[SOLVED] Form tag helper generating a key-value pair in action

Form tag helper generating a key-value pair in action

I'm working on upgrading a .NET Framework 4.8 app to .NET Core 8.

Currently experiencing an issue where both Html.BeginForm and the form helper tag sometimes render the wrong action.

In Framework 4.8, I have a form like this:

<form method="post" action="/Controller/Action?paramOne=123">
  ...
</form>

In Core 8, the same form renders like this instead:

<form method="post" action="[paramOne, 123]">
  ...
</form>

I get this result with Html.BeginForm and also with <form asp-controller="Controller" asp-action="Action" method="post">.

What might be causing this result?

EDIT: after some more testing, I've found that this is happening even when I use the <!form></!form> opt out syntax; something is causing the form tag to be rewritten no matter what

Solution

I found the answer, and it was custom code in a layout:

The .cshtml filed I'd been editing had a form tag in it, but so did a parent layout, and that one had custom code to create the action parameter. That code was using Context.Request.Query, which renders its params as `[key, value]`.

I changed it to Context.Request.QueryString and got the result I was looking for.