Simple CRUD with Scala and Playframework - json

Question

Technology stack: Scala, PlayFramework 2.3.8, MongoDB ( Salat + casbah ).
I am developing some restful APIs, with simple CRUD.
The entity:
case class Company(
_id: ObjectId = new ObjectId,
user_id: Any = "",
cinema_id: Int = 0,
name: String = "",
status: String = "",
releaseId: Int, fileId: Int,
date: CompanyDate,
showTime: List[Int] = List())
case class CompanyDate(start: DateTime, end: DateTime)
I create Reads for creating the object from JSON:
def createFromJson(json: JsValue, user: User): Reads[Company] = {
val user_id = (for {
cinema_id <- (json \ "cinema_id").asOpt[Int]
cinema <- user.cinema.find(_.id == cinema_id)
} yield cinema.getUser(user._id.toString)
).getOrElse(0)
(
Reads.pure(new ObjectId) and
Reads.pure[Any](user_id).filter(ValidationError("You have no access to this cinema"))(_ != 0) and
(__ \ "cinema_id").read[Int] and
(__ \ "name").read[String](minLength[String](1) keepAnd maxLength[String](100)) and
Reads.pure[String]("new") and
(__ \ "release_id").read[Int] and
(__ \ "file_id").read[Int] and
(__ \ "date").read[CompanyDate] and
(__ \ "show_time").read[List[Int]](minLength[List[Int]](1))
)(Company.apply _).flatMap(company => Reads { _ =>
if (company.date.start isAfter company.date.end) {
JsError(JsPath \ "date" \ "start" -> ValidationError("Start < end"))
} else {
JsSuccess(company)
}
})
}
It took me create wrapped function to pass user to Reads, because some field ( user_id ) calculate from current user - client doesn't know this information.
It looks a little ugly, but works ok.
The Controller for create action is very simple, it takes json, casts it to class and saves to DB.
Next thing: Update. In update method i want reuse some validation cases ( check date.start < date.end, e.g. ), but i don't receive the full object. My client only sends me changed fields.
Some fields ( cinema_id and user_id ) can only be set when creating object, they can't be updated.
Example request (UPDATED):
PUT /api/company/1
{
"name": "Name",
"status": "delete"
}
How can i validate this json and update existing object?
What is the best approach to solve this task?