Converting JSON message to Groovy Bean

The power of the Java/Groovy type system, reflection API, and other goodies may be very handy if you need to make more type-safe code.

JSON by definition is not doing any type checking, but it is possible to map the JSON data to the Java/Groovy objects to present data inside your application and get access to type information. And that's what we will demonstrate in this recipe.

Getting ready

First of all let's define a Groovy Bean (POGO) class, which holds data representing some vehicle information:

package org.groovy.cookbook

import groovy.transform.ToString

@ToString
class Vehicle {

  static enum FuelType { DIESEL, PETROL, GAS, ELECTRIC }
  static enum TransmissionType { MANUAL, AUTOMATIC }

  @ToString
  static class Transmission {
    long gears
    TransmissionType type
  }

  String brand
  String model
  FuelType fuel
  Long releaseYear
  Transmission transmission

}

As you can notice it's nothing, but a set of fields of simple types, enumerations...