Entites can be retrieved by key, but the key slot is nil about appengine-magic HOT 1 CLOSED

This is expected behavior, although perhaps it could use better documentation. When you specify a nil primary key for an entity, appengine-magic assumes you want to use automatically generated primary keys. These keys are not stored as user-accessible entity slots. To access them, you need to use the get-key-object function. Your call to retrieve works because retrieve explicitly operates on primary keys, but, as you noted, the :id slot is not populated. The ^:key metadata marker is really just there for cases when you want to specify your own primary keys.

Your example is more idiomatic if you omit the :id field altogether: (defentity Foo [name]). Incidentally, the production App Engine will not start numbering your objects at 1, and the automatic primary keys will probably not have monotonically increasing numbers.

from appengine-magic.