How to convert Future[Seq[SomeClass]] to Json? - json

In Play framework I'm using Slick with MySQL database, how could I convert query result (Future[Seq[SomeClass]]) to Json for further usage in jQuery Autocomplete. I can serialize SomeClass , but where should I use .map(or something else) ?
Added:
Model:
package models
import play.api.libs.json._
case class Equipment(id: Long, name: String,area: String,kiMin: Double,kiMax: Double,cosFiMin: Double,cosFiMax: Double){
implicit val equipmentWrites = new Writes[Equipment] {
def writes(equipment: Equipment) = Json.obj(
"id" -> equipment.id,
"name" -> equipment.name,
"area" -> equipment.area,
"kiMin" -> equipment.kiMin,
"kiMax" -> equipment.kiMax,
"cosFiMin" -> equipment.cosFiMin,
"cosFiMax" -> equipment.cosFiMax
)
//also tried this for Seq
/* def writes(equipment: Equipment): JsValue = {
val equipmentSeq = Seq(
"id" -> JsNumber(equipment.id),
"name" -> JsString(equipment.name),
"area" -> JsString(equipment.area),
"kiMin" -> JsNumber(equipment.kiMin),
"kiMax" -> JsNumber(equipment.kiMax),
"cosFiMin" -> JsNumber(equipment.cosFiMin),
"cosFiMax" -> JsNumber(equipment.cosFiMax)
)
JsObject(equipmentSeq)
}*/
}
}
Controller:
def auto(term: String) = Action {
Ok(Json.toJson(equipmentDAO.get(term)))
}
DAO:
def get(name: String): Future[Seq[Equipment]] = db.run((equipment.filter { _.name === name }).result)
Added2:
controller method:
def auto(term: String) = Action.async {
val future: Future[Seq[Equipment]] = equipmentDAO.get(term)
future.map { seqOfSomeClass =>
Ok(Json.toJson(seqOfSomeClass))
}
}
Serializer:
implicit val equipmentWrites: Writes[Equipment] = (
(JsPath \ "id").write[Long] and
(JsPath \ "name").write[String] and
(JsPath \ "area").write[String] and
(JsPath \ "kiMin").write[Double] and
(JsPath \ "kiMax").write[Double] and
(JsPath \ "cosFiMin").write[Double] and
(JsPath \ "cosFiMax").write[Double]
)(unlift(Equipment.unapply))

Considering that you understand how Play Framework handles JSON and already have Reads and Writes for SomeClass, you can do something like this in your controller:
def someAction = Action.async {
val future: Future[Seq[SomeClass]] = ??? // get the future using Slick
future.map { seqOfSomeClass =>
Ok(Json.toJson(seqOfSomeClass))
}
}
This will serve a list of SomeClass in JSON.

Related

How could I properly work with Scala Play Read?

According to this documentation (official):
https://www.playframework.com/documentation/2.8.x/ScalaJsonCombinators
I have to create a case class, after that I have to create a JsonReader:
val nameReads: Reads[String] = (JsPath \ "name").read[String]
then
val nameResult: JsResult[String] = json.validate[String](nameReads)
So, the result would be into nameResult and it was expecting that data was accessible like this:
println(nameResult.name)
Unfortunately, it doesn't work. It doesn't print results or return them.
First of all I work with Future and read JSON from web
implicit val context = scala.concurrent.ExecutionContext.Implicits.global
val userReads: Reads[User] = (
(JsPath \ "id").read[Int] and
(JsPath \ "login").read[String]
)
val futureResult = wc.url(path).get().map {
response =>
response.json.validate[User](userReads)
}
futureResult.map(r => println(r.id, r.login))
But! This code works, but it isn't in documentation.
implicit val context = scala.concurrent.ExecutionContext.Implicits.global
val userReads: Reads[User] = (
(JsPath \ "id").read[Int] and
(JsPath \ "login").read[String]
)
val futureResult = wc.url(path).get().map {
response =>
UserTest(
(response.json \ "id").as[String],
(response.json \ "login").as[String]
)
}
futureResult.map(r => println(r.id, r.login))
Does somebody know why code into documentation doesn't work? What is wrong with it?
Could I use my code?
Calling validate[User] doesn't return a User but a JsResult[User]. This is because the JSON data might be invalid and your code needs to handle this case. There is an example in the documentation that you have linked to:
json.validate[Place] match {
case JsSuccess(place, _) => {
val _: Place = place
// do something with place
}
case e: JsError => {
// error handling flow
}
}

Scala Graph JSON with Play Framework

I am trying to pass in a POST request to a REST API developped with Play! (2.5) an object that I would like to use a Scala Graph (from the graph-core dependency).
It looks like the graph already has JSON serialization/deserialization methods based on lift-json, but I am not sure how to "plug" that into Play Json library. Until now I was using implicit converters (with Reads/Writes methods) but I would like to avoid having to write my own methods for the graph part since it is already part of the library itself.
For instance, let's say I have this code:
import java.util.UUID
import scalax.collection.Graph
case class Task(
id: UUID,
status: String)
case class Stuff(
id: UUID = UUID.randomUUID(),
name: String,
tasks: Option[Graph[Task, DiEdge]])
implicit val stuffWrites: Writes[Stuff] = (
(JsPath \ "id").write[UUID] and
(JsPath \ "name").write[String]
)(unlift(Stuff.unapply))
implicit val stuffReads: Reads[Stuff] = (
(JsPath \ "id").read[UUID] and
(JsPath \ "name").read[String]
)(Stuff.apply _)
implicit val taskWrite: Writes[Task] = (
(JsPath \ "id").write[UUID] and
(JsPath \ "status").write[String]
)(unlift(Task.unapply))
implicit val taskReads: Reads[Task] = (
(JsPath \ "id").read[UUID] and
(JsPath \ "status").read[String]
)(Task.apply _)
I miss the part to serialize the graph and the parenting. Should I rewrite everything from scratch, or can I rely on methods toJson/fromJson from scalax.collection.io.json ?
Since I struggled a bit to get this working, I thought I would share the code:
class UUIDSerializer extends Serializer[UUID] {
private val UUIDClass = classOf[UUID]
def deserialize(implicit format: Formats): PartialFunction[(TypeInfo, JValue), UUID] = {
case (TypeInfo(UUIDClass, _), json) => json match {
case JString(id) => UUID.fromString(id)
case x => throw new MappingException("Can't convert " + x + " to UUID")
}
}
def serialize(implicit format: Formats): PartialFunction[Any, JValue] = {
case x: UUID => JString(x.toString)
}
}
val extraSerializers = new UUIDSerializer :: Nil
implicit val formats = Serialization.formats(NoTypeHints) ++ extraSerializers
val taskDescriptor = new NodeDescriptor[Task](typeId = "Tasks", customSerializers=extraSerializers) {
def id(node: Any) = node match {
case Task(id, _) => id.toString
}
}
val quickJson = new Descriptor[Task](
defaultNodeDescriptor = taskDescriptor,
defaultEdgeDescriptor = Di.descriptor[Task]()
)
implicit val tasksWrites = new Writes[Graph[Task, DiEdge]] {
def writes(graph: Graph[Task, DiEdge]): JsValue = {
val json = graph.toJson(quickJson)
Json.parse(json.toString)
}
}
implicit val tasksReads = new Reads[Graph[Task, DiEdge]] {
def reads(json: JsValue): JsResult[Graph[Task, DiEdge]] = {
try {
val graph = Graph.fromJson[Task, DiEdge](json.toString, quickJson)
JsSuccess(graph)
}
catch {
case e: Exception =>
JsError(e.toString)
}
}
}
implicit def stuffModelFormat = Jsonx.formatCaseClass[Stuff]
You can try writing companion objects for yours case classes where you specify the formatting.
Example:
object Task {
implicit val taskModelFormat = Json.format[Task]
}
object Stuff {
implicit val staffModelFormat = Json.format[Stuff]
}
instead of the above implicits. With this solution compiler will resolve the known formatters for you and you could be only required to specify the missing/unknown types instead of the whole structure.

Applying conversion to play framework json element before applying to class

I have a class as so
case class Token(
creationDate: Date,
expires: Option[Date]
) {
def toJson(): String = Json.stringify(Json.toJson(this))
}
object Token {
def fromJson(json: String): Token = Json.parse(json).as[Token]
implicit val tokenReads: Reads[Token] = (
(JsPath \ "creation_date").read[Date] and
(JsPath \ "expires").readNullable[Date]
) (Token.apply _)
implicit val tokenWrites: Writes[Token] = (
(JsPath \ "creation_date").write[Date] and
(JsPath \ "expires").writeNullable[Date]
) (unlift(Token.unapply))
}
Which gets created from json like
{
"creation_date": "2014-05-22T08:05:57.556385+00:00",
"expires": null
}
Problem is that date format cant be converted to a date directly, I am looking to somehow take that string, and convert it using
DateFormat df2 = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSXXX");
String string2 = "2001-07-04T12:08:56.235-07:00";
Date result2 = df2.parse(string2);
and then pass it into the Token constructor, but I cant seem to figure out how to do that in the apply function
You can map String to Date if you have special date format
def strToDate(string2: String): Date = {
//... something such
val df2 = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSXXX");
df2.parse(string2);
}
implicit val tokenReads: Reads[Token] = (
(JsPath \ "creation_date").read[String].map(strToDate) and
(JsPath \ "expires").readNullable[String].map(_.map(strToDate))
) (Token.apply _)

Play 2 Json format, capture Int or String

I have a problem, I use an rest webservice than return an json not well formatted, sometimes return a string sometimes an integer in the same field. This is the code of the format:
implicit val ItemFormat: Format[Item] = (
(JsPath \ "a").format[String] and
(JsPath \ "b").format[String] and
(JsPath \ "c").formatNullable[String]
)(Item.apply , unlift(Item.unapply))
If c is empty or not exist or is a string works well, but if the c is an integer I have this error:
ValidationError(List(error.expected.jsstring),WrappedArray()))
I would obtain, if c is an integer, or convert it in a string or put c=None
You can do it this way.
case class Item(a: String, b: String, c: Option[String])
implicit val reads: Reads[A] = new Reads[A] {
override def reads(json: JsValue): JsResult[A] = {
for {
a <- (json \ "a").validate[String]
b <- (json \ "b").validate[String]
} yield {
val cValue = (json \ "c")
val cOptString = cValue.asOpt[String].orElse(cValue.asOpt[Int].map(_.toString))
Item(a, b, cOptString)
}
}
}

Create implicit json read for List collection which might be missing from input json

I am following play-salat (github.com/leon/play-salat) to create a model for a json input and save to mongodb. How can I create the implicit json read for List collection which might be missing in the input json? The following code gives me the validation error if the 'positions' is missing from input json.
case class LIProfile(
id: ObjectId = new ObjectId,
positions: List[Position] = Nil
)
object LIProfile extends LIProfileDAO with LIProfileJson
trait LIProfileDAO extends ModelCompanion[LIProfile, ObjectId] {
def collection = mongoCollection("liprofiles")
val dao = new SalatDAO[LIProfile, ObjectId](collection) {}
// Indexes
collection.ensureIndex(DBObject("emailAddress" -> 1), "li_profile_email", unique = true)
// Queries
def findOneByEmail(email: String): Option[LIProfile] = dao.findOne(MongoDBObject("emailAddress" -> email))
}
trait LIProfileJson {
implicit val liprofileJsonWrite = new Writes[LIProfile] {
def writes(p: LIProfile): JsValue = {
Json.obj(
"id" -> p.id,
"positions" -> p.positions
)
}
}
implicit val liprofileJsonRead = (
(__ \ 'id).read[ObjectId] ~
(__ \ 'positions).read (
(__ \ 'values).read[List[Position]]
)
)(LIProfile.apply _)
}
Use readNullable in order to retrieve an Option and map that to the contained list or the empty list.
implicit val liprofileJsonRead = (
(__ \ 'id).read[ObjectId] ~
(__ \ 'positions).readNullable (
(__ \ 'values).read[List[Position]]
).map {
case Some(l) => l
case None => Nil
}
)(LIProfile)
or even shorter:
implicit val liprofileJsonRead = (
(__ \ 'id).read[ObjectId] ~
(__ \ 'positions).readNullable (
(__ \ 'values).read[List[Position]]
).map { l => l.getOrElse(Nil) }
)(LIProfile)
I'm not quite sure what imports you really need here, my code compiles using:
import play.api.libs.json._
import play.api.libs.json.Reads._
import play.api.libs.functional.syntax._