tag helper [asp-for] for the input doesn't work with byte's array values (opposite to @Html.HiddenFor)

Question

When @Html.HiddenFor(e=>e.RowVersion) works well and generates:

<input id="RowVersion" name="RowVersion" type="hidden" value="AAAAAAAARlI=" /> 

But the tag helper version <input asp-for="@Model.RowVersion" name="RowVersion" hidden /> generates:

<input name="RowVersion" hidden id="RowVersion" value="System.Byte[]" />

Problem there is crazy value "System.Byte[]".

I want to keep using tag helper version for consistency. How I can enable bytes array serialization?

Answer 1

Use type="hidden" instead of hidden attribute!

You should be able to achieve the same thing if you do

/*
 *   From the ViewModel:
 *       byte[] RowVersion = Encoding.UTF8.GetBytes("FR")
 */
<input asp-for="RowVersion" type="hidden" />

Comparison

The reason (I am not 100% sure though)

Tag helper asp-for will try to generate the type for the HTML input based on the property type the tag helper binds to, when you don't specify a type attribute on the HTML input. If it can't find a proper type for the HTML input, it would default to type="text".

That's why your <input asp-for="RowVersion" hidden /> will generate a hidden textbox. Tag helper doesn't sanitize the input value when generating textbox:

But if you specify type="hidden" and your property type is byte[], it will actually do the Base64 encoding for you:

That's why @Html.HiddenFor() as well as <input type="hidden" asp-for= /> worked but the others didn't!