"ambiguous reference to overloaded definition" 对于 Anorm 的含义

Question

我最近开始学习 Scala 和 Play Framework，在学习 Anorm documention for the Play Framework 时，我得到了以下代码片段：

import anorm.SqlParser.str

val id: List[String] = 
  SQL("insert into City(name, country) values ({name}, {country})")
 .on('name -> "Cambridge", 'country -> "New Zealand")
 .executeInsert(str.+) // insertion returns a list of at least one string keys

并遇到编译错误：

ambiguous reference to overloaded definition, both method str in object SqlParser of type (columnPosition: Int)(implicit c: anorm.Column[String])anorm.RowParser[String] and method str in object SqlParser of type (columnName: String)(implicit c: anorm.Column[String])anorm.RowParser[String] match expected type ?

我正在使用带有 PostgreSQL 数据库的常规 Scala Play 种子并修改了 HomeController 索引操作：

package controllers
import play.api.Play.current
import javax.inject._
import play.api._
import play.api.mvc._
import play.api.db.{ Database, NamedDatabase, DB }
import anorm._
import anorm.SqlParser.str

@Singleton
class HomeController @Inject()() extends Controller { 

  def index = Action {
   DB.withConnection { implicit c =>
     val id: List[String] = 
       SQL("insert into City(name, country) values ({name}, {country})")
       .on('name -> "Cambridge", 'country -> "New Zealand")
       .executeInsert(str.+) // insertion returns a list of at least one string keys  
     Ok("Result is: " + id)
   }       
  }

}

以下是构建依赖项：

libraryDependencies ++= Seq(
  jdbc,
  cache,
  ws,
  "org.scalatestplus.play" %% "scalatestplus-play" % "1.5.1" % Test,
  "com.typesafe.play" %% "anorm" % "2.5.0",
  "org.postgresql"     %  "postgresql" % "9.3-1102-jdbc41"
)

有什么问题？

Answer 1

您误用了 .str，必须使用列位置或列名称调用它，以便将如此引用的列解析为字符串。

"ambiguous reference to overloaded definition" 对于 Anorm 的含义

Meaning of "ambiguous reference to overloaded definition" for Anorm

scala

anorm