处理非默认嵌套 Json 读取答案

【问题标题】：Handling non-default nested Json Reads处理非默认嵌套 Json 读取
【发布时间】：2019-05-26 08:34:09
【问题描述】：

所以我有以下 JSON：

{
  "senderEmail" : "sender@email.com",
  "recipientEmails" : ["first@email.com", "second@email.com"]
}

并希望将其映射到案例类：

case class Payload (senderEmail: String, recipientEmails: Seq[String])

使用带有电子邮件验证器的 Play 的 Json Reads。

虽然 senderEmail 微不足道，但我在使用 recipientEmails 时遇到了问题，因为它既是 Seq 又是电子邮件，所以这将不工作：

implicit val payloadRead: Reads[Payload] = (
    (JsPath \ "senderEmail").read[String](Reads.email) and
    (JsPath \ "recipientEmails").read[Seq[String]](Reads.seq))(Payload.apply _)

我收到overloaded method value read with alternatives。

那么我怎样才能将 Reads.seq 和 Reads.email 结合起来呢？

【问题讨论】：

标签： scala playframework play-json

【解决方案1】：

保持简单...

scala> import play.api.libs.json._

scala> import play.api.libs.functional.syntax._

scala> case class Payload (senderEmail: String, recipientEmails: Seq[String])
defined class Payload

scala> implicit val reads: Reads[Payload] = (
     |   (JsPath \ "senderEmail").read(Reads.email) and
     |   (JsPath \ "recipientEmails").read(Reads.seq(Reads.email))
     | )(Payload.apply _)
reads: play.api.libs.json.Reads[Payload] = play.api.libs.json.Reads$$...

scala> Json.parse("""{
     |   "senderEmail" : "sender@email.com",
     |   "recipientEmails" : ["first@email.com", "second@email.com"]
     | }""").validate[Payload]
res0: play.api.libs.json.JsResult[Payload] = JsSuccess(Payload(sender@email.com,Vector(first@email.com, second@email.com)),)

【讨论】：