scala - List[String] 的 QueryStringBinder

Question

使用 Play 2.0.1 我定义了以下路线:

GET  /demo/list controllers.Demos.listDemos(page: Int ?= 0, orderBy: Int ?= 1, nameFilter: String ?= "", versionFilter: Long ?= -1, tagFilter: List[String] ?= Nil)

但我在编译时收到此错误:

No QueryString binder found for type List[String]. Try to implement an implicit QueryStringBindable for this type.

我从 Play 2.1-RC(尚未正式发布)中找到可以解决问题的代码:

/**
* QueryString binder for List
*/
  implicit def bindableList[T: QueryStringBindable] = new QueryStringBindable[List[T]] {
    def bind(key: String, params: Map[String, Seq[String]]) = Some(Right(bindList[T](key, params)))
    def unbind(key: String, values: List[T]) = unbindList(key, values)
  }

  /**
* QueryString binder for java.util.List
*/
  implicit def bindableJavaList[T: QueryStringBindable] = new QueryStringBindable[java.util.List[T]] {
    def bind(key: String, params: Map[String, Seq[String]]) = Some(Right(bindList[T](key, params).asJava))
    def unbind(key: String, values: java.util.List[T]) = unbindList(key, values.asScala)
  }

  private def bindList[T: QueryStringBindable](key: String, params: Map[String, Seq[String]]): List[T] = {
    for {
      values <- params.get(key).toList
      rawValue <- values
      bound <- implicitly[QueryStringBindable[T]].bind(key, Map(key -> Seq(rawValue)))
      value <- bound.right.toOption
    } yield value
  }

  private def unbindList[T: QueryStringBindable](key: String, values: Iterable[T]): String = {
    (for (value <- values) yield {
      implicitly[QueryStringBindable[T]].unbind(key, value)
    }).mkString("&")
  }

但是经过几个小时的尝试，Play 仍然没有找到代码。我试过使用自定义对象和对该对象的隐式转换，但它仍然不起作用。

如何强制 Play 进行隐式转换？

更新

如果可能，我想避免使用 2.1-SNAPSHOT，因为我担心它的稳定性，但如果没有其他方法，我会使用它。我尝试了 4e6 的解决方案，但没有奏效:

[warn]  ::::::::::::::::::::::::::::::::::::::::::::::                                 
[warn]  ::          UNRESOLVED DEPENDENCIES         ::
[warn]  ::::::::::::::::::::::::::::::::::::::::::::::
[warn]  :: org.slf4j#slf4j-api;1.6.1: configuration not found in org.slf4j#slf4j-api;1.6.1: 'compile'. It was required from org.hibernate#hibernate-validator;4.2.0.Final compile
[warn]  :: commons-codec#commons-codec;1.4: configuration not found in commons-codec#commons-codec;1.4: 'compile'. It was required from org.apache.httpcomponents#httpclient;4.1.2 compile
[warn]  ::::::::::::::::::::::::::::::::::::::::::::::

我的 sbt 插件包含这个:

// Comment to get more information during initialization
logLevel := Level.Warn

// The Typesafe repository
resolvers ++= Seq(
  Resolver.url("Typesafe Ivy Snapshots", url("http://repo.typesafe.com/typesafe/ivy-snapshots/"))(Resolver.ivyStylePatterns),
  "Typesafe Releases" at "http://repo.typesafe.com/typesafe/releases/",
  "Typesafe Snapshots" at "http://repo.typesafe.com/typesafe/snapshots/",
  "DefaultMavenRepository" at "http://repo1.maven.org/maven2/",
  "JavaNet1Repository" at "http://download.java.net/maven/1/")

// Use the Play sbt plugin for Play projects
addSbtPlugin("play" % "sbt-plugin" % "2.1-SNAPSHOT")

Answer 1

我终于解决了。使用的代码是:

下 型号 , 文件 QueryBinders.scala :

package models

import play.api.mvc.{JavascriptLitteral, QueryStringBindable}


/**
 * Created with IntelliJ IDEA.
 * User: pvillega
 * Date: 07/05/12
 * Time: 12:06
 * QueryStringBinders for some data types missing in 2.0.1
 */
//TODO: remove when updating to 2.1
object QueryBinders {

  /**
   * QueryString binder for List
   */
  implicit def bindableList[T: QueryStringBindable] = new QueryStringBindable[List[T]] {
    def bind(key: String, params: Map[String, Seq[String]]) = Some(Right(bindList[T](key, params)))
    def unbind(key: String, values: List[T]) = unbindList(key, values)
  }

  private def bindList[T: QueryStringBindable](key: String, params: Map[String, Seq[String]]): List[T] = {
    for {
      values <- params.get(key).toList
      rawValue <- values
      bound <- implicitly[QueryStringBindable[T]].bind(key, Map(key -> Seq(rawValue)))
      value <- bound.right.toOption
    } yield value
  }

  private def unbindList[T: QueryStringBindable](key: String, values: Iterable[T]): String = {
    (for (value <- values) yield {
      implicitly[QueryStringBindable[T]].unbind(key, value)
    }).mkString("&")
  }

  /**
   * Convert a Scala List[T] to Javascript array
   */
  implicit def litteralOption[T](implicit jsl: JavascriptLitteral[T]) = new JavascriptLitteral[List[T]] {
    def to(value: List[T]) = "[" + value.map { v => jsl.to(v)+"," } +"]"
  }

}

上 Build.scala :

 val main = PlayProject(appName, appVersion, appDependencies, mainLang = SCALA).settings(
      // Add your own project settings here
      lessEntryPoints <<= baseDirectory(_ / "app" / "assets" / "stylesheets" ** "style.less"),
      routesImport += "models.QueryBinders"
    )

更新到 2.1 时必须将其删除，但它可以工作并且避免了我尝试将项目更新到 2.1 快照时遇到的所有问题。