[HxInputDateRange] Using FluentValidationValidator to require non null value for HxDateTimeRange tries to create 2 spans with the same key.

[JoseTheChamp]

I have following code:

public class TimesheetsReportFilterModelValidator : AbstractValidator<TimesheetsReportFilterModel>
{
	public TimesheetsReportFilterModelValidator(Reports.Resources.ITimesheetsReportsFilterLocalizer timesheetsReportsFilterLocalizer)
	{
		RuleFor(m => m.Period).Must(period => period.StartDate.HasValue).When(m => m.PeriodStartRequired).WithMessage(timesheetsReportsFilterLocalizer.PeriodStartRequired);
		RuleFor(m => m.Period).Must(period => period.EndDate.HasValue).When(m => m.PeriodEndRequired).WithMessage(timesheetsReportsFilterLocalizer.PeriodEndRequired);
	}
}

Where property "Period" is of type DateTimeRange. Then i use this property and bind it to a HxDateTimeRange:
<HxInputDateRange InputSize="InputSize.Small" Label="@TimesheetsReportsFilterLocalizer.Period" @bind-Value="_model.Period" />
I then on initialization fill up these two fields, but when i clear one of those, then following error is thrown:

Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]
      Unhandled exception rendering component: More than one sibling of element 'span' has the same key value, 'Enter start date.'. Key values must be unique.
System.InvalidOperationException: More than one sibling of element 'span' has the same key value, 'Enter start date.'. Key values must be unique.
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.ThrowExceptionForDuplicateKey(Object key, RenderTreeFrame& frame)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.BuildKeyToInfoLookup(DiffContext diffContext, Int32 oldStartIndex, Int32 oldEndIndexExcl, Int32 newStartIndex, Int32 newEndIndexExcl)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForRange(DiffContext& diffContext, Int32 oldStartIndex, Int32 oldEndIndexExcl, Int32 newStartIndex, Int32 newEndIndexExcl)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForFramesWithSameSequence(DiffContext& diffContext, Int32 oldFrameIndex, Int32 newFrameIndex)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForRange(DiffContext& diffContext, Int32 oldStartIndex, Int32 oldEndIndexExcl, Int32 newStartIndex, Int32 newEndIndexExcl)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForFramesWithSameSequence(DiffContext& diffContext, Int32 oldFrameIndex, Int32 newFrameIndex)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForRange(DiffContext& diffContext, Int32 oldStartIndex, Int32 oldEndIndexExcl, Int32 newStartIndex, Int32 newEndIndexExcl)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.ComputeDiff(Renderer renderer, RenderBatchBuilder batchBuilder, Int32 componentId, ArrayRange`1 oldTree, ArrayRange`1 newTree)
   at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment, Exception& renderFragmentException)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.RenderInExistingBatch(RenderQueueEntry renderQueueEntry)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()

Note that the "Enter start date" in:

More than one sibling of element 'span' has the same key value, 'Enter start date.'

is the message passed to the AbstractValidator in WithMessage() method.

A potential solution to this problem could be for this component to implement its own null checking based on some parameter.

[hakenr]

This might relate to one of these root-causes:

• When used with DynamicComponent(.Net 6 feature) validation messages are getting duplicated Blazored/FluentValidation#93
• [Bug] FluentValidation never removed on FluentValidationValidator unloaded Blazored/FluentValidation#155
• InputBase should clear validation message store on Dispose for dynamic forms dotnet/aspnetcore#44531
  For now, I removed the @key in HxValidationMessage to not fail on duplicate messages (no matter where they come from):
  

[hakenr]

The InvalidOperationException during HxValidationMessage rendering was "fixed" in v4.3.5. It no longer fails on duplicate validation messages. It is out of scope of this issue where do the duplicate validation messages come from.