# Validation

The DataGrid allows you to validate the data and display hints if the validation is not passed. To benefit from this feature, the objects populating the `ItemsSource` of the component need to implement the `INotifyDataErrorInfo` interface.

## ValidateViewModelBase

You can use the `ValidateViewModelBase` class, which provides an implementation of `INotifyDataErrorInfo` to quickly set up your objects. The following examples demonstrate how to populate the DataGrid with objects that include some custom validation logic.

#### **Define the DataGrid in XAML**

```XAML
<Grid xmlns:telerikGrid="using:Telerik.UI.Xaml.Controls.Grid">
	<Grid.DataContext>
		<local:ViewModel />
	</Grid.DataContext>
	<telerikGrid:RadDataGrid ItemsSource="{Binding Items}" AutoGenerateColumns="False" UserEditMode="Inline" >
		<telerikGrid:RadDataGrid.Columns>
			<telerikGrid:DataGridDateColumn PropertyName="Date" CellContentFormat="{}{0:d}"/>
		</telerikGrid:RadDataGrid.Columns>
	</telerikGrid:RadDataGrid>
</Grid>
```

#### **Define the Model and ViewModel**

```C#
public class ViewModel
{
	public ViewModel()
	{
		this.Items = this.GetData();
	}

	public ObservableCollection<Data> Items { get; set; }

	private ObservableCollection<Data> GetData()
	{
		var data = new ObservableCollection<Data>();
		for (var i = 0; i < 10; i++)
		{
			data.Add(new Data { Date = DateTime.Today.AddDays(-i) });
		}

		return data;
	}
}
public class Data : ValidateViewModelBase
{
	private readonly DateTimeOffset maxDate = DateTime.Today.AddDays(10);

	private DateTimeOffset date;

	public DateTimeOffset Date
	{
		get
		{
			return this.date;
		}
		set
		{
			this.date = value;

			if (this.date > this.maxDate)
			{
				this.AddError("Date", string.Format("Date cannot be set after {0:d}.", this.maxDate));
			}
			else
			{
				this.RemoveErrors("Date");
			}

			this.OnPropertyChanged();
		}
	}
}
```

**Result from the Examples**

![WinUI DataGrid Validation](https://www.telerik.com/winui/documentation/assets/a6ad0c8bfc5efdf08b99263d161e360a/datagrid-validation.png)

## See Also

* [Editing](https://www.telerik.com/winui/documentation/controls/raddatagrid/editing/datagrid-overview)