How can I deserialize a JSON to a Java class which has known mandatory fields, but can have several unknown fields?

LordSerius :

I have an input JSON which has fields what I sure inside. But, I need a flexibility to add several extra fields. I don't know the name of the extra fields, but I have to handle it.

I was thinking adding a MaP field which contains all of extra fields, but the inputs are not mapped into this field.

I want to deserialize the JSON in a Dropwizard endpoint.

Is there a way to do with Jackson?

Example:

JSON payload 1:

{
  "first_name": "John",
  "last_name": "Doe",
  "date_of_birth": "01/01/1990",
  "postcode": "1234"
}

JSON payload 2:

{
  "first_name": "Alice",
  "last_name": "Havee",
  "phone_no": 012345678,
  "passport_no": "AB 123456"
}

Later on JSON payload 3 can have even different fields.

Java DTO:

public class PersonDTO {

    // mandatory field
    private String firstName;

    // mandatory field
    private String lastName;

    // Unknown optional fields?

    // No args constructor
    // Getters
    // Setters
}

Michał Ziober :

You can use JsonAnySetter annotation:

class PersonDTO {

    @JsonProperty("first_name")
    private String firstName;

    @JsonProperty("last_name")
    private String lastName;

    private Map<String, String> extras = new HashMap<>();

    @JsonAnySetter
    public void setExtras(String name, String value) {
        this.extras.put(name, value);
    }

    // No args constructor
    // Getters
    // Setters
}

How can I deserialize a JSON to a Java class which has known mandatory fields, but can have several unknown fields?

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