1 files changed, 13 insertions, 1 deletions
diff --git a/activerecord/lib/active_record/properties.rb b/activerecord/lib/active_record/properties.rb
index a5d724de0e..39c39ad9ff 100644
--- a/activerecord/lib/active_record/properties.rb
+++ b/activerecord/lib/active_record/properties.rb
@@ -64,7 +64,19 @@ module ActiveRecord
 
       # Returns an array of column objects for the table associated with this class.
       def columns
-        @columns ||= add_user_provided_columns(connection.schema_cache.columns(table_name))
+        @columns ||= add_user_provided_columns(connection.schema_cache.columns(table_name)).each do |column|
+          if Type::DecimalWithoutScale === column.cast_type
+            ActiveSupport::Deprecation.warn <<-MESSAGE.strip_heredoc
+              Decimal columns with 0 scale being automatically treated as integers
+              is deprecated, and will be removed in a future version of Rails. If
+              you'd like to keep this behavior, add
+
+                property :#{column.name}, Type::Integer.new
+
+              to your #{name} model.
+            MESSAGE
+          end
+        end
       end
 
       # Returns a hash of column objects for the table associated with this class.