button dosent bind with SelectedDate, to ble to be able

Question

I have created a custom control

public partial class DateTimeZonePicker : ContentView {
    public DateTimeZonePicker() {
        InitializeComponent();
    }
    public static readonly BindableProperty ButtonTextProperty = BindableProperty.Create(
        nameof(ButtonText), typeof(string), typeof(DateTimeZonePicker));
    public string ButtonText {
        get => (string)GetValue(ButtonTextProperty);
        set => SetValue(ButtonTextProperty, value);
    }
    public static readonly BindableProperty IsButtonEnabledProperty = BindableProperty.Create(
        nameof(IsButtonEnabled), typeof(bool), typeof(DateTimeZonePicker));
    public bool IsButtonEnabled {
        get => (bool)GetValue(IsButtonEnabledProperty);
        set => SetValue(IsButtonEnabledProperty, value);
    }
    public static readonly BindableProperty SelectedDateProperty = BindableProperty.Create(
        nameof(SelectedDate), typeof(DateTime), typeof(DateTimeZonePicker));
    public DateTime SelectedDate {
        get => (DateTime)GetValue(SelectedDateProperty);
        set => SetValue(SelectedDateProperty, value);
    }
    public static readonly BindableProperty TimezonesProperty = BindableProperty.Create(
        nameof(Timezones), typeof(List), typeof(DateTimeZonePicker));
    public List Timezones {
        get => (List)GetValue(TimezonesProperty);
        set => SetValue(TimezonesProperty, value);
    }
    public static readonly BindableProperty SelectedTimeZoneProperty = BindableProperty.Create(
        nameof(SelectedTimeZone), typeof(string), typeof(DateTimeZonePicker));
    public string SelectedTimeZone {
        get => (string)GetValue(SelectedTimeZoneProperty);
        set => SetValue(SelectedTimeZoneProperty, value);
    }
    public static readonly BindableProperty IsDateTimePickerVisibleProperty = BindableProperty.Create(
        nameof(IsDateTimePickerVisible), typeof(bool), typeof(DateTimeZonePicker));
    public bool IsDateTimePickerVisible {
        get => (bool)GetValue(IsDateTimePickerVisibleProperty);
        set => SetValue(IsDateTimePickerVisibleProperty, value);
    }
    public static readonly BindableProperty OpenDateTimeProperty = BindableProperty.Create(
        nameof(OpenDateTime), typeof(RelayCommand), typeof(DateTimeZonePicker));
    public RelayCommand OpenDateTime {
        get => (RelayCommand)GetValue(OpenDateTimeProperty);
        set => SetValue(OpenDateTimeProperty, value);
    }
    public static readonly BindableProperty OkButtonClickedCommandProperty = BindableProperty.Create(
        nameof(OkButtonClickedCommand), typeof(RelayCommand), typeof(DateTimeZonePicker));
    public RelayCommand OkButtonClickedCommand {
        get => (RelayCommand)GetValue(OkButtonClickedCommandProperty);
        set => SetValue(OkButtonClickedCommandProperty, value);
    }
    public static readonly BindableProperty CancelButtonClickedCommandProperty = BindableProperty.Create(
        nameof(CancelButtonClickedCommand), typeof(RelayCommand), typeof(DateTimeZonePicker));
    public RelayCommand CancelButtonClickedCommand {
        get => (RelayCommand)GetValue(CancelButtonClickedCommandProperty);
        set => SetValue(CancelButtonClickedCommandProperty, value);
    }
}

But for some reason doesn't want to bind

    [ObservableProperty]
    bool isPickerVisible;
    [ObservableProperty]
    [NotifyPropertyChangedFor(nameof(ButtonText), nameof(IsButtonEnabled))]
    DateTime? selectedDateTime = null;
    [ObservableProperty]
    [NotifyPropertyChangedFor(nameof(IsButtonEnabled))]
    String selectedTimeZone;
    public List Timezones { get; set; }
    public string ButtonText => SelectedDateTime.HasValue ? $"Schedule for {SelectedDateTime:MMMM dd yyyy 'at' HH:mm}" : "";
    public bool IsButtonEnabled => SelectedDateTime.HasValue && !string.IsNullOrEmpty(SelectedTimeZone);
    public MainViewModel() {
        GetTimeZones();
    }
    private void GetTimeZones() {
        Timezones =
            [
                // US Time Zones
                "America/Adak",
                "America/Anchorage",
                "America/Boise",
                "America/Chicago",
                "America/Denver",
                "America/Detroit",
                // Add more US time zones as needed
                // Other Time Zones
                "America/Caracas",
                "America/Guayaquil",
                "Europe/Madrid",
                "Asia/Riyadh"
                // Add more time zones as needed
            ];
    }
    [RelayCommand]
    void OpenDateTimePicker() {
        IsPickerVisible = true;
    }
    [RelayCommand]
    void OkButtonClicked() {
        IsPickerVisible = false;
    }
    [RelayCommand]
    void CancelButtonClicked() {
        IsPickerVisible = false;
    }
    [RelayCommand]
    void ScheduleButtonClicked() {
        //TODO: Schedule the meeting, taking into account the time zone 
    }
}

every time I select moment and put a breakpoint is null

User's image

the picker is opening and hiding with

 [RelayCommand]
    void OkButtonClicked() {
        IsPickerVisible = false;
    }

Answer

Hello,

What I do not understand is that I have to put two ways in xml, when i already put

TwoWay — data goes both ways between source and target
OneWay — data goes from source to target

From this document:Binding mode - .NET MAUI | Microsoft Learn

When data bindings are used with the Model-View-ViewModel (MVVM) pattern, the viewmodel class is the data-binding source, and the view, which consists of views are data-binding targets.

By default, the binding mode is OneWay, data goes from source to target(ViewModel to View).

If you want each view on the page to be initialized with the value of the corresponding property in the viewmodel, but changes in the view should also affect the viewmodel property, you need to change the binding mode to Two way.

If you set the TwoWay in the contentview's xml, data can go between ContentView's child controls and the contentview background code's BindableProperty.

And you set the TwoWay in the BindableProperty, data can go between the ContentView and the Viewmodels. In the end, if you want data can go between ContentView's child controls and viewmodel, please set both of them.

Best Regards,

Leon Lu

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button dosent bind with SelectedDate, to ble to be able

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