[FIXED] How to set boolean to null instead of false, if not specified in REST query

Issue

I have a Spring Boot REST API and one of the endpoints takes requests that include a body, like this:

@GetMapping("/search")
public List<ItemDto> searchDevice(@RequestBody ItemDto itemDto){
    // code
}

The DTO looks like this:

@JsonInclude(JsonInclude.Include.NON_NULL)
public class ItemDto {

//other fields

@JsonProperty(value = "status")
private boolean status;

// getters and setters
}

So my problem is this: when I send a request not containing status it defaults to false, which is not the behaviour I need. I want status to be null, when it is not specified. How can I achieve this?

Another interesting behaviour is that status is false even when I specify it in the query as "status": null

As you can see, I already tried to use the annotations @JsonInclude and @JsonProperty, that I've seen recommended in similiar questions, but they are not working for me. The boolean still defaults to false. Is there any other fix for this?

Solution

boolean is a primitive type which means it is not a Java object. As such it cannot be null, just true or false. You can just replace it by the Java object equivalent which is Boolean and then it will be able to be null. In Java there is boxing an unboxing which allow seamless conversion between primitive type and Java object equivalent (or wrapper) when needed, so you can still do if(yourBoolean) if it's a Boolean but be aware that this can throw NPE if yourBoolean is null.

Note that it is not usually good practice to do that, you shouldn't have a different logic when the boolean isn't here as when it's null, as it is not really a boolean anymore. If you have control over the input and you really have 3 states, then look into using an enum as it might be a better choice (or you can use 2 boolean).

Answered By - Nyamiou The Galeanthrope
Answer Checked By - Timothy Miller (JavaFixing Admin)