From ebc89520d3f7589da35d4e7b78637fbe7d4d664a Mon Sep 17 00:00:00 2001 From: Raphaël Barrois Date: Sun, 24 May 2015 18:21:04 +0200 Subject: Add lazy loading to factory.Iterator. factory.Iterator no longers begins iteration of its argument on declaration, since this behavior may trigger database query when that argument is, for instance, a Django queryset. The ``factory.Iterator``'s argument will only be called when the containing ``Factory`` is first evaluated; this means that factories using ``factory.Iterator(models.MyThingy.objects.all())`` will no longer call the database at import time. --- factory/declarations.py | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'factory') diff --git a/factory/declarations.py b/factory/declarations.py index 8f2314a..f0dbfe5 100644 --- a/factory/declarations.py +++ b/factory/declarations.py @@ -160,12 +160,19 @@ class Iterator(OrderedDeclaration): def __init__(self, iterator, cycle=True, getter=None): super(Iterator, self).__init__() self.getter = getter + self.iterator = None if cycle: - iterator = itertools.cycle(iterator) - self.iterator = utils.ResetableIterator(iterator) + self.iterator_builder = lambda: utils.ResetableIterator(itertools.cycle(iterator)) + else: + self.iterator_builder = lambda: utils.ResetableIterator(iterator) def evaluate(self, sequence, obj, create, extra=None, containers=()): + # Begin unrolling as late as possible. + # This helps with ResetableIterator(MyModel.objects.all()) + if self.iterator is None: + self.iterator = self.iterator_builder() + logger.debug("Iterator: Fetching next value from %r", self.iterator) value = next(iter(self.iterator)) if self.getter is None: -- cgit v1.2.3