Objectify One-to-Many and Many-To-One in Google App Engine - google-app-engine

Question

I'm creating simple backend on Google App Engine using Objectify, that can store Users and thier Recipes.
Model look like this:
User has many Recipes, every Recipe has one author.
I want to be able to:
Get list of Recipes with authors in it
Get list of Users without fetching all recipes
Get one User with all his recipes
According to guide I have done this:
#Entity
public class User {
#Id
private Long id;
#Index
private String name;
List<Recipe> recipes = new ArrayList<>();
/* Other fields */
}
and Recipe :
#Entity
public class Recipe {
#Id
Long id;
String name;
#Index
#Load
Ref<User> author;
/* Other fields */
}
I save Recipe with author (User object) in it.
and 2. requirements work fine,
but when I try to get User with all recipes like this:
public User get(#Named("id") long id) throws NotFoundException {
User user = ofy().load().type(User.class).id(id).now();
if (user == null) {
throw new NotFoundException("Could not find User with ID: " + id);
} else {
List<Recipe> recipes = ofy().load().type(Recipe.class).filter("author", user).list();
account.recipes = recipes;
}
return account;
}
I get empty recipe list.
What am I doing wrong ?

Answer 1

Your author property in your Recipe is a Ref, which is essentially a Key, so you need to filter on that key, like this:
List<Recipe> recipes = ofy().load().type(Recipe.class).filter("author =", Key.create(user)).list();
Incidentally, instead of using .now(), checking for null, then throwing an exception, you could use .safe() which does the same thing for you.