Hi,
I am reading the docs for Key generation in app engine. I'm not sure what effect using a simple String key has over a real Key. For example, when my users sign up, they must supply a unique username:
class User {
/** Key type = unencoded string. */
@PrimaryKey
private String name;
}
now if I understand the docs correctly, I should still be able to generate named keys and entity groups using this, right?:
// Find an instance of this entity:
User user = pm.findObjectById(User.class, "myusername");
// Create a new obj and put it in same entity group:
Key key = new KeyFactory.Builder(
User.class.getSimpleName(), "myusername")
.addChild(Goat.class.getSimpleName(), "baa").getKey();
Goat goat = new Goat();
goat.setKey(key);
pm.makePersistent(goat);
the Goat instance should now be in the same entity group as that User, right? I mean there's no problem with leaving the User's primary key as just the raw String?
Is there a performance benefit to using a Key though? Should I update to:
class User {
/** Key type = unencoded string. */
@PrimaryKey
private Key key;
}
// Generate like:
Key key = KeyFactory.createKey(
User.class.getSimpleName(),
"myusername");
user.setKey(key);
it's almost the same thing, I'd still just be generating the Key using the unique username anyway,
Thanks
