Skip to content

Instantly share code, notes, and snippets.

@laser
Forked from davegurnell/BigData.scala
Created October 15, 2015 19:03
Show Gist options
  • Save laser/82d3052bff1c77145cd3 to your computer and use it in GitHub Desktop.
Save laser/82d3052bff1c77145cd3 to your computer and use it in GitHub Desktop.
Slick database mapping of >22 columns using HLists
import slick.driver.MySQLDriver.simple._
import scala.slick.collection.heterogenous._
import scala.slick.collection.heterogenous.syntax._
import scala.slick.jdbc._
// This is the large case class we are mapping -- 25 string fields:
case class BigData(
field1: String,
field2: String,
field3: String,
field4: String,
field5: String,
field6: String,
field7: String,
field8: String,
field9: String,
field10: String,
field11: String,
field12: String,
field13: String,
field14: String,
field15: String,
field16: String,
field17: String,
field18: String,
field19: String,
field20: String,
field21: String,
field22: String,
field23: String,
field24: String,
field25: String
)
// The remainder of the code demonstrates mapping the `BigData` class using Slick:
object ExampleQueries {
// This is the table for `BigData`. Because we have >22 fields,
// we have to use Slick's `HList` mappings:
class BigDataTable(tag: Tag) extends Table[BigData](tag, "bigdata") {
def field1 = column[String]("field1")
def field2 = column[String]("field2")
def field3 = column[String]("field3")
def field4 = column[String]("field4")
def field5 = column[String]("field5")
def field6 = column[String]("field6")
def field7 = column[String]("field7")
def field8 = column[String]("field8")
def field9 = column[String]("field9")
def field10 = column[String]("field10")
def field11 = column[String]("field11")
def field12 = column[String]("field12")
def field13 = column[String]("field13")
def field14 = column[String]("field14")
def field15 = column[String]("field15")
def field16 = column[String]("field16")
def field17 = column[String]("field17")
def field18 = column[String]("field18")
def field19 = column[String]("field19")
def field20 = column[String]("field20")
def field21 = column[String]("field21")
def field22 = column[String]("field22")
def field23 = column[String]("field23")
def field24 = column[String]("field24")
def field25 = column[String]("field25")
// The `*` projection uses `<>` to bidirectionally map the
// `HList` to a `BigData` object.
//
// For clarity I have separated the mapping functions out
// into separate methods below:
def * = (
field1 ::
field2 ::
field3 ::
field4 ::
field5 ::
field6 ::
field7 ::
field8 ::
field9 ::
field10 ::
field11 ::
field12 ::
field13 ::
field14 ::
field15 ::
field16 ::
field17 ::
field18 ::
field19 ::
field20 ::
field21 ::
field22 ::
field23 ::
field24 ::
field25 ::
HNil
) <> (createBigData, extractBigData)
// Here I'm defining the type of the HList so I don't have
// to write it inline in the method definitions below:
type BigDataHList =
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
String ::
HNil
// Mapping from HList to BigData:
def createBigData(data: BigDataHList): BigData = data match {
case field1 ::
field2 ::
field3 ::
field4 ::
field5 ::
field6 ::
field7 ::
field8 ::
field9 ::
field10 ::
field11 ::
field12 ::
field13 ::
field14 ::
field15 ::
field16 ::
field17 ::
field18 ::
field19 ::
field20 ::
field21 ::
field22 ::
field23 ::
field24 ::
field25 ::
HNil =>
BigData(field1, field2, field3, field4, field5, field6, field7, field8, field9, field10, field11, field12, field13, field14, field15, field16, field17, field18, field19, field20, field21, field22, field23, field24, field25)
}
// Mapping from BigData to HList:
def extractBigData(data: BigData): Option[BigDataHList] = data match {
case BigData(field1, field2, field3, field4, field5, field6, field7, field8, field9, field10, field11, field12, field13, field14, field15, field16, field17, field18, field19, field20, field21, field22, field23, field24, field25) =>
Some(
field1 ::
field2 ::
field3 ::
field4 ::
field5 ::
field6 ::
field7 ::
field8 ::
field9 ::
field10 ::
field11 ::
field12 ::
field13 ::
field14 ::
field15 ::
field16 ::
field17 ::
field18 ::
field19 ::
field20 ::
field21 ::
field22 ::
field23 ::
field24 ::
field25 ::
HNil
)
}
}
// Query singleton:
val BigDataTable = TableQuery[BigDataTable]
// And finally an example query. The important thing
// here is that this returns a `List[BigData]` (and type checks):
def findBigDataByField1(field1: String)(implicit session: Session): List[BigData] =
BigDataTable.filter(_.field1 === field1).list
}
name := "bigdata"
scalaVersion := "2.11.2"
libraryDependencies ++= Seq(
"com.typesafe.slick" %% "slick" % "2.1.0",
"org.slf4j" % "slf4j-nop" % "1.6.4"
)
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment