adding a new method to ICommand (C# WPF)

Question

here is my helper class to use in different ViewModelClasses in my project;

public class MOpenFileDialog : ViewModelBase
    {
        #region Properties

        private OpenFileDialog _openDialog;
        public OpenFileDialog Dialog
        {
            get { return _openDialog; }
            set 
            { 
                _openDialog = value;
                RaisePropertyChanged(nameof(Dialog));
            }
        }

        // some other properties

        #endregion

        #region Constructors

        public MOpenFileDialog()
        {            
            OpenFileCommand = new RelayCommand<object>(OpenFile);

            Dialog = new OpenFileDialog()
            {
                FileName = "Documen",
                Filter = "All Files|*.*",
            };
        }


        #endregion

        #region Methods

        public void OpenFile(object param)
        {
           // somecode
        }

        // some other methods

        #endregion

        #region Commands
        public ICommand OpenFileCommand { get; set; }

        #endregion


    }

and here in myClassVM i have an instant of MOpenFileDialog and i'm trying to add a new method to OpenFileCommand;

public class myClassVM : ViewModelBase
    {
        #region Properties

        public MOpenFileDialog Opendial { get; set; }

        #endregion

        #region Constructor

        public CollectNamesVM()
        {
            Opendial = new MOpenFileDialog() { };
            Opendial.Dialog.Multiselect = true;
            //Opendial.OpenFileCommand += CollectFilesFolder; // Wrong Way

        }

        #endregion

        #region Methods

        public void CollectFilesFolder()
        {
            // toDo
        }

       }

i want to add another method to be implemented when openFileCommand fired, i did a wrong trial just to explain what i want to do.

any help will be appreciated.

Answer 1

Use delegate in 5 step below:

Step 1. Create a delegate. Example you want to pass an string[] (string array, data type of FileNames with your code: Opendial.Dialog.Multiselect = true)

Step 2. Create a event using the delegate in step 1

Step 3. Raise the event created in step 2 everywhen you want in MOpenFileDialog

Step 4. I cant know what do you want here, but Its same as this

Step 5. CollectFilesFolder method 's params are same as the delegate 's params

    // 1. Create a delegate. Example you want to pass an string array
    public delegate void OpenFileCommand(string[] fileNames);
    public class MOpenFileDialog : ViewModelBase
    {
        // 2. Create a event using the delegate in step 1
        public event OpenFileCommand OnOpenFileCommand;

        // 3. Raise the event created in step 2 everywhen you want
        public void SomeMethod(string[] fileNames)
        {
            this.OnOpenFileCommand.Invoke(fileNames);
        }

        #region Properties

        private OpenFileDialog _openDialog;
        public OpenFileDialog Dialog
        {
            get { return _openDialog; }
            set 
            { 
                _openDialog = value;
                RaisePropertyChanged(nameof(Dialog));
            }
        }

        // some other properties

        #endregion

        #region Constructors

        public MOpenFileDialog()
        {            
            OpenFileCommand = new RelayCommand<object>(OpenFile);

            Dialog = new OpenFileDialog()
            {
                FileName = "Documen",
                Filter = "All Files|*.*",
            };
        }


        #endregion

        #region Methods

        public void OpenFile(object param)
        {
           // somecode
        }

        // some other methods

        #endregion

        #region Commands
        public ICommand OpenFileCommand { get; set; }

        #endregion
    }

    public class myClassVM : ViewModelBase
    {
        #region Properties

        public MOpenFileDialog Opendial { get; set; }

        #endregion

        #region Constructor

        public CollectNamesVM()
        {
            Opendial = new MOpenFileDialog() { };
            Opendial.Dialog.Multiselect = true;
            // 4. I cant know what do you want here, but Its same as this
            Opendial.OnOpenFileCommand += CollectFilesFolder(Opendial.Dialog.FileNames); // Wrong Way

        }

        #endregion

        #region Methods
        // 5. CollectFilesFolder has params same as the delegate
        public void CollectFilesFolder(string[] fileNames)
        {
            // toDo
        }
    }