Import doesn't works when I use them in the 'startupFcn()' of APP designer

I have imported matlab.http.* and other HTTP packages in the startupFcn, but when other method (function) are called, it still prompts error messages showing that I didn't import them ... I have to import them in EVERY methods that will use those packages... BUT I think this approach sucks ... Anyone who can give me a simpler and reasonable way to solve this? My code is attached below...

startupFcn()

    methods (Access = private)

        % Code that executes after component creation
        function startupFcn(app)
            import matlab.net.*
            import matlab.net.http.*
            import matlab.net.http.io.*

            disp("1. Matlab.net tools loaded ...")

            api_key = string(fileread("KEY.txt"));
            if api_key ~= ""
                disp(["2. API key loaded: "+ api_key]);
            else
                disp("Please Provide your API KEY by editing 'KEY.txt'.");
            end
            
            % Setup hyper parameters when startup
            app.attempt_counter = 0;
            app.max_attempt = 2;
            app.max_tokens = 1024;
            app.n_solution = 1;
            app.prompt = "";

            % Setup HTTP request header
            app.header = [
                HeaderField('Content-Type', 'application/json')
                HeaderField('Authorization', ['Bearer ' + api_key])
            ]';

            disp("3. Header generated: ");
            disp(app.header(2).Value);
        end

Other function that will use HTTP (I have to import them again)

        % Value changed function: ModelDropDown
        function ModelDropDownValueChanged(app, event)
            import matlab.net.*
            import matlab.net.http.*
            import matlab.net.http.io.*

            selected_model = app.ModelDropDown.Value;

            if selected_model == "GPT3.5Turbo"
                app.model = 'gpt-3.5-turbo';
                app.endpoint = "https://api.openai.com/v1/chat/completions";
                disp(app.endpoint);
            elseif selected_model == "GPT3.5"
                app.model = 'gpt-3.5-0301';
            else
                app.model = 'davinci-v3';
            end

            disp("Selected Model is: " + app.model);
        end

Answer 1

[Kanishk]

Hi Dyson,

I understand you want to import packages in every method by importing them once.

In MATLAB, the import statement is scoped to the function or script in which it is called. This means that if you use import within a function, it won't be available in other functions unless you import it again in each of those functions. MATLAB does not have a global import feature like some other programming languages. You can read more about it in the following MATLAB answer.

https://www.mathworks.com/matlabcentral/answers/1619190-how-to-declear-global-import-java-awt-robot-and-import-java-awt-event#answer_864985

However, you can take one of following approaches to simplify the usage of packages across different methods in the app:

• Usage of fully qualified names instead of using import statements in every method.

response = matlab.net.http.RequestMessage; 

• Declaration of helper functions which encapsulates the functionality of the package. You need to import the package once and use the helper function.

methods (Access = private) 
    function response = baseHttpFunction(app, uri) 
        import matlab.net.http.* 
        request = RequestMessage(); 
        response = request.send(uri); 
    end 
    
    function response = anotherFunction(app, uri) 
        response = app.baseHttpFunction(uri); 
    end 
end 

To learn about importing packages, please go through this official MATLAB documentation.

https://www.mathworks.com/help/releases/R2022b/matlab/ref/import.html

Hope this helps!

Thanks