Scala converting Map[String, Long] into JSON or JSON string

Question

I have a this object:

case class UserStateSummaryByHourPayload (
        ownerid: String,
        userid: String,
        team: String,
        profile: String,
        day: String,
        hour: Int,
        sortdate: String,
        month: String,
        durationpayload: Map[String, Long],
        maxdurationpayload: Map[String, Long]
    )

I would like to turn the two Map attributes into JSON or a string (writing to mysql column) such as this

case class JunkTest (
        ownerid: String,
        userid: String,
        team: String,
        profile: String,
        day: String,
        hour: Int,
        sortdate: String,
        month: String,
        durationpayload: String,
        maxdurationpayload: String
    )

I tried to do something like this following some other peoples guides, but its not working:

import com.fasterxml.jackson.module.scala.DefaultScalaModule;
            import com.fasterxml.jackson.databind.ObjectMapper;

            @transient val mapper = new ObjectMapper();
            mapper.registerModule(DefaultScalaModule);

            var junktest = ussapayloads.map(a => new JunkTest(
                a.ownerid, 
                a.userid,
                a.team, 
                a.profile, 
                a.day, 
                a.hour, 
                a.sortdate, 
                a.month, 
                mapper.writeValueAsString(a.durationpayload),
                mapper.writeValueAsString(a.maxdurationpayload)
            ));

How to I take my Map[String, Long] and turn it into JSON or a JSON string?

Map("Online" -> 100,"Ready" -> 200)
{ "Online": 100, "Ready": 200 }

Raman Mishra · Accepted Answer · 2020-11-08 02:29:30Z

2

Here you go!

import spray.json._
import DefaultJsonProtocol._
object Demo1 extends App {
val keyValue = Map("Online" -> 100, "Ready" -> 200)
    
println(keyValue.toJson) //output {"Online":100,"Ready":200}
}

answered Nov 8, 2020 at 2:29

Raman Mishra

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Comments

Tomer Shetah · Accepted Answer · 2020-11-08 16:41:03Z

1

Using play-json it is really easy:

import play.api.libs.json.Json
Json.stringify(Json.toJsObject(Map("Online" -> 100, "Ready" -> 200)))

Code run can be found at Scastie;

BTW, the code you attached works completely fine. You can find it in Scastie.

In order to install play-json please add the following to your build.sbt:

resolvers += "play-json" at "https://mvnrepository.com/artifact/com.typesafe.play/play-json"
libraryDependencies += "com.typesafe.play" %% "play-json" % "2.9.1"

edited Nov 8, 2020 at 16:41

answered Nov 8, 2020 at 9:53

Tomer Shetah

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8 Comments

phattyD Over a year ago

I get exceptions with my above code: Caused by: java.io.NotSerializableException: com.fasterxml.jackson.module.paranamer.shaded.CachingParanamer

Tomer Shetah Over a year ago

@phattyD Are you sure? Do you have redundant imports? Can you reproduce this failure in Scastie?

phattyD Over a year ago

Yes I am sure, it works in Scastie, but does not work in my lab environment. I am trying implementations for the play-json and spray json now. Just trying to find the statements for adding to my sbt build to import the packages

Tomer Shetah Over a year ago

@phattyD, I added what you need in your build.sbt

phattyD Over a year ago

Thanks Tomer! I ended up with errors: Caused by: java.lang.ClassNotFoundException: play.api.libs.json.Writes I have tried importing play.api.libs.json._ and that didn't help. I had the same issues with the spray.json above. Is there a jar I need to add to classpath?

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