Allow multiparameter assigned attributes to be used with `text_field`

Between 4.2 and 5.0 the behavior of how multiparameter attributes
interact with `_before_type_cast` changed. In 4.2 it returns the
post-type-cast value. After 5.0, it returns the hash that gets sent to
the type. This behavior is correct, but will cause an issue if you then
tried to render that value in an input like `text_field` or
`hidden_field`.

In this case, we want those fields to use the post-type-cast form,
instead of the `_before_type_cast` (the main reason it uses
`_before_type_cast` at all is to avoid losing data when casting a
non-numeric string to integer).

I've opted to modify `came_from_user?` rather than introduce a new
method for this as I want to avoid complicating that contract further,
and technically the multiparameter hash didn't come from assignment, it
was constructed internally by AR.

Close #27888.

activemodel/lib/active_model/type/helpers/accepts_multiparameter_time.rb

@@ -21,6 +21,10 @@ def initialize(defaults: {})
             end
           end
 
+          define_method(:value_constructed_by_mass_assignment?) do |value|
+            value.is_a?(Hash)
+          end
+
           define_method(:value_from_multiparameter_assignment) do |values_hash|
             defaults.each do |k, v|
               values_hash[k] ||= v

activemodel/lib/active_model/type/value.rb

@@ -86,6 +86,10 @@ def changed_in_place?(raw_old_value, new_value)
         false
       end
 
+      def value_constructed_by_mass_assignment?(_value) # :nodoc:
+        false
+      end
+
       def map(value) # :nodoc:
         yield value
       end

activerecord/CHANGELOG.md

@@ -1,3 +1,8 @@
+*   Values constructed using multi-parameter assignment will now use the
+    post-type-cast value for rendering in single-field form inputs.
+
+    *Sean Griffin*
+
 *   `Relation#joins` is no longer affected by the target model's
     `current_scope`, with the exception of `unscoped`.
 

activerecord/lib/active_record/attribute.rb

@@ -174,7 +174,7 @@ def type_cast(value)
         end
 
         def came_from_user?
-          true
+          !type.value_constructed_by_mass_assignment?(value_before_type_cast)
         end
       end
 

activerecord/test/cases/multiparameter_attributes_test.rb

@@ -383,4 +383,15 @@ def test_multiparameter_assignment_of_aggregation_with_large_index
 
     assert_equal("address", ex.errors[0].attribute)
   end
+
+  def test_multiparameter_assigned_attributes_did_not_come_from_user
+    topic = Topic.new(
+      "written_on(1i)" => "1952",
+      "written_on(2i)" => "3",
+      "written_on(3i)" => "11",
+      "written_on(4i)" => "13",
+      "written_on(5i)" => "55",
+    )
+    refute_predicate topic, :written_on_came_from_user?
+  end
 end