If you have used InputSelect in Blazor in ASP.NET Core 3.1 you may have noticed bind-Value only works on a limited set of types. That is strings and enum to be precise. In .NET 5 this will be improved. And it is easy to backport this to 3.1.

The problem

Look on this Blazor code:

Blazor sample 
<EditForm Model="@this">
    <label>Select:</label>
    <div>
        <InputSelect class="form-control" @bind-Value="@Id">
            <option value="0">Zero</option>
            <option value="1">One</option>
            <option value="2">Two</option>
        </InputSelect>
        <p>Selected ID: @Id</p>
    </div>
</EditForm>

@code {
    public int Id { get; set; }
}

This will show the user a drop list. And when the user changes value, the value of Id will be changed. Or, at least that is what we want. Instead an exception will be thrown with this message:

Exception 
InputSelect`1[System.Int32] does not support the type 'System.Int32'

Not pretty! The reason is that InputSelect only could convert the value if the id has the type string or some kind of enum.

The solution

This problem only exist in .NET Core 3.1. In the upcoming .NET 5 you could use int, byte, Guid and a lot more, both nullable and not, and it just works. Very nice! After this discovery I decided to investigate how this was solved and tried to backport this to 3.1.

This resulted in this code:

Solution code 
using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.Components.Forms;
using System;
using System.Globalization;

namespace MyNameSpace
{
    public class InputSelectExtended<T> : InputSelect<T>
    {
        protected override bool TryParseValueFromString(string value, out T result, out string validationErrorMessage)
        {
            try
            {
                if (BindConverter.TryConvertTo<T>(value, CultureInfo.CurrentCulture, out var parsedValue))
                {
                    result = parsedValue;
                    validationErrorMessage = null;
                    return true;
                }
                else
                {
                    result = default;
                    validationErrorMessage = "The chosen value is not valid.";
                    return false;
                }
            }
            catch (InvalidOperationException ex)
            {
                throw new InvalidOperationException($"{GetType()} does not support the type '{typeof(T)}'.", ex);
            }
        }
    }
}

Then I just needed to replace InputSelect with InputSelectExtended in the test application like this:

Blazor sample 
<EditForm Model="@this">
    <label>Select:</label>
    <div>
        <InputSelectExtended class="form-control" @bind-Value="@Id">
            <option value="0">Zero</option>
            <option value="1">One</option>
            <option value="2">Two</option>
        </InputSelectExtended>
        <p>Selected ID: @Id</p>
    </div>
</EditForm>

@code {
    public int Id { get; set; }
}

That is all. Short a simple and will save you from boring conversion code.

Summary

I cannot take much credit of this solution. This is a mix of code suggested in issue 11181, the code of InputSelect.cs and InputExtensions.cs in the aspnetcore repository on GitHub.