如何从ViewModel WPF MVVM禁用DatePicker

Question

I am developing a WPF application using WPF, I have a combobox which selected item is bound to viewmodel and i have a datepicker. I want to Disable the datepicker in the view depending on the selecteditem of the combobox.

the combo:

<ComboBox x:Name="comboBox2" Grid.Row="6" Grid.Column="1" SelectedIndex="0" ItemsSource="{Binding Path=DueDateOptions}" SelectedValue="{Binding Urgent}">

the datepicker:

<DatePicker x:Name="datePicker1" Grid.Row="6" Grid.Column="2" SelectedDate="{Binding DueDate, Mode=TwoWay}"/>

how can I achieve this purpose, I hope for a little help.

Answer 1

One way to achieve this is, adding a property to the ViewModel and binding IsEnabled property of the DatePicker to that. Then you need to set the property inside the setter of Urgent property: (assuming that you have a property named Urgent in your ViewModel):

class YourViewModel {
    private bool allowPickDate;
    public bool AllowPickDate {
        get {
            return this.allowPickDate;
        }
        set {
            if (this.allowPickDate != value) {
                this.allowPickDate = value;
                this.OnPropertyChanged("AllowPickDate");
            }
       }
   }
   public UrgentType Urgent {
       get {
           ....
       }
       set {
           ....
           if (value == [whatever you expect]) {
               this.AllowPickDate = true;
           }
           else {
               this.AllowPickDate = false;
           }
       }
  }

XAML:

  <DatePicker x:Name="datePicker1" IsEnabled={Binding AllowPickDate} Grid.Row="6" Grid.Column="2" SelectedDate="{Binding DueDate, Mode=TwoWay}"/>

Answer 2

You can create property IsDatePickerEnabled in your viewmodel and bind property IsEnabled on datepicker to this property.

<DatePicker x:Name="datePicker1" Grid.Row="6" Grid.Column="2" SelectedDate="{Binding DueDate, Mode=TwoWay}" IsEnabled="{Binding IsDatePickerEnabled}"/>    

private bool _isDatePickerEnabled;
public bool IsDatePickerEnabled
{
    get{return _isDatePickerEnabled;}
    set 
    {
        _isDatePickerEnabled = value;
        OnPropertyChanged(()=>IsDatePickerEnabled);
    }
}

Then in the setter of Urgent property call method which will determine whether the data picker is enabled or not.

private void Foo()
{
...
IsDataPickerEnabled = true/false;
}