How to write Scala Play framework custom class's multiple JSON serializer deserializer?

Question

I have following class need to serializer deserializer

 case class User(userId: Int, userName: String, email: String,        
 password: String) {

 def this() = this(0, "", "", "")

def this(userId: Int){
this(userId, "", "", "" )
}

def this(userId: Int, userName: String){
  this(userId, userName, "", "" )
}

def this(userId: Int, userName: String, email: String){
  this(userId, userName,email, "" )
}

def this(password: String){
  this(0, "","", password )
 }
}

I have User case class with multiple constructor. So that User can be created as

var u = new User(mid, mname, memail, mpassword)
var u = new User(mid, mname)

I am expecting JSON request as

JSON request type 1:-

 "teamMembers" : [ {
    "userId" : 1,
    "userName" : "user name",
    "email" : "eamil",
    "password" : "password"
  }, {
    "userId" : 2,
    "userName" : "user name 2",
    "email" : "email2",
    "password" : "pssword"
  } ]

OR JSON request type 1:-

"teamMembers" : [ {
    "userId" : 1,
    "userName" : "user name"
  }, {
    "userId" : 2,
    "userName" : "user name 2"
  } ]

My implemented JSON serializer deserializer which is working fine as follows only for type one request

  trait UserJson extends Controller {
  implicit val userWrites: Writes[User] = (
      (__ \ "userId").write[Int] ~
      (__ \ "userName").write[String] ~
      (__ \ "email").write[String] ~
      (__ \ "password").write[String]
    )(unlift(User.unapply))

   implicit val userReads: Reads[User] = (
      (__ \ "userId").read[Int](min(0) keepAnd max(150)) ~
      (__ \ "userName").read[String](minLength[String](2)) ~
      (__ \ "email").read[String](minLength[String](2)) ~
      (__ \ "password").read[String](minLength[String](2))
    )(User.apply _)
}

But for type 2 JSON request is not working. Could you please let me know how to plement for for type 2 JSON request? Thanks in advance!

Lucky Libora · Accepted Answer · 2015-02-20 09:52:45Z

1

You can use Json Reads/Writes not as implicit value

For example:

Json.toJson(user)(userWrites1)
Json.toJson(user)(userWrites2)

answered Feb 20, 2015 at 9:52

Lucky Libora

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2 Comments

masiboo Over a year ago

what is userWrites1 and userWrites2? Is it something similar to my implemented userWrites or a new implementation or User class writter

Lucky Libora Over a year ago

userWrites1 is Writes for Json Request type 1

Vikas Pandya · Accepted Answer · 2015-02-20 13:55:58Z

0

Sounds like email and password are Optional. you can set email and password as Option and use writeNullable as shown below. is that what you are looking for?

on a side note: your this defs are looking odd, in Scala generally you use apply for achieving that.

case class User(userId: Int, userName: String, email: Option[String],  password: Option[String])

implicit val userWrites: Writes[User] = (
  (__ \ "userId").write[Int] ~
  (__ \ "userName").write[String] ~
  (__ \ "email").writeNullable[String] ~
  (__ \ "password").writeNullable[String]
)(unlift(User.unapply))

answered Feb 20, 2015 at 13:55

Vikas Pandya

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1 Comment

masiboo Over a year ago

I'm just learning scala. So don't know much. Could you please explain replace def this with apply. I need multiple constructor for User class. Could by all default value to null or 0 or only one of them provided. How to do it with apply? Thanks for the advise

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