Don't convert dates to strings when using prepared statements in mysql

Dates are able to be natively handled by the mysql2 gem. libmysql (and
the wire protocol) represent each portion of the date as an integer,
which is significantly faster to encode and decode. By passing the Ruby
date objects through directly, we can save a good bit of time and
memory.

2 files changed, 19 insertions, 3 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/mysql/quoting.rb b/activerecord/lib/active_record/connection_adapters/mysql/quoting.rb
index d4f5906b33..0cc0ac74fe 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/quoting.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/quoting.rb
@@ -39,6 +39,14 @@ module ActiveRecord
         def quoted_binary(value)
           "x'#{value.hex}'"
         end
+
+        def _type_cast(value)
+          case value
+          when Type::Time::Value then value.__getobj__
+          when Date, Time then value
+          else super
+          end
+        end
       end
     end
   end
diff --git a/activerecord/test/cases/quoting_test.rb b/activerecord/test/cases/quoting_test.rb
index b21adccc4b..98b20915c6 100644
--- a/activerecord/test/cases/quoting_test.rb
+++ b/activerecord/test/cases/quoting_test.rb
@@ -174,13 +174,21 @@ module ActiveRecord
 
       def test_type_cast_date
         date = Date.today
-        expected = @conn.quoted_date(date)
+        if current_adapter?(:Mysql2Adapter)
+          expected = date
+        else
+          expected = @conn.quoted_date(date)
+        end
         assert_equal expected, @conn.type_cast(date)
       end
 
       def test_type_cast_time
         time = Time.now
-        expected = @conn.quoted_date(time)
+        if current_adapter?(:Mysql2Adapter)
+          expected = time
+        else
+          expected = @conn.quoted_date(time)
+        end
         assert_equal expected, @conn.type_cast(time)
       end
 
@@ -257,7 +265,7 @@ module ActiveRecord
 
         def test_type_cast_ar_object
           value = DatetimePrimaryKey.new(id: @time)
-          assert_equal "2017-02-14 12:34:56.789000",  @connection.type_cast(value)
+          assert_equal @connection.type_cast(value.id),  @connection.type_cast(value)
         end
       end
     end