gistfile1.scala

//EXAMPLE evolution.scala


import java.io.{File, FilenameFilter}

import com.datastax.driver.core.Session
import org.apache.commons.io.filefilter.SuffixFileFilter
import org.joda.time.{DateTime, DateTimeZone}
import play.api.Play.current
import play.api.{Logger, Play}

import scala.collection.JavaConversions._
import scala.io.Source



trait Evolution{
  def evolve(session: Session)
}


object Evolutions {

  def migrate(session: Session): Unit = {

    Logger.info("Starting evolution check...")


    val initialTable =
      """
        |CREATE TABLE IF NOT EXISTS evolutions(
        |name text,
        |applied_date timestamp,
        |content text,
        |PRIMARY KEY (name))
      """.stripMargin

    session.execute(initialTable)

    val appliedSql = "select name from evolutions"
    val appliedEvolutions = session.execute(appliedSql).all().map(row => {
      row.getString(0)
    }).toSet

    Logger.debug(s"We found a total of ${appliedEvolutions.size} applied evolutions")


    //first apply cql evolutions
    val baseDirectory = Play.getExistingFile("conf/evolutions").getOrElse(sys.error("Unable to find file conf/evolutions"))
    val evolutions = baseDirectory.listFiles(new SuffixFileFilter("cql").asInstanceOf[FilenameFilter]).sorted
    evolutions.foreach(evolutionFile => {
      val evolutionName = parseEvolutionName(evolutionFile)
      if (appliedEvolutions.contains(evolutionName)) {
        Logger.debug(s"Skipping previously applied evolution $evolutionName")
      } else {
        Logger.info(s"Applying new evolution $evolutionName")
        val content = Source.fromFile(evolutionFile).mkString
        Source.fromFile(evolutionFile).getLines().filterNot(isComment).mkString("\n").split(";").map(_.trim).foreach(statement => {
          if (isInvalidStatement(statement)) {
            Logger.debug(s"Skipping invalid statement $statement")
          } else if (isExec(statement)){
            val className = statement.replaceAll("EXEC", "").trim
            Logger.debug(s"Executing class $className")
            val clazz = Class.forName(className)
            val instance = clazz.newInstance().asInstanceOf[Evolution]
            instance.evolve(session)
          } else {
            Logger.debug(s"Executing valid statement '$statement'")
            session.execute(statement)
            Thread.sleep(1000)
          }
        })

        Logger.debug("Saving applied evolution to database")
        val appliedDate = DateTime.now(DateTimeZone.UTC).toDate
        val insertStatement =
          """
            |INSERT INTO evolutions (name, applied_date, content) values (?, ?, ?)
          """.stripMargin
        session.execute(insertStatement, evolutionName, appliedDate, content)

      }
    })



    Logger.info(s"Completed evolution. We are now at version ${parseEvolutionName(evolutions.last)}")


  }

  private def isComment(statement: String): Boolean = {
    statement.startsWith("#")
  }

  private def isExec(statement : String) : Boolean = {
    statement.startsWith("EXEC")
  }

  private def isInvalidStatement(line: String): Boolean = {
    line.length == 0 || isComment(line)
  }

  private def parseEvolutionName(file : File) : String = {
    file.getName.split("\\.").head.toUpperCase
  }
}


//example file 2015-05-10.cql to be placed in /conf/evolutions
CREATE TABLE foobar (
	businessId uuid,
	createdDate timestamp,
	PRIMARY KEY(businessId)
) 
AND gc_grace_seconds = 3600;

ALTER TABLE zooRaw ADD newColumn boolean;

EXEC com.test.Evolution201505051625;

//sample file com.test.Evolution201505051625 to be placed in with the normal app and do code type migrations
package com.foo.evolutions

import com.datastax.driver.core.Session
import com.foo.Evolution

import scala.collection.JavaConversions._

class Evolution201505051625 extends Evolution {
   override def evolve(session: Session): Unit = {

     val emails = session.execute("select distinct email from users").all().map(row => {
       row.getString(0).trim
     })


     emails.map(email => {
       session.execute(s"update otherTableBar set last_name = 'Fred' where email = ?", email)
     })

   }
 }

ty