Command for DatePicker in WPF project

Question

I'm working on a WPF project using MVVM and I want to create a command for a DatePicker but I have no luck. I have this setup but it doesn't trigger the command on Date selection. What I want to do is when the user selects a date in the DatePicker, it'll trigger the command and call the function updateData() (in the DateSelectedCommand.cs). I can see that the command is triggered but updateData() is not called. I guess this line of code parameter is DateTime selected_date is wrong which causes the function not being executed. I'm not sure how I can get the selected date and pass in updateData() as its argument.

Home.xaml

<DatePicker SelectedDate="{Binding SelectedDate}" >
      <i:Interaction.Triggers>
            <i:EventTrigger EventName="SelectedDateChanged">
                    <i:InvokeCommandAction Command="{Binding DateSelectedCommand}"/>
            </i:EventTrigger>
       </i:Interaction.Triggers>
</DatePicker>

HomeVM.cs

private DateTime _selectedDate;
public DateTime SelectedDate
{
   get { return _selectedDate; }
   set { _selectedDate = value; OnPropertyChanged(); }
}

public DateSelectedCommand DateSelectedCommand { get; set; }  

//CONSTRUCTOR  
public HomeVM(){
    SelectedDate = DateTime.Today;
    DateSelectedCommand = new DateSelectedCommand(this);
}

DateSelectedCommand.cs

using Dental_Practice_Monitor.Utilities;
using Dental_Practice_Monitor.ViewModel;
using System;
using System.Threading.Tasks;
using System.Windows.Input;

namespace Dental_Practice_Monitor.Commands
{
    public class DateSelectedCommand : ICommand
    {
        public HomeVM VM { get; set; }
        public event EventHandler CanExecuteChanged;

        public DateSelectedCommand(HomeVM vm)
        {
            VM = vm;
        }

        public bool CanExecute(object parameter)
        {
            return true;
        }

        public async void Execute(object parameter)
        {
            if(parameter is DateTime selected_date)
            {
                VM.updateData(selected_date); 
               // (this is the function I want to call when user selects a date but it doesn't seem to work)
            }
        }
    }
}

Updated 5/2/2023: I figured I could just use the SelectedDate property in HomeVM.cs instead of using the object parameter in DateSelectedCommand.cs.

Answer 1

It sounds like u have not initialized the DateSelectedCommand in your HomeVM-Constructor.

public class HomeVM()
{
   //some other code here
   DateSelectedCommand = new DateSelectedCommand(this);
}