Jackson deserialize extra fields as map

Question

I\'m looking to deserialize any unknown fields in a JSON object as entries in a map which is a member of a pojo.

For example the json

{
  \"knownFiel         


        

Answer 1

There is a feature and an annotation exactly fitting this purpose.

I tested and it works with UUIDs like in your example:

class MyUUIDClass {
    public int knownField;

    Map<String, UUID> unknownFields = new HashMap<>();

    // Capture all other fields that Jackson do not match other members
    @JsonAnyGetter
    public Map<String, UUID> otherFields() {
        return unknownFields;
    }

    @JsonAnySetter
    public void setOtherField(String name, UUID value) {
        unknownFields.put(name, value);
    }
}

And it would work like this:

    MyUUIDClass deserialized = objectMapper.readValue("{" +
            "\"knownField\": 1," +
            "\"foo\": \"9cfc64e0-9fed-492e-a7a1-ed2350debd95\"" +
            "}", MyUUIDClass.class);

Also more common types like Strings work:

class MyClass {
    public int knownField;

    Map<String, String> unknownFields = new HashMap<>();

    // Capture all other fields that Jackson do not match other members
    @JsonAnyGetter
    public Map<String, String> otherFields() {
        return unknownFields;
    }

    @JsonAnySetter
    public void setOtherField(String name, String value) {
        unknownFields.put(name, value);
    }
}

(I found this feature in this blog post first).