Scala Play:使用可选字段实现自定义 QueryStringBindable
Scala Play: Implement custom QueryStringBindable with an optional field
我在 Play 框架 (2.8.1) 中使用 Scala,并且有一个 Sort
class 用于捕获基于 sort 的查询字符串参数。示例 url:http://myurl:9000?sortBy=name&sortOrder=asc
。此处,sortOrder
字段是可选的,如果未提供,则默认值为 "asc"
。我已经实现了自己的 QueryStringBindable
class 如下:
object Sort {
val asc = "asc"
implicit def queryStringBinder(implicit stringBinder: QueryStringBindable[String]) = new QueryStringBindable[Sort] {
override def bind(key: String, params: Map[String, Seq[String]]): Option[Either[String, Sort]] = {
for {
sortBy <- stringBinder.bind("sortBy", params)
if(params.contains("sortOrder")) {sortOrder <- stringBinder.bind("sortOrder", params)}
} yield {
(sortBy, sortOrder) match {
case (Right(sortBy), Right(sortOrder)) => Right(Sort(sortBy, Some(sortOrder)))
case _ => Left("Unable to bind Sort")
}
}
}
override def unbind(key: String, sort: Sort): String = {
stringBinder.unbind("sortBy", sort.sortBy) + "&" + stringBinder.unbind("sortOrder", sort.sortOrder.getOrElse(asc))
}
}
}
case class Sort(sortBy: String, sortOrder: Option[String] = Some(Sort.asc))
但是,如果 url 的查询字符串中没有提供任何内容,我将无法使用默认值捕获可选字段 sortOrder
。我希望 http://myurl:9000?sortBy=name
仍然按升序排序(默认),即使未提供 &sortOrder
。
不使用 for comprehension 可能更容易:
object Sort {
val asc = "asc"
implicit def queryStringBinder(implicit stringBinder: QueryStringBindable[String]) = new QueryStringBindable[Sort] {
override def bind(key: String, params: Map[String, Seq[String]]): Option[Either[String, Sort]] = {
val sortBy = stringBinder.bind("sortBy", params) // Option[Either[String, String]]
val sortOrder = stringBinder.bind("sortOrder", params) // Option[Either[String, String]]
val result = // Either[String, Sort]
(sortBy, sortOrder) match {
case (Some(Right(field)), Some(Right(order))) => Right(Sort(field, Some(order)))
case (Some(Right(field)), None) => Right(Sort(field))
case _ => Left("Unable to bind Sort")
}
Option(result)
}
override def unbind(key: String, sort: Sort): String = {
stringBinder.unbind("sortBy", sort.sortBy) + "&" + stringBinder.unbind("sortOrder", sort.sortOrder.getOrElse(asc))
}
}
}
case class Sort(sortBy: String, sortOrder: Option[String] = Some(Sort.asc))
我在 Play 框架 (2.8.1) 中使用 Scala,并且有一个 Sort
class 用于捕获基于 sort 的查询字符串参数。示例 url:http://myurl:9000?sortBy=name&sortOrder=asc
。此处,sortOrder
字段是可选的,如果未提供,则默认值为 "asc"
。我已经实现了自己的 QueryStringBindable
class 如下:
object Sort {
val asc = "asc"
implicit def queryStringBinder(implicit stringBinder: QueryStringBindable[String]) = new QueryStringBindable[Sort] {
override def bind(key: String, params: Map[String, Seq[String]]): Option[Either[String, Sort]] = {
for {
sortBy <- stringBinder.bind("sortBy", params)
if(params.contains("sortOrder")) {sortOrder <- stringBinder.bind("sortOrder", params)}
} yield {
(sortBy, sortOrder) match {
case (Right(sortBy), Right(sortOrder)) => Right(Sort(sortBy, Some(sortOrder)))
case _ => Left("Unable to bind Sort")
}
}
}
override def unbind(key: String, sort: Sort): String = {
stringBinder.unbind("sortBy", sort.sortBy) + "&" + stringBinder.unbind("sortOrder", sort.sortOrder.getOrElse(asc))
}
}
}
case class Sort(sortBy: String, sortOrder: Option[String] = Some(Sort.asc))
但是,如果 url 的查询字符串中没有提供任何内容,我将无法使用默认值捕获可选字段 sortOrder
。我希望 http://myurl:9000?sortBy=name
仍然按升序排序(默认),即使未提供 &sortOrder
。
不使用 for comprehension 可能更容易:
object Sort {
val asc = "asc"
implicit def queryStringBinder(implicit stringBinder: QueryStringBindable[String]) = new QueryStringBindable[Sort] {
override def bind(key: String, params: Map[String, Seq[String]]): Option[Either[String, Sort]] = {
val sortBy = stringBinder.bind("sortBy", params) // Option[Either[String, String]]
val sortOrder = stringBinder.bind("sortOrder", params) // Option[Either[String, String]]
val result = // Either[String, Sort]
(sortBy, sortOrder) match {
case (Some(Right(field)), Some(Right(order))) => Right(Sort(field, Some(order)))
case (Some(Right(field)), None) => Right(Sort(field))
case _ => Left("Unable to bind Sort")
}
Option(result)
}
override def unbind(key: String, sort: Sort): String = {
stringBinder.unbind("sortBy", sort.sortBy) + "&" + stringBinder.unbind("sortOrder", sort.sortOrder.getOrElse(asc))
}
}
}
case class Sort(sortBy: String, sortOrder: Option[String] = Some(Sort.asc))