+class SortedMultiQuerySet(MultiQuerySet):
+ def __init__(self, *args, **kwargs):
+ self.order_by = kwargs.pop('order_by', None)
+ self.sortfn = kwargs.pop('sortfn', None)
+ if self.order_by is not None:
+ self.sortfn = lambda a, b: cmp(getattr(a, self.order_by),
+ getattr(b, self.order_by))
+ super(SortedMultiQuerySet, self).__init__(*args, **kwargs)
+
+ def __getitem__(self, item):
+ sort_heads = [0] * len(self.querysets)
+ try:
+ indices = (offset, stop, step) = item.indices(self.count())
+ except AttributeError:
+ # it's not a slice - make it one
+ return self[item : item + 1][0]
+ items = []
+ total_len = stop - offset
+ skipped = 0
+ i_s = range(len(sort_heads))
+
+ while len(items) < total_len:
+ candidate = None
+ candidate_i = None
+ for i in i_s:
+ def get_next():
+ return self.querysets[i][sort_heads[i]]
+ try:
+ if candidate is None:
+ candidate = get_next()
+ candidate_i = i
+ else:
+ competitor = get_next()
+ if self.sortfn(candidate, competitor) > 0:
+ candidate = competitor
+ candidate_i = i
+ except IndexError:
+ continue # continue next sort_head
+ # we have no more elements:
+ if candidate is None:
+ break
+ sort_heads[candidate_i] += 1
+ if skipped < offset:
+ skipped += 1
+ continue # continue next item
+ items.append(candidate)
+
+ return items
+