Nullable DatePicker (make Date, MinimumDate & MaximumDate nullable)

src/Compatibility/Core/src/Android/Renderers/DatePickerRenderer.cs

@@ -136,7 +136,11 @@ void IPickerRenderer.OnClick()
 			DatePicker view = Element;
 			((IElementController)view).SetValueFromRenderer(VisualElement.IsFocusedPropertyKey, true);
 
-			ShowPickerDialog(view.Date.Year, view.Date.Month - 1, view.Date.Day);
+			var year = view.Date?.Year ?? DateTime.Today.Year;
+			var month = (view.Date?.Month ?? DateTime.Today.Month) - 1;
+			var day = view.Date?.Day ?? DateTime.Today.Day;
+
+			ShowPickerDialog(year, month, day);
 		}
 
 		void ShowPickerDialog(int year, int month, int day)
@@ -164,19 +168,19 @@ void OnCancelButtonClicked(object sender, EventArgs e)
 			Element.Unfocus();
 		}
 
-		void SetDate(DateTime date)
+		void SetDate(DateTime? date)
 		{
 			if (String.IsNullOrWhiteSpace(Element.Format))
 			{
-				EditText.Text = date.ToShortDateString();
+				EditText.Text = date?.ToShortDateString();
 			}
 			else if (Element.Format.Contains('/', StringComparison.Ordinal))
 			{
-				EditText.Text = date.ToString(Element.Format, CultureInfo.InvariantCulture);
+				EditText.Text = date?.ToString(Element.Format, CultureInfo.InvariantCulture);
 			}
 			else
 			{
-				EditText.Text = date.ToString(Element.Format);
+				EditText.Text = date?.ToString(Element.Format);
 			}
 		}
 
@@ -198,7 +202,16 @@ void UpdateMaximumDate()
 		{
 			if (_dialog != null)
 			{
-				_dialog.DatePicker.MaxDate = (long)Element.MaximumDate.ToUniversalTime().Subtract(DateTime.MinValue.AddYears(1969)).TotalMilliseconds;
+				if (Element.MaximumDate is null)
+				{
+					_dialog.DatePicker.MaxDate = (long)DateTime.MaxValue.ToUniversalTime()
+						.Subtract(DateTime.MinValue.AddYears(1969)).TotalMilliseconds;
+
+					return;
+				}
+
+				_dialog.DatePicker.MaxDate = (long)Element.MaximumDate.Value
+					.ToUniversalTime().Subtract(DateTime.MinValue.AddYears(1969)).TotalMilliseconds;
 			}
 		}
 
@@ -207,7 +220,16 @@ void UpdateMinimumDate()
 		{
 			if (_dialog != null)
 			{
-				_dialog.DatePicker.MinDate = (long)Element.MinimumDate.ToUniversalTime().Subtract(DateTime.MinValue.AddYears(1969)).TotalMilliseconds;
+				if (Element.MinimumDate is null)
+				{
+					_dialog.DatePicker.MinDate = (long)DateTime.MinValue.ToUniversalTime()
+						.Subtract(DateTime.MinValue.AddYears(1969)).TotalMilliseconds;
+
+					return;
+				}
+
+				_dialog.DatePicker.MinDate = (long)Element.MinimumDate.Value
+					.ToUniversalTime().Subtract(DateTime.MinValue.AddYears(1969)).TotalMilliseconds;
 			}
 		}
 

src/Compatibility/Core/src/Windows/DatePickerRenderer.cs

@@ -127,9 +127,9 @@ void OnControlDateChanged(object sender, DatePickerValueChangedEventArgs e)
 			if (Element == null)
 				return;
 
-			if (Element.Date.CompareTo(e.NewDate.Date) != 0)
+			if (Element.Date == null || Element.Date?.CompareTo(e.NewDate.Date) != 0)
 			{
-				var date = e.NewDate.Date.Clamp(Element.MinimumDate, Element.MaximumDate);
+				var date = e.NewDate.Date.Clamp(Element.MinimumDate ?? DateTime.MinValue, Element.MaximumDate ?? DateTime.MaxValue);
 				Element.Date = date;
 
 				// set the control date-time to clamped value, if it exceeded the limits at the time of installation.
@@ -148,10 +148,10 @@ bool CheckDateFormat()
 		}
 
 		[PortHandler]
-		void UpdateDate(DateTime date)
+		void UpdateDate(DateTime? date)
 		{
 			if (Control != null)
-				Control.Date = new DateTimeOffset(new DateTime(date.Ticks, DateTimeKind.Unspecified));
+				Control.Date = new DateTimeOffset(new DateTime(date?.Ticks ?? 0, DateTimeKind.Unspecified));
 
 			UpdateDay();
 			UpdateMonth();
@@ -288,18 +288,18 @@ void UpdateFont()
 		void UpdateMaximumDate()
 		{
 			if (Element != null && Control != null)
-				Control.MaxYear = new DateTimeOffset(new DateTime(Element.MaximumDate.Ticks, DateTimeKind.Unspecified));
+				Control.MaxYear = new DateTimeOffset(new DateTime(Element.MaximumDate?.Ticks ?? DateTime.MaxValue.Ticks, DateTimeKind.Unspecified));
 		}
 
 		[PortHandler]
 		void UpdateMinimumDate()
 		{
-			DateTime mindate = Element.MinimumDate;
+			DateTime mindate = Element.MinimumDate ?? DateTime.MinValue;
 
 			try
 			{
 				if (Element != null && Control != null)
-					Control.MinYear = new DateTimeOffset(new DateTime(Element.MinimumDate.Ticks, DateTimeKind.Unspecified));
+					Control.MinYear = new DateTimeOffset(new DateTime(Element.MinimumDate?.Ticks ?? DateTime.MinValue.Ticks, DateTimeKind.Unspecified));
 			}
 			catch (ArgumentOutOfRangeException)
 			{

src/Compatibility/Core/src/iOS/Renderers/DatePickerRenderer.cs

@@ -176,8 +176,8 @@ void OnStarted(object sender, EventArgs eventArgs)
 		[PortHandler]
 		void UpdateDateFromModel(bool animate)
 		{
-			if (_picker.Date.ToDateTime().Date != Element.Date.Date)
-				_picker.SetDate(Element.Date.ToNSDate(), animate);
+			if (_picker.Date.ToDateTime().Date != Element.Date?.Date)
+				_picker.SetDate(Element.Date?.ToNSDate(), animate);
 
 			// Can't use Element.Format because it won't display the correct format if the region and language are set differently
 			if (string.IsNullOrWhiteSpace(Element.Format) || Element.Format.Equals("d", StringComparison.OrdinalIgnoreCase))
@@ -200,11 +200,11 @@ void UpdateDateFromModel(bool animate)
 			}
 			else if (Element.Format.Contains('/', StringComparison.Ordinal))
 			{
-				Control.Text = Element.Date.ToString(Element.Format, CultureInfo.InvariantCulture);
+				Control.Text = Element.Date?.ToString(Element.Format, CultureInfo.InvariantCulture);
 			}
 			else
 			{
-				Control.Text = Element.Date.ToString(Element.Format);
+				Control.Text = Element.Date?.ToString(Element.Format);
 			}
 		}
 
@@ -237,13 +237,13 @@ void UpdateCharacterSpacing()
 		[PortHandler]
 		void UpdateMaximumDate()
 		{
-			_picker.MaximumDate = Element.MaximumDate.ToNSDate();
+			_picker.MaximumDate = Element.MaximumDate?.ToNSDate();
 		}
 
 		[PortHandler]
 		void UpdateMinimumDate()
 		{
-			_picker.MinimumDate = Element.MinimumDate.ToNSDate();
+			_picker.MinimumDate = Element.MinimumDate?.ToNSDate();
 		}
 
 		[PortHandler]

src/Controls/samples/Controls.Sample/Pages/Controls/DatePickerPage.xaml

@@ -89,6 +89,14 @@
                     Margin="6, 0"
                     Style="{StaticResource IsFocusedTextStyle}"/>
             </HorizontalStackLayout>
-        </VerticalStackLayout>
+        <Label      
+                Text="Set to null"
+                Style="{StaticResource Headline}"/>
+        <DatePicker
+                x:Name="NullDatePicker"
+                Date="{x:Null}"/>
+        <Button Text="Set to null" Clicked="SetDatePickerToNull" />
+        <Button Text="Set to today" Clicked="SetDatePickerToToday" />
+    </VerticalStackLayout>
     </views:BasePage.Content>               
 </views:BasePage>

src/Controls/samples/Controls.Sample/Pages/Controls/DatePickerPage.xaml.cs

@@ -14,12 +14,12 @@ public DatePickerPage()
 			UpdateDatePickerBackground();
 		}
 
-		void OnUpdateBackgroundButtonClicked(object sender, System.EventArgs e)
+		void OnUpdateBackgroundButtonClicked(object sender, EventArgs e)
 		{
 			UpdateDatePickerBackground();
 		}
 
-		void OnClearBackgroundButtonClicked(object sender, System.EventArgs e)
+		void OnClearBackgroundButtonClicked(object sender, EventArgs e)
 		{
 			BackgroundDatePicker.Background = null;
 		}
@@ -41,14 +41,24 @@ void UpdateDatePickerBackground()
 			};
 		}
 
-		void OnFocusDatePickerFocused(object sender, Microsoft.Maui.Controls.FocusEventArgs e)
+		void OnFocusDatePickerFocused(object sender, FocusEventArgs e)
 		{
 			Debug.WriteLine("Focused");
 		}
 
-		void OnFocusDatePickerUnfocused(object sender, Microsoft.Maui.Controls.FocusEventArgs e)
+		void OnFocusDatePickerUnfocused(object sender, FocusEventArgs e)
 		{
 			Debug.WriteLine("Unfocused");
 		}
-	}
+
+		void SetDatePickerToNull(object sender, EventArgs e)
+		{
+			NullDatePicker.Date = null;
+		}
+
+		void SetDatePickerToToday(object sender, EventArgs e)
+		{
+			NullDatePicker.Date = DateTime.Now;
+		}
+    }
 }

src/Controls/src/Core/DateChangedEventArgs.cs

@@ -1,22 +1,30 @@
-#nullable disable
 using System;
 
-namespace Microsoft.Maui.Controls
+namespace Microsoft.Maui.Controls;
+
+/// <summary>
+/// Event arguments for <see cref="DatePicker.DateSelected" /> event.
+/// </summary>
+public class DateChangedEventArgs : EventArgs
 {
-	/// <include file="../../docs/Microsoft.Maui.Controls/DateChangedEventArgs.xml" path="Type[@FullName='Microsoft.Maui.Controls.DateChangedEventArgs']/Docs/*" />
-	public class DateChangedEventArgs : EventArgs
+	/// <summary>
+	/// Creates a new <see cref="DateChangedEventArgs" /> object that represents a change from <paramref name="oldDate" /> to <paramref name="newDate" />
+	/// </summary>
+	/// <param name="oldDate">The old date value.</param>
+	/// <param name="newDate">The new date value.</param>
+	public DateChangedEventArgs(DateTime? oldDate, DateTime? newDate)
 	{
-		/// <include file="../../docs/Microsoft.Maui.Controls/DateChangedEventArgs.xml" path="//Member[@MemberName='.ctor']/Docs/*" />
-		public DateChangedEventArgs(DateTime oldDate, DateTime newDate)
-		{
-			OldDate = oldDate;
-			NewDate = newDate;
-		}
+		OldDate = oldDate;
+		NewDate = newDate;
+	}
 
-		/// <include file="../../docs/Microsoft.Maui.Controls/DateChangedEventArgs.xml" path="//Member[@MemberName='NewDate']/Docs/*" />
-		public DateTime NewDate { get; private set; }
+	/// <summary>
+	/// The date that the user entered.
+	/// </summary>
+	public DateTime? NewDate { get; private set; }
 
-		/// <include file="../../docs/Microsoft.Maui.Controls/DateChangedEventArgs.xml" path="//Member[@MemberName='OldDate']/Docs/*" />
-		public DateTime OldDate { get; private set; }
-	}
+	/// <summary>
+	/// The date that was on the element at the time that the user selected it.
+	/// </summary>
+	public DateTime? OldDate { get; private set; }
 }