Useful useful useful

fetch_all.py

def fetch_all(model_or_query):
  '''Fetch all the entities of the given model, or satisfying the given query.
  '''
  if isinstance(model_or_query, type) and issubclass(model_or_query, db.Model):
    query = model_or_query.all(keys_only=False)
  elif isinstance(model_or_query, db.Query):
    query = model_or_query
  else:
    raise Exception("model_or_query is neither a model nor a query")
  
  results = []
  while True:
    to_fetch = query.fetch(500)
    results += to_fetch
    if len(to_fetch) < 500:
      return results
    query.with_cursor(query.cursor())

Fetch all donations:

fetch_all(models.Donation.all())

Fetch all donations for school $school:

fetch_all(models.Donation.all().filter("school", school))