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我正在一个 Scala 项目中尝试使用 Slick 来访问关系（PostgreSQL）数据库。该项目使用 Scala 2.12.14、Slick 3.3.3 和 Slick Codegen 3.3.3。

我首先创建了一个非常简单的数据库表：

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

接下来，我运行了 Slick 代码生成器来为我生成Table和TableRow类。它们产生了这个 Scala 文件：

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))
}

据我所知，这似乎是有道理的。

然后我尝试实际使用此模式将记录插入“示例”表：

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

编译此代码失败：

方法 += 的参数过多 (2): (value: Tables.ExampleRow)slick.sql.FixedSqlAction[Int,slick.dbio.NoStream,slick.dbio.Effect.Write]

有任何想法吗？

4

1 回答 1

1

<>因为您有用于*投影的双向映射

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

那么以下应该工作

Tables.Example += ExampleRow(UUID.randomUUID(), Some("Whatever")),
于 2021-08-09T15:20:15.847 回答