3 files changed, 40 insertions, 2 deletions
diff --git a/activemodel/CHANGELOG.md b/activemodel/CHANGELOG.md
index 2dfde11707..909fbe512b 100644
--- a/activemodel/CHANGELOG.md
+++ b/activemodel/CHANGELOG.md
@@ -1,6 +1,21 @@
 ## Rails 5.2.0.beta2 (November 28, 2017) ##
 
-*   No changes.
+*  Return correct date while converting parameters in `value_from_multiparameter_assignment`
+    for `ActiveModel::Type::Date`
+
+    Before:
+
+        Day.new({"day(1i)"=>"1", "day(2i)"=>"1", "day(3i)"=>"1"})
+        => #<Day id: nil, day: "0001-01-03", created_at: nil, updated_at: nil>
+
+    After:
+
+        Day.new({"day(1i)"=>"1", "day(2i)"=>"1", "day(3i)"=>"1"})
+        => #<Day id: nil, day: "0001-01-01", created_at: nil, updated_at: nil>
+
+    Fixes #28521
+
+    *Sayan Chakraborty*
 
 
 ## Rails 5.2.0.beta1 (November 27, 2017) ##
diff --git a/activemodel/lib/active_model/type/date.rb b/activemodel/lib/active_model/type/date.rb
index 8cecc16d0f..edc408f541 100644
--- a/activemodel/lib/active_model/type/date.rb
+++ b/activemodel/lib/active_model/type/date.rb
@@ -17,6 +17,18 @@ module ActiveModel
         value.to_s(:db).inspect
       end
 
+      def is_utc?
+        ::Time.zone_default.nil? || ::Time.zone_default =~ "UTC"
+      end
+
+      def default_timezone
+        if is_utc?
+          :utc
+        else
+          :local
+        end
+      end
+
       private
 
         def cast_value(value)
@@ -49,7 +61,7 @@ module ActiveModel
 
         def value_from_multiparameter_assignment(*)
           time = super
-          time && time.to_date
+          time && new_date(time.year, time.mon, time.mday)
         end
     end
   end
diff --git a/activemodel/test/cases/type/date_test.rb b/activemodel/test/cases/type/date_test.rb
index e8cf178612..c50a549d3d 100644
--- a/activemodel/test/cases/type/date_test.rb
+++ b/activemodel/test/cases/type/date_test.rb
@@ -15,6 +15,17 @@ module ActiveModel
         date_string = ::Time.now.utc.strftime("%F")
         assert_equal date_string, type.cast(date_string).strftime("%F")
       end
+
+      def test_returns_correct_year
+        type = Type::Date.new
+
+        time = ::Time.utc(1, 1, 1)
+        date = ::Date.new(time.year, time.mon, time.mday)
+
+        values_hash_for_multiparameter_assignment = { 1 => 1, 2 => 1, 3 => 1 }
+
+        assert_equal date, type.cast(values_hash_for_multiparameter_assignment)
+      end
     end
   end
 end