Toggle disabled attribute on input field

Hello,

I need to toggle disabled attribute on an input field and have the following code:

def is_disabled(true, attrs), do: [{:disabled, true} | attrs]
def is_disabled(_, attrs), do: attrs

<%= form_for :price_form, "#", [phx_change: :price_change], fn f -> %>
     <%= text_input f, :price, is_disabled(true, [value: @total_price]) %>

The input field will be shown correctly - it will be disabled and the toggling will work. The problem is however that in the appropriate callback function, the form will just ignore that input field:

  def handle_event("price_change", params, socket) do
     IO.inspect params["price_form"]

The IO.inspect shows the following:

%{
  "comment" => "",
  "invoicing_entity" => "1",
}

All input fields are shown except for the :price one.

I confirmed that when I take out the toggling part, everything works fine.

Any help is highly appreciated!