Fix time/datetime-local binding with seconds when there's no step attribute

src/Components/Web.JS/src/Rendering/BrowserRenderer.ts

@@ -402,7 +402,7 @@ export class BrowserRenderer {
     let value = attributeFrame ? frameReader.attributeValue(attributeFrame) : null;
 
     if (value && element.tagName === 'INPUT') {
-      value = normalizeInputValue(value, element.getAttribute('type'));
+      value = normalizeInputValue(value, element);
     }
 
     switch (element.tagName) {
@@ -499,20 +499,23 @@ function parseMarkup(markup: string, isSvg: boolean) {
   }
 }
 
-function normalizeInputValue(value: string, type: string | null): string {
+function normalizeInputValue(value: string, element: Element): string {
   // Time inputs (e.g. 'time' and 'datetime-local') misbehave on chromium-based
   // browsers when a time is set that includes a seconds value of '00', most notably
   // when entered from keyboard input. This behavior is not limited to specific
   // 'step' attribute values, so we always remove the trailing seconds value if the
   // time ends in '00'.
+  // Similarly, if a time-related element doesn't have any 'step' attribute, browsers
+  // treat this as "round to whole number of minutes" making it invalid to pass any
+  // 'seconds' value, so in that case we strip off the 'seconds' part of the value.
 
-  switch (type) {
+  switch (element.getAttribute('type')) {
     case 'time':
-      return value.length === 8 && value.endsWith('00')
+      return value.length === 8 && (value.endsWith('00') || !element.hasAttribute('step'))
         ? value.substring(0, 5)
         : value;
     case 'datetime-local':
-      return value.length === 19 && value.endsWith('00')
+      return value.length === 19 && (value.endsWith('00') || !element.hasAttribute('step'))
         ? value.substring(0, 16)
         : value;
     default:

src/Components/test/E2ETest/Tests/BindTest.cs

@@ -2021,6 +2021,78 @@ public void CanBindTimeStepTextboxNullableTimeOnly()
         Assert.Equal(string.Empty, mirrorValue.GetAttribute("value"));
     }
 
+    [Fact]
+    public void CanBindDateTimeLocalDefaultStepTextboxDateTime()
+    {
+        // This test differs from the other "step"-related test in that the DOM element has no "step" attribute
+        // and hence defaults to step=60, and for this the framework has explicit logic to strip off the "seconds"
+        // part of the bound value (otherwise the browser reports it as invalid - issue #41731)
+
+        var target = Browser.Exists(By.Id("datetime-local-default-step-textbox-datetime"));
+        var boundValue = Browser.Exists(By.Id("datetime-local-default-step-textbox-datetime-value"));
+        var expected = DateTime.Now.Date.Add(new TimeSpan(8, 5, 0)); // Notice the "seconds" part is zero here, even though the original data has seconds=30
+        Assert.Equal(expected, DateTime.Parse(target.GetAttribute("value"), CultureInfo.InvariantCulture));
+
+        // Clear textbox; value updates to 00:00 because that's the default
+        target.Clear();
+        expected = default;
+        Browser.Equal(default, () => DateTime.Parse(target.GetAttribute("value"), CultureInfo.InvariantCulture));
+        Assert.Equal(default, DateTime.Parse(boundValue.Text, CultureInfo.InvariantCulture));
+
+        // We have to do it this way because the browser gets in the way when sending keys to the input element directly.
+        ApplyInputValue("#datetime-local-default-step-textbox-datetime", "2000-01-02T04:05");
+        expected = new DateTime(2000, 1, 2, 04, 05, 0);
+        Browser.Equal(expected, () => DateTime.Parse(boundValue.Text, CultureInfo.InvariantCulture));
+    }
+
+    [Fact]
+    public void CanBindTimeDefaultStepTextboxDateTime()
+    {
+        // This test differs from the other "step"-related test in that the DOM element has no "step" attribute
+        // and hence defaults to step=60, and for this the framework has explicit logic to strip off the "seconds"
+        // part of the bound value (otherwise the browser reports it as invalid - issue #41731)
+
+        var target = Browser.Exists(By.Id("time-default-step-textbox-datetime"));
+        var boundValue = Browser.Exists(By.Id("time-default-step-textbox-datetime-value"));
+        var expected = DateTime.Now.Date.Add(new TimeSpan(8, 5, 0)); // Notice the "seconds" part is zero here, even though the original data has seconds=30
+        Assert.Equal(expected, DateTime.Parse(target.GetAttribute("value"), CultureInfo.InvariantCulture));
+
+        // Clear textbox; value updates to 00:00 because that's the default
+        target.Clear();
+        expected = default;
+        Browser.Equal(DateTime.Now.Date, () => DateTime.Parse(target.GetAttribute("value"), CultureInfo.InvariantCulture));
+        Assert.Equal(default, DateTime.Parse(boundValue.Text, CultureInfo.InvariantCulture));
+
+        // We have to do it this way because the browser gets in the way when sending keys to the input element directly.
+        ApplyInputValue("#time-default-step-textbox-datetime", "04:05");
+        expected = DateTime.Now.Date.Add(new TimeSpan(4, 5, 0));
+        Browser.Equal(expected, () => DateTime.Parse(boundValue.Text, CultureInfo.InvariantCulture));
+    }
+
+    [Fact]
+    public void CanBindTimeDefaultStepTextboxTimeOnly()
+    {
+        // This test differs from the other "step"-related test in that the DOM element has no "step" attribute
+        // and hence defaults to step=60, and for this the framework has explicit logic to strip off the "seconds"
+        // part of the bound value (otherwise the browser reports it as invalid - issue #41731)
+
+        var target = Browser.Exists(By.Id("time-default-step-textbox-timeonly"));
+        var boundValue = Browser.Exists(By.Id("time-default-step-textbox-timeonly-value"));
+        var expected = new TimeOnly(8, 5, 0); // Notice the "seconds" part is zero here, even though the original data has seconds=30
+        Assert.Equal(expected, TimeOnly.Parse(target.GetAttribute("value"), CultureInfo.InvariantCulture));
+
+        // Clear textbox; value updates to 00:00 because that's the default
+        target.Clear();
+        expected = default;
+        Browser.Equal(default, () => TimeOnly.Parse(target.GetAttribute("value"), CultureInfo.InvariantCulture));
+        Assert.Equal(default, TimeOnly.Parse(boundValue.Text, CultureInfo.InvariantCulture));
+
+        // We have to do it this way because the browser gets in the way when sending keys to the input element directly.
+        ApplyInputValue("#time-default-step-textbox-timeonly", "04:05");
+        expected = new TimeOnly(4, 5, 0);
+        Browser.Equal(expected, () => TimeOnly.Parse(boundValue.Text, CultureInfo.InvariantCulture));
+    }
+
     // Applies an input through javascript to datetime-local/month/time controls.
     private void ApplyInputValue(string cssSelector, string value)
     {

src/Components/test/testassets/BasicTestApp/BindCasesComponent.razor

@@ -453,6 +453,25 @@
     <input id="time-step-textbox-nullable-timeonly-mirror" @bind="timeStepTextboxNullableTimeOnlyValue" @bind:format="HH:mm:ss" readonly />
 </p>
 
+<h3>datetime-local with no step attribute bound to a value with seconds</h3>
+<p>
+    DateTime:
+    <input id="datetime-local-default-step-textbox-datetime" @bind="timeStepTextboxDateTimeValue" type="datetime-local" />
+    <span id="datetime-local-default-step-textbox-datetime-value">@timeStepTextboxDateTimeValue</span>
+</p>
+
+<h3>time with no step attribute bound to a value with seconds</h3>
+<p>
+    DateTime:
+    <input id="time-default-step-textbox-datetime" @bind="timeStepTextboxDateTimeValue" type="time" />
+    <span id="time-default-step-textbox-datetime-value">@timeStepTextboxDateTimeValue</span>
+</p>
+<p>
+    TimeOnly:
+    <input id="time-default-step-textbox-timeonly" @bind="timeStepTextboxTimeOnlyValue" type="time" />
+    <span id="time-default-step-textbox-timeonly-value">@timeStepTextboxTimeOnlyValue.ToLongTimeString()</span>
+</p>
+
 @code {
     string textboxInitiallyBlankValue = null;
     string textboxInitiallyPopulatedValue = "Hello";