XAML MVVM DatePicker - How do I get the data?

0
votes

I've got a View with a DatePicker bound to a DateTime property in my ViewModel. However, the date value always appears as null, even when I select a different value than the default. Anyone have success with the DatePicker? If so, what am I getting wrong?

Relevant Code:

View:

<DatePicker x:Name="startDateUpdatePick" HorizontalAlignment="Left" Height="23" VerticalAlignment="Top" Width="120" Margin="1.5" 
   Text="{Binding SelectedProjectData.ProjectStartDate, UpdateSourceTrigger=PropertyChanged, TargetNullValue=''}"/>

ViewModel: 

public PSViewModel()
    {
        SelectedProjectData = new Project();
    }

Model:

public class Project : INotifyPropertyChanged
{
    private DateTime _projectStartDate;

    public DateTime ProjectStartDate
    {
        get { return _projectStartDate; }
        set
        {
            _projectStartDate = value;
            RaisePropertyChanged();
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    private void RaisePropertyChanged([CallerMemberName] string caller = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(caller));
    }
}

Edit: the XAML is bound to a non-nullable DateTime, but I have other datepickers in the same setup that are bound to nullable DateTime and they don't work either.

2
c#xamlmvvmdatepicker
What's the DataContext of the DatePicker? And your ViewModel won't even compile, so who knows what's actually going on in there. Project looks correct. - user1228
Also, grab you a copy of Snoop. You can investigate binding errors easily at runtime. - user1228
is SelectedProjectData a public property? Is your view's DataContext set to an instance of PSViewModel? - plast1k

2 Answers

4
votes

The property is SelectedDate, not Text.

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Read... the... documentation...

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0
votes

View:

<StackPanel Orientation="Horizontal">
    <DatePicker SelectedDate="{Binding SelectedDate, 
        UpdateSourceTrigger=PropertyChanged}"
        DisplayDateStart="{Binding StartDate}" DisplayDateEnd="{Binding EndDate}"/>
    <Label Content="{Binding SelectedDate}"/>
</StackPanel>

ViewModel

   public class MainWindowViewModel : INotifyPropertyChanged
    {
        private string _selectedDate;
        public string SelectedDate
        {
            get
            {
                return _selectedDate;
            }
            set
            {
                _selectedDate = value;
                RaisePropertyChanged();
            }
        }

        public DateTime StartDate { get; set; }
        public DateTime EndDate { get; set; }

        public MainWindowViewModel()
        {
            StartDate = new DateTime(2020, 1, 1);
            EndDate = new DateTime(2020, 3, 31);
        }

        public event PropertyChangedEventHandler PropertyChanged;
        public void RaisePropertyChanged([CallerMemberName] string property = "")
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(property));
        }
    }
}