QueryStringBindable for Map[String, String] and Map[String, List[String]]

Application.scala

import play.api.mvc.QueryStringBindable
import play.api.mvc.{Action, Controller}

/**
  * Created by flo on 6/19/2016.
  */
object Binders {

  implicit def queryMapBinder(implicit stringBinder: QueryStringBindable[String]) = new QueryStringBindable[Map[String, String]] {
    override def bind(key: String, params: Map[String, Seq[String]]): Option[Either[String, Map[String, String]]] = {
      val data = for {
        (k, ps) <- params
        if k startsWith key
        p <- ps
      } yield (k.drop(key.length + 1), p)
      if (data.isEmpty) {
        None
      } else {
        Some(Right(data))
      }
    }

    override def unbind(key: String, map: Map[String, String]): String = {
      map.map(x => stringBinder.unbind(s"${key}.${x._1}", x._2)).foldLeft("")((a, b) => a + b + "&")
    }

    override def javascriptUnbind() =
      s"""function(k,v) {\n
          var res = "";\n
          v.forEach(function(entry) {\n
              res += encodeURIComponent(k+'.'+entry.key)+'='+entry.data+'&';\n
          });\n
          return res;\n
        }"""
  }

  implicit def queryMapListBinder(implicit stringBinder: QueryStringBindable[String]) = new QueryStringBindable[Map[String, List[String]]] {
    override def bind(key: String, params: Map[String, Seq[String]]): Option[Either[String, Map[String, List[String]]]] = {
      val data = for {
        (k, ps) <- params
        if k startsWith key
        p <- ps
      } yield (k.drop(key.length + 1), p.split(',').toList)
      if (data.isEmpty) {
        None
      } else {
        Some(Right(data))
      }
    }

    override def unbind(key: String, map: Map[String, List[String]]): String = {
      map.map(x => stringBinder.unbind(s"${key}.${x._1}", x._2.foldLeft("")((a,b) => a + b + ','))).foldLeft("")((a, b) => a + b + "&")
    }

     override def javascriptUnbind() =
      s"""function(k,v) {\n
          var res = "";\n
          v.forEach(function(entry) {\n
              var data = "";\n
              entry.data.forEach(function(x) {\n
                data += x + ',';\n
              });\n
              res += encodeURIComponent(k+'.'+entry.key)+'='+data.substr(0,data.length-1)+'&';\n
          });\n
          res.substr(0,res.length-1);\n
          return res;\n
        }"""
  }
}


// --- Usage
object Application extends Controller {

  /* Example of request the action:
   * http://localhost:9000/?map.a=val1&map.b=val2&mapList.a=1,2,3&mapList.b=4,5,6
   */
  def index(map: Map[String,String], mapList: Map[String,List[String]]) = Action {
    Ok(views.html.index(map, mapList))
  }

}