How do I pass an integer through a wpf command?

Question

I have a ListView that displays all the days in a month as buttons and each button contains the day number. When I click one of the buttons I want it to take me to that days view. The buttons commands are bound to the ToDayView command. I dont want to make a bunch of different commands for each day that could possibly be in a month. How can I pass the day number through use of the command?

MonthView

    <ListView ItemsSource="{Binding CurrentMonth.Days}" Grid.Row="1">
        <ListView.ItemTemplate>
            <DataTemplate>
                <Button Content="{Binding DayNumber}"  Grid.Row="1" Height="20" Width="100"
                    Command="{Binding ToDayViewCommand}"/>
            </DataTemplate>
        </ListView.ItemTemplate>
    </ListView>

MonthViewModel

public class MonthViewModel : ViewModelBase
{
    private readonly NavigationStore _navigationStore;

    private Month _currentMonth;

    public Month CurrentMonth
    {
        get { return _currentMonth; }
        set 
        { 
            _currentMonth = value;
            OnPropertyChanged("CurrenMonth");
        }
    }

    public void ToDayView(object thing)
    {
        // use parameter as day number
        int dayNumber = 25;

        // find the Day object with that day number
        for(int i = 0; i < CurrentMonth.Days.Count; i++)
        {
            if(CurrentMonth.Days[i].DayNumber == dayNumber)
            {
                // give it to the view model to be displayed
                _navigationStore.CurrentViewModel = new DayViewModel(CurrentMonth.Days[i], _navigationStore);
            }
        }
    }

    public BasicCommand ToDayViewCommand { get; set; }

    public MonthViewModel(Month currentMonth, NavigationStore navigationStore)
    {
        CurrentMonth = currentMonth;
        _navigationStore = navigationStore;
        ToDayViewCommand = new BasicCommand(ToDayView);

    }
}

BasicCommand

public class BasicCommand : CommandBase
{
    readonly Action<object> _execute;

    public BasicCommand(Action<object> execute)
    {
        _execute = execute;
    }

    public override bool CanExecute(object parameter) => true;

    public override void Execute(object parameter)
    {
        _execute.Invoke(parameter);
    }
}

Answer 1

You can define the command parameter in your XAML code:

<Button Content="{Binding DayNumber}"  Grid.Row="1" Height="20" Width="100"
    Command="{Binding ToDayViewCommand}" CommandParameter="25" />

Note that CommandParameter is a dependency property, hence you can also use a binding:

<Button Content="{Binding DayNumber}"  Grid.Row="1" Height="20" Width="100"
    Command="{Binding ToDayViewCommand}" CommandParameter="{Binding AmountDays}" />

In the method, that is invoked by your command, you have to cast the object to an int. Note that your parameter is a string, if you call it like in my first code snippet, hence you have to use int.Parse :

 public void ToDayView(object thing)
    {
        // use parameter as day number
        int dayNumber = int.Parse(thing.ToString());

        // find the Day object with that day number
        for(int i = 0; i < CurrentMonth.Days.Count; i++)
        {
            if(CurrentMonth.Days[i].DayNumber == dayNumber)
            {
                // give it to the view model to be displayed
                _navigationStore.CurrentViewModel = new DayViewModel(CurrentMonth.Days[i], _navigationStore);
            }
        }
    }