Blazor: Support generating ID attributes based on the binding expression similar to how Name attributes are already generated about aspnetcore

[VahidN]

This is how I do it in my custom components to access the HtmlFieldName:

public class BlazorHtmlField<T> : InputBase<T>
{
    public BlazorHtmlField(Expression<Func<T>> valueExpression)
    {
        ValueExpression = valueExpression;
        _ = base.SetParametersAsync(ParameterView.FromDictionary(new Dictionary<string, object?>()));
        HtmlFieldName = NameAttributeValue;
    }

    public string HtmlFieldName { get; private set; }

    protected override bool TryParseValueFromString(string? value, out T result, out string validationErrorMessage)
        => throw new NotImplementedException();
}

Usage:

<label for="@ValueField.HtmlFieldName">

@code {
   private BlazorHtmlField<string?> ValueField => new(ValueExpression);

   [Parameter] public Expression<Func<string?>> ValueExpression { get; set; } = default!;
   [Parameter] public string? Value { get; set; }
}

[chrischu]

@VahidN That's a pretty clever workaround, I can probably apply that in my codebase. However, it would still be cool if there was a properly supported way to do that :).

[chrischu]

In the end I found a pretty good workaround:

@using System.Diagnostics.CodeAnalysis

@typeparam TValue
@inherits InputBase<TValue>

@ControlTemplate(new ControlContext { Id = NameAttributeValue })

@code {

  [Parameter, EditorRequired]
  public RenderFragment<ControlContext> ControlTemplate { get; set; } = null!;

  protected override bool TryParseValueFromString (string? value, [MaybeNullWhen(false)] out TValue result, [NotNullWhen(false)] out string? validationErrorMessage) {
    throw new NotImplementedException();
  }

}

It can be used like this:

<ControlContextProvider Value="Value" ValueChanged="ValueChanged" ValueExpression="ValueExpression">
  <ControlTemplate>
    @context.Id
  </ControlTemplate>
</ControlContextProvider>