How to Encode and Decode JSON with Scala-Circe

If you are new to the Scala-Circe library and you want to know how to decode/encode JSON, follow the method below.

Your Classes

Assume your application has a nested class named Person which has a member named address of class Address.

case class Address(doorNo: Int, street: String, city: String, zipCode: String)
case class Person(name: String, age: Int, address: Address)

Your Task

You need to encode objects and decode text using Circe and use them following some business logic.

What to do?

I will give you a simple straightforward approach that will work for 95% of your use cases.

1. Add implicit codec in companion objects for your case classes.

2. Add encode and decode method in the companion object.

import io.circe._, io.circe.generic.semiauto._, io.circe.syntax._

case class Address(doorNo: Int, street: String, city: String, zipCode: String)
object Address {
  implicit val codec = deriveCodec[Address]
}

case class Person(name: String, age: Int, address: Address)

object Person {
  implicit val codec = deriveCodec[Person]
  def encode(person: Person): String = {
    person.asJson.toString
  }

  def decode(jsonString: String): Person = {
    parser.decode[Person](jsonString).toOption.get
  }
}

That’s it. You can now use the Person.encode and Person.decode methods.

The sample app is below.

import io.circe._, io.circe.generic.semiauto._, io.circe.syntax._

val johnDoe = Person("John Doe", 24, Address(5, "Times Square Street", "New York", "12345"))
println(Person.encode(johnDoe))


val encodedText = """
{
  "name" : "Fin",
  "age" : 21,
  "address" : {
    "doorNo" : 7,
    "street" : "Staten Island",
    "city" : "New York",
    "zipCode" : "23456"
  }
}
"""
val decodedJohnDoe = Person.decode(encodedText)

println(decodedJohnDoe)

If you want to access the runnable version of this code, along with imports and library version, use scastie link.

First published here