I could not find what is mistake in following code? - json

Question

Scenario:
I have following case class:
case class Student(firstName:String, lastName: String)
I need to write reads and writes for Student. The json I provide is Sequence of Student.
For Example:
{
"College": "Abc",
"student" : [{"firstName" : "Jack", "lastName":"Starc"},
{"firstName" : "Nicolas", "lastName":"Pooran"}
]
}
I have written my reads and writes as:
implicit val studentFormat = Json.format[Student]
implicit val studentRead = Json.reads[Student]
implicit val studentWrite = Json.writes[Student]
implicit val studentReadSeq = Reads.seq(studentRead)
implicit val studentWriteSeq = Writes.seq(studentWrite)
Now I have to make a type parser and check whether the student is array or simple object. Here key i.e. Student can be Students or StudentInfo. So I have to make a parser on the basis of value provided in json.
For this I have done as following:
def studentCheck(jsonValue: JsObject) = {
var modifiedJson = Json.obj()
for ((key, value) <- jsonValue.value) {
if(value.validate[Student].isSuccess ) {
val json =
studentFormat.writes(value.validate[Student].get).as[JsObject]
modifiedJson.+(key, json)
}
else if(studentReadSeq.reads(value).isSuccess) {
//My Code will be here
modifiedJson
}
else {
println("Error")
modifiedJson.+(key,value)
}
}
}
val studentJson = Json.obj(
"college" -> "ABC",
"student" -> Json.arr(
Json.obj("firstName" -> "Jack", "lastName" -> "Starc"),
Json.obj("firstName" -> "Nicolas", "entity" -> "Pooran")
)
)
studentCheck(studentJson)
The problem I get here is, even provided List of Students the first case i.e. if statement is executed instead of elseif. How can I validate so it satisfy all the condition, i.e if Student object is provided if statement is executed and if List of Student is provided elseif statement is executed.

Answer 1

You have a much better, safer, and functional way to validate a json.
Let's assume you have a College case class:
case class College(college: String, students: List[Student])
You can have a reader such as this:
object College{
implicit val collegeReads = Reads[College] = (
(JsPath \ "college").read[String] and
(JsPath \ "students").read[List[Student]
) (College.apply _)
}
Then in order to validate it, you can do:
def foo(jsonValue: JsObject)={
jsonValue.validate[College].fold(
errors => ,//handle parsing errors
collage => //your code when the parsing is successfull.
)
}