Fix millisecond support in datetime columns. ODBC::Timestamp incorrectly takes SQL Server milliseconds and applies them as nanoseconds. We cope with this at the DBI layer by using SQLServerDBI::Type::SqlserverTimestamp class to parse the before type cast value appropriately. Also update the adapters #quoted_date method to work more simply by converting ruby's #usec milliseconds to SQL Server microseconds.

Author: metaskills

CHANGELOG

@@ -1,6 +1,11 @@
 
 MASTER
 
+* Fix millisecond support in datetime columns. ODBC::Timestamp incorrectly takes SQL Server milliseconds
+  and applies them as nanoseconds. We cope with this at the DBI layer by using SQLServerDBI::Type::SqlserverTimestamp 
+  class to parse the before type cast value appropriately. Also update the adapters #quoted_date method 
+  to work more simply by converting ruby's #usec milliseconds to SQL Server microseconds. [Ken Collins]
+
 * Core extensions for ActiveRecord now reflect on the connection before doing SQL Server things. Now 
   this adapter is compatible for using with other adapters. [Ken Collins]
 

lib/active_record/connection_adapters/sqlserver_adapter.rb

@@ -27,7 +27,7 @@ def self.sqlserver_connection(config) #:nodoc:
       conn["AutoCommit"] = true
       ConnectionAdapters::SQLServerAdapter.new(conn, logger, [driver_url, username, password])
     end
-   
+    
   end
 
   module ConnectionAdapters
@@ -264,7 +264,7 @@ def quoted_false
 
       def quoted_date(value)
         if value.acts_like?(:time) && value.respond_to?(:usec)
-          "#{super}.#{sprintf("%06d",value.usec)[0..2]}"
+          "#{super}.#{sprintf("%03d",value.usec/1000)}"
         else
           super
         end

lib/core_ext/dbi.rb

@@ -13,20 +13,24 @@ def to_sqlserver_string
     end
   end
 
-      
   module Type
 
     # Make sure we get DBI::Type::Timestamp returning a string NOT a time object
-    # that represents what is in the DB before type casting and let the adapter 
-    # do the reset. DBI::DBD::ODBC will typically return a string like:
+    # that represents what is in the DB before type casting while letting core 
+    # ActiveRecord do the reset. It is assumed that DBI is using ODBC connections 
+    # and that ODBC::Timestamp is taking the native milliseconds that SQL Server 
+    # stores and returning them incorrect using ODBC::Timestamp#fraction which is 
+    # nanoseconds. Below shows the incorrect ODBC::Timestamp represented by DBI 
+    # and the conversion we expect to have in the DB before type casting.
+    # 
     #   "1985-04-15 00:00:00 0"           # => "1985-04-15 00:00:00.000"
-    #   "2008-11-08 10:24:36 547000000"   # => "2008-11-08 10:24:36.547"
-    #   "2008-11-08 10:24:36 123000000"   # => "2008-11-08 10:24:36.000"
+    #   "2008-11-08 10:24:36 300000000"   # => "2008-11-08 10:24:36.003"
+    #   "2008-11-08 10:24:36 123000000"   # => "2008-11-08 10:24:36.123"
     class SqlserverTimestamp
       def self.parse(obj)
         return nil if ::DBI::Type::Null.parse(obj).nil?
-        date, time, fraction = obj.split(' ')
-        "#{date} #{time}.#{sprintf("%03d",fraction)}"
+        date, time, nanoseconds = obj.split(' ')
+        "#{date} #{time}.#{sprintf("%03d",nanoseconds.to_i/1000000)}"
       end
     end
 

test/cases/adapter_test_sqlserver.rb

@@ -199,22 +199,55 @@ def setup
   context 'For chronic data types' do
 
     context 'with a usec' do
-
+      
       setup do
         @time = Time.now
+        @db_datetime_003 = '2012-11-08 10:24:36.003'
+        @db_datetime_123 = '2012-11-08 10:24:36.123'
+        @all_datetimes = [@db_datetime_003, @db_datetime_123]
+        @all_datetimes.each do |datetime|
+          @connection.execute("INSERT INTO [sql_server_chronics] ([datetime]) VALUES('#{datetime}')")
+        end
       end
 
-      should 'truncate 123456 usec to just 123' do
-        @time.stubs(:usec).returns(123456)
-        saved = SqlServerChronic.create!(:datetime => @time).reload
-        assert_equal 123000, saved.datetime.usec
+      teardown do
+        @all_datetimes.each do |datetime|
+          @connection.execute("DELETE FROM [sql_server_chronics] WHERE [datetime] = '#{datetime}'")
+        end
       end
 
-      should 'drop 123 to 0' do
-        @time.stubs(:usec).returns(123)
-        saved = SqlServerChronic.create!(:datetime => @time).reload
-        assert_equal 0, saved.datetime.usec
-        assert_equal '000', saved.datetime_before_type_cast.split('.').last
+      context 'finding existing DB objects' do
+
+        should 'find 003 millisecond in the DB with before and after casting' do
+          existing_003 = SqlServerChronic.find_by_datetime!(@db_datetime_003)
+          assert_equal @db_datetime_003, existing_003.datetime_before_type_cast
+          assert_equal 3000, existing_003.datetime.usec, 'A 003 millisecond in SQL Server is 3000 milliseconds'
+        end
+
+        should 'find 123 millisecond in the DB with before and after casting' do
+          existing_123 = SqlServerChronic.find_by_datetime!(@db_datetime_123)
+          assert_equal @db_datetime_123, existing_123.datetime_before_type_cast
+          assert_equal 123000, existing_123.datetime.usec, 'A 123 millisecond in SQL Server is 123000 milliseconds'
+        end
+
+      end
+      
+      context 'saving new datetime objects' do
+
+        should 'truncate 123456 usec to just 123 in the DB cast back to 123000' do
+          @time.stubs(:usec).returns(123456)
+          saved = SqlServerChronic.create!(:datetime => @time).reload
+          assert_equal '123', saved.datetime_before_type_cast.split('.')[1]
+          assert_equal 123000, saved.datetime.usec
+        end
+        
+        should 'truncate 3001 usec to just 003 in the DB cast back to 3000' do
+          @time.stubs(:usec).returns(3001)
+          saved = SqlServerChronic.create!(:datetime => @time).reload
+          assert_equal '003', saved.datetime_before_type_cast.split('.')[1]
+          assert_equal 3000, saved.datetime.usec
+        end
+        
       end
 
     end