Database connection pool example with c3p0

README.txt

@@ -27,3 +27,5 @@ of all available examples:
 
 * CallNativeDBFunction: Shows how to use a database function which is not
   provided by the SLICK driver in the Query Language.
+
+* ConnectionPool: Example of how to use Slick with a database connection pool

build.sbt

@@ -17,7 +17,8 @@ libraryDependencies ++= List(
   "com.typesafe.slick" %% "slick" % "1.0.0",
   "org.slf4j" % "slf4j-nop" % "1.6.4",
   "com.h2database" % "h2" % "1.3.170",
-  "org.xerial" % "sqlite-jdbc" % "3.6.20"
+  "org.xerial" % "sqlite-jdbc" % "3.6.20",
+  "c3p0" % "c3p0" % "0.9.1.2"
 /*
   "org.apache.derby" % "derby" % "10.6.1.0",
   "org.hsqldb" % "hsqldb" % "2.0.0",

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

@@ -0,0 +1,55 @@
+package com.typesafe.slick.examples.lifted
+
+import scala.slick.driver.PostgresDriver.simple._
+import Database.threadLocalSession
+import com.mchange.v2.c3p0.ComboPooledDataSource
+
+/* Connection pooling with c3p0 example.
+ * For a more detailed explanation see:
+ * http://fernandezpablo85.github.io/2013/04/07/slick_connection_pooling.html
+ */
+object ConnectionPool extends App {
+
+  case class User(id: Option[Int], name: String, last: String) {
+    override def toString = last + ", " + name
+  }
+
+  object Users extends Table[User]("users") {
+    def id = column[Int]("id", O.PrimaryKey, O.AutoInc)
+    def name = column[String]("name")
+    def lastName = column[String]("last_name")
+
+    def * = (id.? ~ name ~ lastName) <> (User, User.unapply _)
+  }
+
+  // the pool can be fully configured.
+  // http://www.mchange.com/projects/c3p0/
+  val datasource = new ComboPooledDataSource
+  datasource.setDriverClass("org.h2.Driver")
+  datasource.setJdbcUrl("jdbc:h2:mem:test1")
+
+  Database.forDataSource(datasource) withSession {
+
+    // create schema.
+    Users.ddl.create
+
+    // insert a few users.
+    Users.insert(User(None, "pablo", "fernandez"))
+    Users.insert(User(None, "noob", "saibot"))
+    Users.insert(User(None, "vincent", "vega"))
+
+    // query by last name.
+    val lastName = "fernandez"
+    val users = (for (u <- Users if u.lastName is lastName) yield (u)).list
+
+    // print results.
+    if (users.isEmpty)
+      println(s"no users with last name '$lastName'")
+    else {
+      println(s"users with last name '$lastName':")
+      users foreach { user =>
+        println(user)
+      }
+    }
+  }
+}