I try to call the function I coded

    function startupFcn(app)
            
            app.arraySousElementUnique = strings;
            
              
            tableauEvenManVoi = readtable('variable_evenement.xlsx');
            %%can be replace by
            %even = {'Paris';'Madrid';'Madrid';'Paris';'Madrid'};
            %manche = {'Q1';'Q1';'Q1';'Q2';'Q3'};
            %voiture = {'51';'51';'49';'43';'23'};
            %tableauEvenManVoi = table(even,manche,voiture)
                     
            evenement = unique(tableauEvenManVoi{:,1});
            
            for i= 1:length(evenement)
                %%fill node
                manche = sousElementUnique(app,tableauEvenManVoi,1,convertCharsToStrings(evenement{i}),2)
                for j= 1:length(manche)
                    %%fill node
                    voiture = app.sousElementUnique(tableauEvenManVoi, 2, convertCharsToStrings(manche{j}), 3);
                    for k = 1:length(voiture)
                        %%fillnode
                    end
                end
            end

        end

3. The error message

Error using appMatlabTest/sousElementUnique
Too many output arguments.

Error in appMatlabTest/startupFcn (line 48)
                manche = sousElementUnique(app,tableauEvenManVoi,1,convertCharsToStrings(evenement{i}),2)
 
Error using matlab.apps.internal.GraphicsCallbackProxy/runCallbackFunction (line 23)
Error while evaluating GraphicsCallbackProxy CallbackFcn.

Answer 1

[Steven Lord]

The error message is correct. The private method is defined to return 0 output arguments.

function sousElementUnique(app, tableau, colonneSource, valeurSource, colonneDestination) 

You are calling it and asking it to return 1 output argument.

manche = sousElementUnique(app,tableauEvenManVoi,1,convertCharsToStrings(evenement{i}),2)

You're calling the function with too many output arguments since 1 is greater than 0. Either change the definition of sousElementUnique so it returns an output argument or change the locations where you call it so those locations call sousElementUnique with 0 output arguments.

[Robin Scarpellini]

Oh all right. I admit I struggled with a series of error messages and I lost track a bit. Thank you very much.