Unable to find Writable inside Action.async in play framework - scala

Question

Appears I am missing something but here is what I have got (posting only relevant piece). where MyService.save returns Future[Option[MyCompany] ].
def myPost = Action.async(parse.json) { request =>
val mn = Json.fromJson[MyEntity](request.body)
mn.map{
case m : MyEntity => MyService.save(m).map{f=>
f.map(mm=> Ok(mm ) )
}
}.recoverTotal {
e => Future { BadRequest("Detected error:" + JsError.toFlatJson(e)) }
}
}
Although I have defined
implicit val companyWriter: Writes[MyCompany] = (...)
And this implicit is in the scope, it shows compile error
Cannot write an instance of MyCompany to HTTP response. Try to define
a Writeable[MyCompany]
FYI: This writer is used elsewhere where I do Json.toJson(myCompany) and over there it finds and works fine.
Anything in particular to async Ok that it's missing?
EDIT
It appears that Ok() method cannot figure out the MyCompany needs to be transformed to json. following seems to have worked.
Ok(Json.toJson(mm) )
Is this because arguments to Ok can vary? Separately there are too many "map" in the above code. Any recommendation for improvement and making it more concise ?

Answer 1

Your compiler error is about a Writeable, not a Writes. Writeables are used to convert whatever you have to something that can be written to an HTTP response, Writes are used to marshall objects to JSON. The names can be a little confusing.
As for style...
def myPost = Action.async(parse.json) { request =>
request.body.validate[MyEntity] map { myEntity =>
MyService.save(myEntity).map { maybeCompany =>
maybeCompany match {
case Some(company) => Ok(Json.toJson(company))
case None => NoContent // or whatever's appropriate
}
}
} recoverTotal { t =>
Future { BadRequest("Detected error: " + JsError.toFlatJson(e)) }
}
}