Getting AssertionError while using ObjectifyService.register - google-app-engine

Question

I am in the middle of trying to refactor some of my data models, but I've run into a problem that I don't understand.
Originally I had a simple data model comprised of 3 entity classes, which looked something like this:
#Entity
public final class Teacher {
#Id
private Long id;
private String primarySubject;
public Teacher() {}
public Teacher(String primarySubject) {
this.primarySubject = primarySubject;
}
//getters & setters
}
#Entity
public final class Student {
#Id
private String username;
#Load
#Index
private Ref<Teacher> homeRoomTeacher;
public Student() {}
public Student(String username, Teacher teacher) {
this.username = username;
homeRoomTeacher = Ref.create(teacher);
}
//getters & setters
}
#Entity
public final class School {
#Id
private String name;
#Load
private Set<Ref<Teacher>> teachers;
#Load
private Set<Ref<Student>> students;
public School() {}
public School(String name) {
this.name = name;
}
//getters & setters
}
And this all worked fine.
But we decided that it would be more useful for us to embed the entities directly instead of Refs...
#Entity
#Embed
public final class Teacher {
#Id
private Long id;
private String primarySubject;
public Teacher() {}
public Teacher(String primarySubject) {
this.primarySubject = primarySubject;
}
//getters & setters
}
#Entity
#Embed
public final class Student {
#Id
private String username;
#Index
private Ref<Teacher> homeRoomTeacher;
public Student() {}
public Student(String username, Teacher teacher) {
this.username = username;
homeRoomTeacher = Ref.create(teacher);
}
//getters & setters
}
#Entity
public final class School {
#Id
private String name;
private Set<Teacher> teachers;
private Set<Student> students;
public School() {}
public School(String name) {
this.name = name;
}
//getters & setters
}
After making those changes, then all of our junit tests started to fail with an AssertionError during registration of the School class in our test setup methods which look like:
#Before
public void setUp() throws Exception {
helper = new LocalServiceTestHelper(new LocalDatastoreServiceTestConfig());
helper.setUp();
ObjectifyService.register(Teacher.class);
ObjectifyService.register(Student.class);
ObjectifyService.register(School.class);
// more setup
}
The AssertionError doesn't appear until the line that registers the School class, and according to the stack trace is being thrown from the method "com.googlecode.objectify.impl.translate.CreateContext.enterCollection" but I'm not certain how to go about fixing it.
Does anyone have any ideas?

Answer 1

I suspect the error you are getting is to do with the fact that you are trying to register a class which you have annotated with #Embed.
The objectify documentation clearly states that #Embed classes do not have to be registered - maybe this is the cause of the issue.
Also, I'm not 100% sure on this but I don't think you need #Id on an embedded class.
I would suggest you give the following changes a go:
#Embed
public final class Teacher {
#Id
private Long id;
private String primarySubject;
public Teacher() {}
public Teacher(String primarySubject) {
this.primarySubject = primarySubject;
}
//getters & setters
}
#Embed
public final class Student {
#Id
private String username;
#Index
private Ref<Teacher> homeRoomTeacher;
public Student() {}
public Student(String username, Teacher teacher) {
this.username = username;
homeRoomTeacher = Ref.create(teacher);
}
//getters & setters
}
#Before
public void setUp() throws Exception
{
helper = new LocalServiceTestHelper(new LocalDatastoreServiceTestConfig());
helper.setUp();
ObjectifyService.register(School.class);
// more setup
}
Hope this helps!