Add example for sorting by a dynamic Seq of columns

src/main/scala/com/typesafe/slick/examples/lifted/DynamicSorting.scala

@@ -0,0 +1,43 @@
+package com.typesafe.slick.examples.lifted
+import scala.slick.driver.H2Driver.simple._
+
+object DynamicSorting extends App {
+  object Suppliers extends Table[(Int, String, String, String, String, String)]("SUPPLIERS") {
+    def id = column[Int]("SUP_ID", O.PrimaryKey) // This is the primary key column
+    def name = column[String]("SUP_NAME")
+    def street = column[String]("STREET")
+    def city = column[String]("CITY")
+    def state = column[String]("STATE")
+    def zip = column[String]("ZIP")
+    def * = id ~ name ~ street ~ city ~ state ~ zip
+  }
+
+  Database.forURL("jdbc:h2:mem:test1", driver="org.h2.Driver") withSession { implicit session:Session =>
+    Suppliers.ddl.create
+    Suppliers.insert(101, "Acme, Inc.",      "99 Market Street", "Groundsville", "CA", "95199")
+    Suppliers.insert( 49, "Superior Coffee", "1 Party Place",    "Mendocino",    "CA", "95460")
+    Suppliers.insert(150, "The High Ground", "100 Coffee Lane",  "Meadows",      "CA", "93966")
+
+    // split string into useful pieces
+    def sortKeysFromString(sortString: String) = sortString.split(',').toList.map( _.split('.').map(_.toUpperCase).toList )
+
+    // apply sort keys as sortBy calls in reverse order
+    def sortKey[T](table : Table[T], sortKeys: List[Seq[String]]) : Query[_,T] = sortKeys match {
+      case key :: tail => 
+        sortKey( table, tail ).sortBy( _ =>
+          key match {
+            case name :: "ASC" :: Nil =>  table.column[String](name).asc
+            case name :: Nil =>           table.column[String](name).asc
+            case name :: "DESC" :: Nil => table.column[String](name).desc
+            case o => throw new Exception("invalid sorting key: "+o)
+          }
+        )
+      case Nil => Query(table)
+    }
+    println(
+      Query(Suppliers).flatMap(
+        table => sortKey(table, sortKeysFromString("street.desc,city.desc"))
+      ).selectStatement
+    )
+  }
+}