CODEWITHSUNDEEP
javaspring-bootspring-mvc
Fran Moya
Fran Moya

Reputation: 89

Why @RequestBody works without setters?

I am writing a controller with the annotation @RequestBody in order to map to a Java object. The method that uses the annotation is:

@PostMapping("/users")
public ResponseEntity<Object> createUserForProject(@Valid @RequestBody User user) {
        log.info("Creating a user " + user.getEmail());
}

This is the User class:

@Getter
@AllArgsConstructor
@Slf4j
@EqualsAndHashCode
@ToString
public class User {
    @NotEmpty
    @Email
    private String email;

    @NotEmpty
    private String firstName;

    @NotEmpty
    private String lastName;

    @JsonIgnore
    private Optional<LocalDate> lastLogonDate = Optional.empty();

    @JsonIgnore
    private Optional<LocalDate> lastModificationDate = Optional.empty();

    @JsonIgnore
    private Optional<LocalDate> creationDate = Optional.empty();

    @JsonIgnore
    private Optional<LocalDate> mfaWarningDate = Optional.empty();

    @JsonIgnore
    private Optional<LocalDate> auditStartNotificationDate = Optional.empty();

    @JsonIgnore
    private boolean enabled = true;

    public User() {
        log.info("HI");
    }

    (More code without explicit setters)

So when I make a POST call with the body

{
   "email":"[email protected]",
   "firstName":"testName",
   "lastName":"testLastName"
}

Outputs HI and the log with the Creating a user [email protected] message, so the object is created. My point here is... why does this really work? The HttpMessageConverter is calling the no-args constructor and there are no setters to call after create the object with the constructor. How do the object attributes get their values without any setter? What am I missing here?

Upvotes: 2

Views: 2683

Answers (1)

Igor Flakiewicz
Igor Flakiewicz

Reputation: 793

Spring boot uses Jackson for Object <-> JSON conversion, and Jackson does not need setters, it sets fields via reflection.

Here is a relevant question about Jackson and why it doesn't need setters How does jackson set private properties without setters?

Upvotes: 3

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