Slick codegen & tables with > 22 columns

Question

I\'m new to Slick. I\'m creating a test suite for a Java application with Scala, ScalaTest and Slick. I\'m using slick to prepare data before the test and to do assertions o

Answer 1

Update 2019-02-15: *with the release of Slick 3.3.0, as answered by @Marcus there's built-in support for code generation of tables with > 22 columns.

As of Slick 3.2.0, the simplest solution for >22 param case class is to define the default projection in the * method using mapTo instead of the <> operator (per documented unit test):

case class BigCase(id: Int,
                   p1i1: Int, p1i2: Int, p1i3: Int, p1i4: Int, p1i5: Int, p1i6: Int,
                   p2i1: Int, p2i2: Int, p2i3: Int, p2i4: Int, p2i5: Int, p2i6: Int,
                   p3i1: Int, p3i2: Int, p3i3: Int, p3i4: Int, p3i5: Int, p3i6: Int,
                   p4i1: Int, p4i2: Int, p4i3: Int, p4i4: Int, p4i5: Int, p4i6: Int)

class bigCaseTable(tag: Tag) extends Table[BigCase](tag, "t_wide") {
      def id = column[Int]("id", O.PrimaryKey)
      def p1i1 = column[Int]("p1i1")
      def p1i2 = column[Int]("p1i2")
      def p1i3 = column[Int]("p1i3")
      def p1i4 = column[Int]("p1i4")
      def p1i5 = column[Int]("p1i5")
      def p1i6 = column[Int]("p1i6")
      def p2i1 = column[Int]("p2i1")
      def p2i2 = column[Int]("p2i2")
      def p2i3 = column[Int]("p2i3")
      def p2i4 = column[Int]("p2i4")
      def p2i5 = column[Int]("p2i5")
      def p2i6 = column[Int]("p2i6")
      def p3i1 = column[Int]("p3i1")
      def p3i2 = column[Int]("p3i2")
      def p3i3 = column[Int]("p3i3")
      def p3i4 = column[Int]("p3i4")
      def p3i5 = column[Int]("p3i5")
      def p3i6 = column[Int]("p3i6")
      def p4i1 = column[Int]("p4i1")
      def p4i2 = column[Int]("p4i2")
      def p4i3 = column[Int]("p4i3")
      def p4i4 = column[Int]("p4i4")
      def p4i5 = column[Int]("p4i5")
      def p4i6 = column[Int]("p4i6")

      // HList-based wide case class mapping
      def m3 = (
        id ::
        p1i1 :: p1i2 :: p1i3 :: p1i4 :: p1i5 :: p1i6 ::
        p2i1 :: p2i2 :: p2i3 :: p2i4 :: p2i5 :: p2i6 ::
        p3i1 :: p3i2 :: p3i3 :: p3i4 :: p3i5 :: p3i6 ::
        p4i1 :: p4i2 :: p4i3 :: p4i4 :: p4i5 :: p4i6 :: HNil
      ).mapTo[BigCase]

      def * = m3
}

EDIT

So, if you then want the slick-codegen to produce huge tables using the mapTo method described above, you override the relevant parts to the code generator and add in a mapTo statement:

package your.package
import slick.codegen.SourceCodeGenerator
import slick.{model => m}


class HugeTableCodegen(model: m.Model) extends SourceCodeGenerator(model) with GeneratorHelpers[String, String, String]{


  override def Table = new Table(_) {
    table =>

    // always defines types using case classes
    override def EntityType = new EntityTypeDef{
      override def classEnabled = true
    }

    // allow compound statements using HNil, but not for when "def *()" is being defined, instead use mapTo statement
    override def compoundValue(values: Seq[String]): String = {
      // values.size>22 assumes that this must be for the "*" operator and NOT a primary/foreign key
      if(hlistEnabled && values.size > 22) values.mkString("(", " :: ", s" :: HNil).mapTo[${StringExtensions(model.name.table).toCamelCase}Row]")
      else if(hlistEnabled) values.mkString(" :: ") + " :: HNil"
      else if (values.size == 1) values.head
      else s"""(${values.mkString(", ")})"""
    }

    // should always be case classes, so no need to handle hlistEnabled here any longer
    override def compoundType(types: Seq[String]): String = {
      if (types.size == 1) types.head
      else s"""(${types.mkString(", ")})"""
    }
  }
}

You then structure the codegen code in a separate project as documented so that it generates the source at compile time. You can pass your classname as an argument to the SourceCodeGenerator you're extending:

lazy val generateSlickSchema = taskKey[Seq[File]]("Generates Schema definitions for SQL tables")
generateSlickSchema := {

  val managedSourceFolder = sourceManaged.value / "main" / "scala"
  val packagePath = "your.sql.table.package"

  (runner in Compile).value.run(
    "slick.codegen.SourceCodeGenerator", (dependencyClasspath in Compile).value.files,
    Array(
      "env.db.connectorProfile",
      "slick.db.driver",
      "slick.db.url",
      managedSourceFolder.getPath,
      packagePath,
      "slick.db.user",
      "slick.db.password",
      "true",
      "your.package.HugeTableCodegen"
    ),
    streams.value.log
  )
  Seq(managedSourceFolder / s"${packagePath.replace(".","/")}/Tables.scala")
}