What is the best way to get multiple objects using a List of Keys on Google App Engine (Java)?

Question

I have a many-to-many relationship. Just like in the example from the documentation:

Person.java
    private Set<Key> favoriteFoods;

Food.java
    private Set<Key> foodFans;

How do I get all "favorite foods" of a certain "food fan", if i have retrieved a "Person" object and i have the favoriteFoods key set. Is there a better way than:

for (Key k: favoriteFoods)
{ foodObjectsCollection.add( pm.getObjectById(Food.class, k) ); }

What's the cheapest and most efficient option here? I usually have to generate tables with object data in my app.

Answer 1

It seems like you need JDOQL. For this concrete task try:

Query query = pm.newQuery(Food.class, ":p.contains(key)");
query.execute(favoriteFoods);

contains() behaves just like IN statement in SQL, so this query will fetch all Food objects from specified key set.