DateTimePicker + WPF + binding + accept dd/MM/yyyy via userinput

Question

Simplified Question:

I have a datepicker in WPF. I enter a value 30/10/1983 in the textbox of the datepicker. I need the value to be posted back to my viewmodel, where in I have bound it to a DateTime? property.

Is there any way I can achieve this. mm/dd/yyyy format triggers a postback but not dd/mm/yyyy.

The DatePicker code is as below.

<DatePicker Grid.Row="2" Name="inputDate"
                Text="{Binding BirthDate,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
                >

</DatePicker>

The view model property is as below.

private DateTime? birthDate;

    public DateTime? BirthDate
    {
        get
        {
            return this.birthDate;
        }
        set
        {
            this.birthDate = value;
            OnPropertyChanged("BirthDate");
        }
    }

I enter a value 10/10 into the datepicker textbox, the setter gets called with a value, but the moment I enter an entire date 30/10/1983, I still have the view model property which is equal to NULL.

I have changed the Format to English-UnitedKingdom, in the calendar settings, and my CurrentCulture reflects en-GB appropriately.

Original Question:

I have a datetimepicker control in WPF, which I have bound the text property to a Nullable DateTime in the view model.

The problem I am facing is when I enter a value in the format MM/dd/yyyy, I do get a value postback in the view model, indicating the new value.

But when I enter the value in dd/MM/yyyy format, I do not get a notification in the view model and the value is lost. The bound propertyin the view model is null.

The short date format is the one which I have specified in the calendar settings & dateFormat, within which for a short date format I provide the entry as "dd/MM/yyyy".

Could someone please help me with this scenario where in I accept date in dd/MM/yyyy format, and I do not want to hardcode, I wish to pick up the short date format from the calendar settings and also, I wish to recieve the updated value in the view model too.

Answer 1

The problem is related that a not valid date will not set with a correct value your ViewModel DateTime property. So, you can intercept it and convert correctly with a CONVERTER.

An example:

public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        string strValue = System.Convert.ToString(value);
        DateTime resultDateTime;
        if (DateTime.TryParse(strValue, out resultDateTime))
        {
            return resultDateTime;
        }
        return value;    
    }

And your XAML code will be like:

 <DatePicker 
     Text="{Binding BirthDate,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
     SelectedDate="{Binding RelativeSource={RelativeSource Self},Path=Text,
     Converter={StaticResource DateConverter}}"
  />