Play Framework - JSON Serialization Cyclic References (e.g. Files-User, User-Files) -- Stackoverflow

Question

I've been playing around with the play framework for a couple of days now but came across one issue I can't solve: Suppose you have some "User" and "File" classes. Both reference each other and are persisted in the database with ebean (@ManyToOne, @OneToMany). Now when return a user as JSON I get a stackoverflow Error. Is this a bug in play or am I missing something? ``` @Entity public class File extends Model { private static final long serialVersionUID = 1L; @Id @GeneratedValue public Long id; @ManyToOne(cascade=CascadeType.ALL) public User author; } ``` ``` @Entity public class User extends Model { private static final long serialVersionUID = 1L; @Id @GeneratedValue public Long id; @OneToMany(mappedBy="author", cascade=CascadeType.ALL) public List files; } ``` ``` import play.libs.Json; public class Users extends Controller { public static Result getJSON() { List users = new Model.Finder(String.class, User.class).all(); return ok(Json.toJson(users)); } } `…

Accepted Answer

Okay, after hours of googling I found the solution: There is an annotation @JsonIgnore (import it from org.codehaus.jackson.annotate.JsonIgnore) which tells the JSON method to ignore this property.

EDIT: Digging further, the cleaner solution for dealing with cyclic references during JSON Serialization is to write a custom De- and Serializer. A very good post by Steve Hill can be found here: http://dev.sghill.net/2012/04/how-do-i-write-jackson-json-serializer.html

Play Framework - JSON Serialization Cyclic References (e.g. Files->User, User->Files) --> Stackoverflow

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