30 

    31 

    32 def dateFetch(queryGen, last=None, batchSize=100):

    33   """Iterator that yields an entity in batches.

    34 

    35   Args:

    36     queryGen: should return a Query object

    37     last: used to .filter() for last_modified_on

    38     batchSize: how many entities to retrieve in one datastore call

    39 

    40   Retrieved from http://tinyurl.com/d887ll (AppEngine cookbook).

    41   """

    42 

    43   from google.appengine.ext import db

    44 

    45    # AppEngine will not fetch more than 1000 results

    46   batchSize = min(batchSize,1000)

    47 

    48   query = None

    49   done = False

    50   count = 0

    51 

    52   while not done:

    53     print count

    54     query = queryGen()

    55     query.order('last_modified_on')

    56     if last:

    57       query.filter("last_modified_on > ", last)

    58     results = query.fetch(batchSize)

    59     for result in results:

    60       count += 1

    61       yield result

    62     if batchSize > len(results):

    63       done = True

    64     else:

    65       last = results[-1].last_modified_on