allow structs as param values in used_input? check (#3762)

Closes #3757.

Author: SteffenDE

lib/phoenix_component.ex

@@ -1697,10 +1697,17 @@ defmodule Phoenix.Component do
     unused_field_str = "_unused_#{field}"
 
     case params do
-      %{^field_str => _, ^unused_field_str => _} -> false
-      %{^field_str => %{} = nested} -> Enum.any?(Map.keys(nested), &used_param?(nested, &1))
-      %{^field_str => _val} -> true
-      %{} -> false
+      %{^field_str => _, ^unused_field_str => _} ->
+        false
+
+      %{^field_str => %{} = nested} when not is_struct(nested) ->
+        Enum.any?(Map.keys(nested), &used_param?(nested, &1))
+
+      %{^field_str => _val} ->
+        true
+
+      %{} ->
+        false
     end
   end
 

test/phoenix_component_test.exs

@@ -335,13 +335,15 @@ defmodule Phoenix.ComponentUnitTest do
       "bday" => %{"day" => "", "month" => "", "year" => ""},
       "published_at" => %{"date" => "", "time" => "", "_unused_date" => "", "_unused_time" => ""},
       "deleted_at" => %{},
-      "inserted_at" => %{"date" => "", "time" => "", "_unused_time" => ""}
+      "inserted_at" => %{"date" => "", "time" => "", "_unused_time" => ""},
+      "date" => DateTime.utc_now()
     }
 
     form = to_form(params, as: "profile", action: :validate)
     assert used_input?(form[:bday])
     refute used_input?(form[:published_at])
     refute used_input?(form[:deleted_at])
     assert used_input?(form[:inserted_at])
+    assert used_input?(form[:date])
   end
 end