Jackson: Deserialize to a Map with correct type for each value

Question

I have a class that looks like the following

public class MyClass {
   private String val1;
   private String val2;
   private Map conte         


        

Answer 1

I think the simplest way of achieve what you want is using:

ObjectMapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);

This will add type information in the serialized json.

Here you are a running example, that you will need to adapt to Spring:

public class Main {

    public enum MyEnum {
        enumValue1
    }

    public static void main(String[] args) throws IOException {
        ObjectMapper mapper = new ObjectMapper();

        MyClass obj = new MyClass();
        obj.setContext(new HashMap<String, Object>());

        obj.setVal1("foo");
        obj.setVal2("var");
        obj.getContext().put("key1", "stringValue1");
        obj.getContext().put("key2", MyEnum.enumValue1);
        obj.getContext().put("key3", 3.0);

        mapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
        String json = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(obj);

        System.out.println(json);

        MyClass readValue = mapper.readValue(json, MyClass.class);
        //Check the enum value was correctly deserialized
        Assert.assertEquals(readValue.getContext().get("key2"), MyEnum.enumValue1);
    }

}

The object will be serialized into something similar to:

[ "so_27871226.MyClass", {
  "val1" : "foo",
  "val2" : "var",
  "context" : [ "java.util.HashMap", {
    "key3" : 3.0,
    "key2" : [ "so_27871226.Main$MyEnum", "enumValue1" ],
    "key1" : "stringValue1"
  } ]
} ]

And will be deserialized back correctly, and the assertion will pass.

Bytheway there are more ways of doing this, please look at https://github.com/FasterXML/jackson-docs/wiki/JacksonPolymorphicDeserialization for more info.

I hope it will help.