How to properly format DateTime with annotations in WPF MVVM application

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How to properly format DateTime with annotations in WPF MVVM application

Francesco Paolo La Gamba 21

Hi Community,

I have a seemingly trivial problem: I'm trying Community.MVVM.Toolkit and I've created a class that exposes some properties among which there is a DateTime type (BirthDate).

Well, despite several searches on the web, I can not get the formatting of the date in the my required format using the Annotations.

The format I would like to obtain is of type "yyyy-MM-dd" without the time.

I specified it in the property annotations using the following annotation:

      [ObservableProperty]
      [NotifyDataErrorInfo]
      [Required]
      [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
      public DateTime?  _birthDate;

The XAML definition:

<TextBox x:Name="txtBirthDate" Width ="200"   Text="{Binding Path=BirthDate,  UpdateSourceTrigger=LostFocus,      ValidatesOnDataErrors=true}"  Margin="5" />

Now if I enter the date 30/11/2022 ( November 30, 2022 in italian format)

the result in the TextBox is "11/30/2022 12:00:00 AM"

The specified format is absolutely not taken into consideration.

How can I solve the problem ?

Maybe I could add a further property that transforms the date into a string... but in this way I lose the advantages of the toolkit and I don't want to do it, if possible.

Best regards

Francesco Paolo La Gamba

Hui Liu-MSFT 48,676 Microsoft External Staff

Hi,@Francesco Paolo La Gamba. Welcome Microsoft Q&A. Have you set CultureInfo? I ran into an error using the following code test.

 public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            DataContext = new MyData();
            CultureInfo.DefaultThreadCurrentCulture = new CultureInfo("it-CH");
           CultureInfo.DefaultThreadCurrentUICulture = new CultureInfo("it-CH");
        }
     
    }
   
    public partial class MyData : ObservableValidator
    {
        [ObservableProperty]
        [NotifyDataErrorInfo]
        [Required]
        [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
        //[DisplayFormat(DataFormatString = "{0:d}", ApplyFormatInEditMode = true)]
      

        public DateTime? _birthDate;
    }

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Hui Liu-MSFT 48,676 Reputation points Microsoft External Staff

2023-07-04T08:25:04.2633333+00:00

Hi,@Francesco Paolo La Gamba. Welcome Microsoft Q&A. Have you set CultureInfo? I ran into an error using the following code test.

public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); DataContext = new MyData(); CultureInfo.DefaultThreadCurrentCulture = new CultureInfo("it-CH"); CultureInfo.DefaultThreadCurrentUICulture = new CultureInfo("it-CH"); } } public partial class MyData : ObservableValidator { [ObservableProperty] [NotifyDataErrorInfo] [Required] [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)] //[DisplayFormat(DataFormatString = "{0:d}", ApplyFormatInEditMode = true)] public DateTime? _birthDate; }

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