Question

I have an EntityId class that servers as a simple wrapper class to database identifiers. The class already has methods for converting to and from a string representation. I’d like to use this string representation of the EntityId in my JSON web resources.

What’s the simplest to implement custom serialization for this simple type in Jackson? I know I can write a custom serializer and deserializer, but I wondered if there might be an even simpler solution.

Thanks!

Answer 1

If there is a method to serialize type as String, you can just add @JsonValue annotation like so:

public class MyClass {
  @JsonValue public String toString() { return "xxx"; }
}

Conversely, if there is a single-arg constructor that takes a String, int or long (or some Java type that Jackson can convert to from JSON Scalar type), you can add @JsonCreator annotation next to that constructor:

public class MyClass {
  @JsonCreator
  public MyClass(OtherPojo value) { // or use 'Map<String,Object>', extract data
      // ... 
  }
}