Spring mvc @RequestBody how to parse JPA Entity with @EmbeddedId

insci :

I have 2 Entities: User and UserAlias. User have composite PK. I have some questions:

1. How to parse JSON in spring MVC controller to populate User and UserPK objects, for example with this data:

   { "id" : 1, "name" : "newUser", "aliases": [ "alias1", "alias2", "alias3" ] }

If i writepublic void createUser(@RequestBody User user) i will obviously get an exception.
How can i write my controller method to parse data to both entities?

2. For now i'm using a DTO object to parse JSON with @RequestBody and populate models. But i'm not sure this is good way to do this task.

User.java

@Entity
@Table(name = "user")
public class User {

    @EmbeddedId
    private UserPK userid;

    public User(){}
    public User(UserPK userid) {
        this.userid = userid;
        this.aliases = aliases;
    }

    @OneToMany(
            mappedBy = "user",
            cascade = CascadeType.ALL,
            orphanRemoval = true
    )
    public List<UserAlias> aliases = new ArrayList<>();
    }

UserPK.java

@Embeddable
public class UserPK implements Serializable {

    @NotNull
    @Column(name = "id")
    private Integer id;

    @NotNull
    @Column(name = "name")
    private String name;

    public UserPK(){};

    public UserPK(Integer id, String name){
        this.id = id;
        this.name = name;
    }

}

UserAlias.java

@Entity
@Table(name = "user_alias")
public class UserAlias {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id")
    private Integer id;

    @Column(name = "user_alias")
    private String userAlias;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumns({
            @JoinColumn(
                    referencedColumnName = "id"),
            @JoinColumn(
                    referencedColumnName = "name")
    })
    @JsonIgnore
    public User user;

    public UserAlias(){}
    public UserAlias(String userAlias) {
        this.userAlias = userAlias;
    }

cнŝdk :

1. First question:

How to parse JSON in spring MVC controller to populate User and UserPK objects?

Well your JSON have to be matching your entity structure, so you need to have a UserId object, inside your User object in order to match the expected structure. In your case the JSON you are sharing won't match that, and will throw an Exception when passed to the Spring Controller.

This is what you will need as JSON:

{ "userid": {"id" : 1, "name" : "newUser"}, "aliases": [ "alias1", "alias2", "alias3" ] }

2. Second question:

For now i'm using a DTO object to parse JSON with @RequestBody and populate models. But i'm not sure this is good way to do this task?

Yes it's a good way to use DTO especially if you won't to keep the same JSON structure you are using right now, and using the passed DTO you can construct your User object respectively.

Using @JsonUnwrapped annotation:

If you want to avoid the use of a DTO, you can just use Jackson's @JsonUnwrapped annotation, with your userId field, this way its properties will be serialized as properties of the User class and your first JSON will be accepted.