[DatePicker] Prevent silently ignoring date formatting failures

examples/Demo/Shared/Microsoft.FluentUI.AspNetCore.Components.xml

@@ -658,6 +658,11 @@
             If true, the ClassValue property will not include the EditContext's FieldCssClass.
             </summary>
         </member>
+        <member name="P:Microsoft.FluentUI.AspNetCore.Components.FluentInputBase`1.ParsingErrorMessage">
+            <summary>
+            Gets or sets the error message to show when the field can not be parsed.
+            </summary>
+        </member>
         <member name="P:Microsoft.FluentUI.AspNetCore.Components.FluentInputBase`1.EditContext">
             <summary>
             Gets the associated <see cref="T:Microsoft.AspNetCore.Components.Forms.EditContext"/>.
@@ -669,6 +674,12 @@
             Gets the <see cref="P:Microsoft.FluentUI.AspNetCore.Components.FluentInputBase`1.FieldIdentifier"/> for the bound value.
             </summary>
         </member>
+        <member name="P:Microsoft.FluentUI.AspNetCore.Components.FluentInputBase`1.FieldDisplayName">
+            <summary>
+            Gets the display name of the field, using the specified display name if set; otherwise, uses the field
+            identifier's name if the field is bound.
+            </summary>
+        </member>
         <member name="P:Microsoft.FluentUI.AspNetCore.Components.FluentInputBase`1.CurrentValue">
             <summary>
             Gets or sets the current value of the input.
@@ -8031,11 +8042,6 @@
             An Id value must be set to use this property.
             </summary>
         </member>
-        <member name="P:Microsoft.FluentUI.AspNetCore.Components.FluentNumberField`1.ParsingErrorMessage">
-            <summary>
-            Gets or sets the error message to show when the field can not be parsed.
-            </summary>
-        </member>
         <member name="P:Microsoft.FluentUI.AspNetCore.Components.FluentNumberField`1.ChildContent">
             <summary>
             Gets or sets the content to be rendered inside the component.
@@ -8047,6 +8053,11 @@
             unless an explicit value for Min or Max is provided.
             </summary>
         </member>
+        <member name="P:Microsoft.FluentUI.AspNetCore.Components.FluentNumberField`1.ParsingErrorMessage">
+            <summary>
+            Gets or sets the error message to show when the field can not be parsed.
+            </summary>
+        </member>
         <member name="M:Microsoft.FluentUI.AspNetCore.Components.FluentNumberField`1.FormatValueAsString(`0)">
             <summary>
             Formats the value as a string. Derived classes can override this to determine the formatting used for <c>CurrentValueAsString</c>.
@@ -8995,6 +9006,11 @@
             Fires when hovered value changes. Value will be null if no rating item is hovered.
             </summary>
         </member>
+        <member name="P:Microsoft.FluentUI.AspNetCore.Components.FluentRating.ParsingErrorMessage">
+            <summary>
+            Gets or sets the error message to show when the field can not be parsed.
+            </summary>
+        </member>
         <member name="P:Microsoft.FluentUI.AspNetCore.Components.FluentRating.GroupName">
             <summary />
         </member>

src/Core/Components/Base/FluentInputBase.cs

@@ -132,6 +132,12 @@ public abstract partial class FluentInputBase<TValue> : FluentComponentBase, IDi
     [Parameter]
     public virtual bool Embedded { get; set; } = false;
 
+    /// <summary>
+    /// Gets or sets the error message to show when the field can not be parsed.
+    /// </summary>
+    [Parameter]
+    public virtual string ParsingErrorMessage { get; set; } = "The {0} field must have a valid format.";
+
     /// <summary>
     /// Gets the associated <see cref="Microsoft.AspNetCore.Components.Forms.EditContext"/>.
     /// This property is uninitialized if the input does not have a parent <see cref="EditForm"/>.
@@ -145,6 +151,12 @@ public abstract partial class FluentInputBase<TValue> : FluentComponentBase, IDi
 
     internal virtual bool FieldBound => Field is not null || ValueExpression is not null || ValueChanged.HasDelegate;
 
+    /// <summary>
+    /// Gets the display name of the field, using the specified display name if set; otherwise, uses the field
+    /// identifier's name if the field is bound.
+    /// </summary>
+    internal string FieldDisplayName => DisplayName ?? (FieldBound ? FieldIdentifier.FieldName : UnknownBoundField);
+
     protected async Task SetCurrentValueAsync(TValue? value)
     {
         var hasChanged = !EqualityComparer<TValue>.Default.Equals(value, Value);

src/Core/Components/DateTime/FluentCalendar.razor.cs

@@ -293,9 +293,9 @@ private async Task PickerYearSelectAsync(DateTime? year)
     /// <summary />
     protected override bool TryParseValueFromString(string? value, out DateTime? result, [NotNullWhen(false)] out string? validationErrorMessage)
     {
-        BindConverter.TryConvertTo(value, Culture, out result);
-        validationErrorMessage = null;
-        return true;
+        bool success = BindConverter.TryConvertTo(value, Culture, out result);
+        validationErrorMessage = success ? null : string.Format(ParsingErrorMessage, FieldDisplayName);
+        return success;
     }
 
     /// <summary />

src/Core/Components/DateTime/FluentDatePicker.razor.cs

@@ -145,10 +145,9 @@ protected override bool TryParseValueFromString(string? value, out DateTime? res
             value = new DateTime(year, 1, 1).ToString(Culture.DateTimeFormat.ShortDatePattern);
         }
 
-        BindConverter.TryConvertTo(value, Culture, out result);
-
-        validationErrorMessage = null;
-        return true;
+        bool success = BindConverter.TryConvertTo(value, Culture, out result);
+        validationErrorMessage = success ? null : string.Format(ParsingErrorMessage, FieldDisplayName);
+        return success;
     }
 
     private string PlaceholderAccordingToView()

src/Core/Components/NumberField/FluentNumberField.razor.cs

@@ -86,12 +86,6 @@ public partial class FluentNumberField<TValue> : FluentInputBase<TValue>, IAsync
     [Parameter]
     public string? AutoComplete { get; set; }
 
-    /// <summary>
-    /// Gets or sets the error message to show when the field can not be parsed.
-    /// </summary>
-    [Parameter]
-    public string ParsingErrorMessage { get; set; } = "The {0} field must be a (valid) number.";
-
     /// <summary>
     /// Gets or sets the content to be rendered inside the component.
     /// </summary>
@@ -105,6 +99,11 @@ public partial class FluentNumberField<TValue> : FluentInputBase<TValue>, IAsync
     [Parameter]
     public bool UseTypeConstraints { get; set; }
 
+    /// <summary>
+    /// Gets or sets the error message to show when the field can not be parsed.
+    /// </summary>
+    public override string ParsingErrorMessage { get; set; } = "The {0} field must be a (valid) number.";
+
     private static readonly string _stepAttributeValue = GetStepAttributeValue();
 
     // If type constraints is true and min is null, set min to the minimum value of TValue.

src/Core/Components/Rating/FluentRating.razor.cs

@@ -74,6 +74,11 @@ public partial class FluentRating : FluentInputBase<int>
     [Parameter]
     public EventCallback<int?> OnHoverValueChanged { get; set; }
 
+    /// <summary>
+    /// Gets or sets the error message to show when the field can not be parsed.
+    /// </summary>
+    public override string ParsingErrorMessage { get; set; } = "The {0} field must be a number.";
+
     /// <summary />
     private string GroupName => Id ?? $"rating-{Id}";
 
@@ -90,8 +95,7 @@ protected override bool TryParseValueFromString(string? value, [MaybeNullWhen(fa
         }
         else
         {
-            validationErrorMessage = string.Format(CultureInfo.InvariantCulture,
-                                                   "The {0} field must be a number.",
+            validationErrorMessage = string.Format(ParsingErrorMessage,
                                                    FieldBound ? FieldIdentifier.FieldName : UnknownBoundField);
             return false;
         }

src/Core/Extensions/FluentInputExtensions.cs

@@ -42,7 +42,7 @@ internal static class FluentInputExtensions
             }
 
             result = default;
-            validationErrorMessage = $"The {input.DisplayName ?? (input.FieldBound ? input.FieldIdentifier.FieldName : input.UnknownBoundField)} field is not valid.";
+            validationErrorMessage = string.Format(input.ParsingErrorMessage, input.FieldDisplayName);
             return false;
         }
         catch (InvalidOperationException ex)

tests/Core/DateTime/FluentDatePickerTests.cs

@@ -2,6 +2,7 @@
 // This file is licensed to you under the MIT License.
 // ------------------------------------------------------------------------
 
+using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using Bunit;
 using Microsoft.AspNetCore.Components;
@@ -292,4 +293,42 @@ public void FluentDatePicker_OnDoubleClickEventTriggers()
         // Assert
         Assert.Equal(expected, actual);
     }
+
+    [Theory]
+    [InlineData("02-22-2000", "en-GB", "02/22/2000")]
+    [InlineData("02-22-2000", "nl-BE", null)]
+    [InlineData("22-12-2000", "nl-BE", "22/12/2000")]
+    [InlineData("02/22/2000", "en-GB", "02/22/2000")]
+    [InlineData("abc", "en-GB", null)]
+    [InlineData("02022000", "en-GB", null)]
+    public void FluentDatePicker_TryParseValueFromString(string? value, string? cultureName, string? expectedValue)
+    {
+        // Arrange
+        var picker = new TestDatePicker();
+        var culture = cultureName != null ? CultureInfo.GetCultureInfo(cultureName) : CultureInfo.InvariantCulture;
+
+        // Act
+        picker.Culture = culture;
+        var successfullParse = picker.CallTryParseValueFromString(value, out var resultDate, out var validationErrorMessage);
+
+        // Assert
+        if (successfullParse)
+        {
+            Assert.Equal(expectedValue, resultDate?.ToString(culture.DateTimeFormat.ShortDatePattern, culture));
+        }
+        else
+        {
+            Assert.Null(resultDate);
+            Assert.NotNull(validationErrorMessage);
+        }
+    }
+
+    // Temporary class to expose protected method
+    private class TestDatePicker : FluentDatePicker
+    {
+        public bool CallTryParseValueFromString(string? value, out System.DateTime? result, [NotNullWhen(false)] out string? validationErrorMessage)
+        {
+            return base.TryParseValueFromString(value, out result, out validationErrorMessage);
+        }
+    }
 }