fixes bug where nullable values are not inserted in batch mode.

src/main/scala/net/noerd/prequel/Formattables.scala

@@ -31,7 +31,7 @@ class Nullable( val value: Option[ Formattable ] ) extends Formattable {
         value.map( _.escaped( formatter ) ).getOrElse( "null" )
     }
     override def addTo( statement: ReusableStatement ): Unit = {
-        statement.addNull
+        value.map(statement << _).getOrElse(statement.addNull)
     }
 }
 object Nullable {
@@ -184,4 +184,4 @@ class BinaryFormattable( val value: Array[Byte] ) extends Formattable {
 }
 object BinaryFormattable{
     def apply( value: Array[Byte] ) = new BinaryFormattable( value )
-}
+}

src/test/scala/net/noerd/prequel/TransactionSpec.scala

@@ -206,7 +206,31 @@ class TransactionSpec extends FunSpec with ShouldMatchers with BeforeAndAfterEac
                     difference should be > (1.0)
                 }
             }
+
+            it( "should handle nullable columns correctly" ) {
+                case class Item( v1: Long, v2: Option[String] )
+
+                val items = List( Item( 1001, Some( "foo" ) ), Item( 1002, None ) )
+                val strNullable = (x:Option[String]) => Nullable(x.map(StringFormattable(_)))
+
+                database.transaction { tx =>
+                    tx.executeBatch( "insert into transactionspec values(?, ?)" ) { statement =>
+                        items.foreach { item =>
+                          statement << item.v1 << Nullable(item.v2.map(StringFormattable(_))) <<!
+                        }
+                    }
+                }
+
+                database.transaction { tx =>
+                    val rs = tx.select( "select id, name from transactionspec where id > 1000" ) { row =>
+                        Item( row, row )
+                    }
+
+                    rs should contain (items.head)
+                    rs should contain (items.last)
+                }
+            }
 
         }
     }
-}
+}