Too many arguments for method += with Slick-generated code

Question

I'm trying out Slick in a Scala project to access a relational (PostgreSQL) database. The project uses Scala 2.12.14, Slick 3.3.3 and Slick Codegen 3.3.3.

I've started by creating a very simple database table:

create table example (
    id uuid not null primary key,
    name varchar
);

Next, I've run the Slick codegen to generate the Table and TableRow classes for me. They result in this Scala file:

object Tables extends {
  val profile = slick.jdbc.PostgresProfile
} with Tables

/** Slick data model trait for extension, choice of backend or usage in the cake pattern. (Make sure to initialize this late.) */
trait Tables {
  val profile: slick.jdbc.JdbcProfile
  import profile.api._
  import slick.model.ForeignKeyAction
  // NOTE: GetResult mappers for plain SQL are only generated for tables where Slick knows how to map the types of all columns.
  import slick.jdbc.{GetResult => GR}

  /** DDL for all tables. Call .create to execute. */
  lazy val schema: profile.SchemaDescription = Example.schema
  @deprecated("Use .schema instead of .ddl", "3.0")
  def ddl = schema

  /** Entity class storing rows of table Example
   *  @param id Database column id SqlType(uuid), PrimaryKey
   *  @param name Database column name SqlType(varchar), Default(None) */
  case class ExampleRow(id: java.util.UUID, name: Option[String] = None)
  /** GetResult implicit for fetching ExampleRow objects using plain SQL queries */
  implicit def GetResultExampleRow(implicit e0: GR[java.util.UUID], e1: GR[Option[String]]): GR[ExampleRow] = GR{
    prs => import prs._
    ExampleRow.tupled((<<[java.util.UUID], <<?[String]))
  }
  /** Table description of table example. Objects of this class serve as prototypes for rows in queries. */
  class Example(_tableTag: Tag) extends profile.api.Table[ExampleRow](_tableTag, "example") {
    def * = (id, name) <> (ExampleRow.tupled, ExampleRow.unapply)
    /** Maps whole row to an option. Useful for outer joins. */
    def ? = ((Rep.Some(id), name)).shaped.<>({r=>import r._; _1.map(_=> ExampleRow.tupled((_1.get, _2)))}, (_:Any) =>  throw new Exception("Inserting into ? projection not supported."))

    /** Database column id SqlType(uuid), PrimaryKey */
    val id: Rep[java.util.UUID] = column[java.util.UUID]("id", O.PrimaryKey)
    /** Database column name SqlType(varchar), Default(None) */
    val name: Rep[Option[String]] = column[Option[String]]("name", O.Default(None))
  }
  /** Collection-like TableQuery object for table Example */
  lazy val Example = new TableQuery(tag => new Example(tag))
}

From what I can tell, this seems to make sense.

Then I've tried to actually use this schema to insert a record into the "example" table:

val config = DatabaseConfig.forURI[JdbcProfile](URI.create("...not relevant..."))
config.db.run(DBIO.seq(
    Tables.Example += (UUID.randomUUID(), "Whatever"),
))

Compiling this code fails with:

too many arguments (2) for method +=: (value: Tables.ExampleRow)slick.sql.FixedSqlAction[Int,slick.dbio.NoStream,slick.dbio.Effect.Write]

Any ideas?

Yuriy Tumakha Yuriy Tumakha · Accepted Answer · 2021-08-09T15:20:15

As you have bidirectional mapping using <> for the * projection

def * = (id, name) <> (ExampleRow.tupled, ExampleRow.unapply)

then the following should work

Tables.Example += ExampleRow(UUID.randomUUID(), Some("Whatever")),

Too many arguments for method += with Slick-generated code

1 Answers