GQL get ID field

Question

On google appengine, you can retrieve the hash key value by doing a query like

select __key__ from furniture

But appengine datastore maintains a nicely autoincremented field ID for each kind.

How can I access it from a query?

select ID from furniture

Doesn't work

Answer 1

I believe that a Gcl query cannot incorporate calls to accessor methods or attribute extraction (much in the same vein as the fact it can only do "SELECT * FROM" to fetch whole entities or "SELECT __key__ FROM" to fetch keys only -- it cannot pick and choose fields as in [hypothetical!-)] "SELECT this, that FROM").

So, you need to fetch the keys, then call each key's .id() accessor (if you want None for keys that don't have an ID but rather a name; use .id_or_name() if you'd rather get the name, if available, and None only as a last resort). E.g., to get non-None IDs only:

thekeys = db.GqlQuery('SELECT __key__ FROM Whatever').fetch(1000)
theids = [k.id() for k in thekeys if k.id() is not None]