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Fixed #6748 -- When printing the repr() of querysets, don't load or d…

…isplay

more than 20 objects.

This means that accidentally executing HugeStoryArchive.objects.all() at the
interactive prompt (or in the debug template) won't try to load all 4,233,010
stories into memory and print them out. That would previously cause resource
starvation and other "interesting" crashes.

If you really, really want the previous behaviour (e.g. in a doctest that
prints more than 20 items), display "list(qs)" instead of just "qs".


git-svn-id: http://code.djangoproject.com/svn/django/trunk@9202 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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commit 44f228fd61e5f45dbdfa465291319dfd5dd66393 1 parent 268ef59
Malcolm Tredinnick malcolmt authored
8 django/db/models/query.py
View
@@ -15,6 +15,9 @@
CHUNK_SIZE = 100
ITER_CHUNK_SIZE = CHUNK_SIZE
+# The maximum number of items to display in a QuerySet.__repr__
+REPR_OUTPUT_SIZE = 20
+
# Pull into this namespace for backwards compatibility.
EmptyResultSet = sql.EmptyResultSet
@@ -141,7 +144,10 @@ def __getstate__(self):
return obj_dict
def __repr__(self):
- return repr(list(self))
+ data = list(self[:REPR_OUTPUT_SIZE + 1])
+ if len(data) > REPR_OUTPUT_SIZE:
+ data[-1] = "...(remaining elements truncated)..."
+ return repr(data)
def __len__(self):
# Since __len__ is called quite frequently (for example, as part of
2  tests/regressiontests/queries/models.py
View
@@ -556,7 +556,7 @@ def __unicode__(self):
# automatically. Item normally requires a join with Note to do the default
# ordering, but that isn't needed here.
>>> qs = Item.objects.order_by('name')
->>> qs
+>>> list(qs)
[<Item: four>, <Item: one>, <Item: three>, <Item: two>]
>>> len(qs.query.tables)
1
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