Rounding errors w/datetime2(0) types having no fractional seconds. Fixes #465.

Thanks @alawton

Author: metaskills

CHANGELOG.md

@@ -5,6 +5,7 @@
 * Undefined method `database_prefix_remote_server?' Fixes #450. Thanks @jippeholwerda
 * Document two methods for avoiding N'' quoting on char/varchar columns.
 * First run failure of `change_column` while dropping constraint. Fixes #420. Thanks @GrumpyRainbow @rkr090
+* Rounding errors w/datetime2(0) types having no fractional seconds. Fixes #465. Thanks @alawton
 
 #### Changed
 

Gemfile

@@ -52,6 +52,7 @@ group :development do
   gem 'mocha'
   gem 'minitest', '< 5.3.4' # PENDING: [Rails5.x] Remove test order constraint.
   gem 'minitest-spec-rails'
+  gem 'pry'
 end
 
 group :guard do

lib/active_record/connection_adapters/sqlserver/type/time_value_fractional.rb

@@ -9,9 +9,13 @@ module TimeValueFractional
 
           def cast_fractional(value)
             return value if !value.respond_to?(fractional_property) || value.send(fractional_property).zero?
-            seconds = value.send(fractional_property).to_f / fractional_operator.to_f
-            seconds = ((seconds * (1 / fractional_precision)).round / (1 / fractional_precision)).round(fractional_scale)
-            frac_seconds = (seconds * fractional_operator).to_i
+            frac_seconds = if fractional_scale == 0
+                             0
+                           else
+                             seconds = value.send(fractional_property).to_f / fractional_operator.to_f
+                             seconds = ((seconds * (1 / fractional_precision)).round / (1 / fractional_precision)).round(fractional_scale)
+                             (seconds * fractional_operator).to_i
+                           end
             value.change fractional_property => frac_seconds
           end
 

test/cases/column_test_sqlserver.rb

@@ -373,6 +373,13 @@ def assert_obj_set_and_save(attribute, value)
       obj.datetime2_1.must_equal time.change(nsec: 100000000), "Nanoseconds were <#{obj.datetime2_1.nsec}> vs <100000000>"
       obj.save! ; obj.reload
       obj.datetime2_1.must_equal time.change(nsec: 100000000), "Nanoseconds were <#{obj.datetime2_1.nsec}> vs <100000000>"
+      col = column('datetime2_0')
+      col.cast_type.precision.must_equal 0
+      time = Time.utc 2016, 4, 19, 16, 45, 40, 771036
+      obj.datetime2_0 = time
+      obj.datetime2_0.must_equal time.change(nsec: 0), "Nanoseconds were <#{obj.datetime2_0.nsec}> vs <0>"
+      obj.save! ; obj.reload
+      obj.datetime2_0.must_equal time.change(nsec: 0), "Nanoseconds were <#{obj.datetime2_0.nsec}> vs <0>"
     end
 
     it 'datetimeoffset' do

test/schema/datatypes/2012.sql

@@ -28,6 +28,7 @@ CREATE TABLE [sst_datatypes] (
   [datetime2_7] [datetime2](7) NULL DEFAULT '9999-12-31 23:59:59.9999999',
   [datetime2_3] [datetime2](3) NULL,
   [datetime2_1] [datetime2](1) NULL,
+  [datetime2_0] [datetime2](0) NULL,
   [datetimeoffset_7] [datetimeoffset](7) NULL DEFAULT '1984-01-24 04:20:00.1234567 -08:00',
   [datetimeoffset_3] [datetimeoffset](3) NULL,
   [datetimeoffset_1] [datetimeoffset](1) NULL,