How does one get a count of rows in a Datastore model in Google App Engine?

Question

I need to get a count of records for a particular model on App Engine. How does one do it?

I bulk uploaded more than 4000 records but modelname.count() only shows me

Answer 1

I still hit the 1000 limit with count so adapted dar's code (mine's a bit quick and dirty):

class GetCount(webapp.RequestHandler):
    def get(self):
        query = modelname.all(keys_only=True)

        i = 0
        while True:
            result = query.fetch(1000)
            i = i + len(result)
            if len(result) < 1000:
                break
            cursor = query.cursor()
            query.with_cursor(cursor)

        self.response.out.write('
Count: '+str(i)+'
')