[FIXED] How do I make fields in DTO optional using lombok?

Issue

So I have a DTO like this,

@NoArgsConstructor
@AllArgsConstructor
@Getter
@Setter
@Builder
@ToString
@JsonIgnoreProperties(ignoreUnknown=true)
public class PersonDTO {
  private String name;
  private String address;
  private String phone;
  private String other;
}

I am passing the following payload to an external API

{
    "name": "John",
    "phone": "123",
    "address": "abc"
}

This is throwing me 500 internal error:

HttpClientErrorException$NotFound: 404: "{<EOL> "status": "Error", <EOL> "message": "Error validating JSON. Error: - Invalid type Null, expected String."}"

If I comment out other property in DTO then I will successfully get 200 response. I thought @JsonIgnoreProperties annotation is supposed to ignore the properties that are not present but it seems that's not working.

Solution

The error says that they can't parse Null into String. That's very interesting error and fooled me first. Your json object with other field null probably looks like this:

{
    "name": "John",
    "phone": "123",
    "address": "abc"
}

So somehow this API can't just wrap quotes around null and tells you it's not able to parse this.

Therefore I guess you need to set the value of other to an empty string:

@NoArgsConstructor
@AllArgsConstructor
@Getter
@Setter
@Builder
@ToString
@JsonIgnoreProperties(ignoreUnknown=true)
public class PersonDTO {
  private String name;
  private String address;
  private String phone;
  private String other = ""; //empty because external api can't handle null
}

Answered By - Ausgefuchster
Answer Checked By - Clifford M. (JavaFixing Volunteer)