#29510: QueryDict.copy() returns closed files when the type of file is
TemporaryUploadedFile
-------------------------------------+-------------------------------------
Reporter: Liquid Scorpio | Owner: Dan
| Madere
Type: Bug | Status: assigned
Component: File | Version: 1.11
uploads/storage |
Severity: Normal | Resolution:
Keywords: QueryDict, upload, | Triage Stage: Accepted
file |
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by Dan Madere):
Replying to [comment:10 Paulo]:
> Replying to [comment:9 Claude Paroz]:
> > Did you explore possible handling of such file objects in
`QueryDict.__deepcopy__`?
>
> To keep the file on copy?
> If so then yes, we can check value for UploadedFile and create a new
instance that points to the same underlying file (although I guess that's
more shallow than deep copy).
> To have fully deep copy we'd have to create new tmp if is on disk or
somehow copy the file stream.
After trying it, I don't think either of these suggestions is workable,
considering the nature of `TemporaryUploadedFile`. It has logic where the
file is deleted as soon as it's closed. When copying/streaming the old
file's content to the new one, we have a problem where the new file
deletes itself immediately.
I stepped back, and pondered why are people copying a `QueryDict` anyway,
and what do they expect to happen to a `TemporaryUploadedFile` inside?
[[https://docs.djangoproject.com/en/dev/ref/request-response/#querydict-
objects]]:
{{{
class QueryDict¶
In an HttpRequest object, the GET and POST attributes are instances of
django.http.QueryDict, a dictionary-like class customized to deal with
multiple values for the same key. This is necessary because some HTML form
elements, notably <select multiple>, pass multiple values for the same
key.
The QueryDicts at request.POST and request.GET will be immutable when
accessed in a normal request/response cycle. To get a mutable version you
need to use QueryDict.copy().
}}}
That leads me to think that people are copying a `QueryDict` because it's
a nice starting point to have all the query params organized, but they
want to modify it, and pass to the template. Doing so would result in a
`This QueryDict instance is immutable` exception, and the advice above, so
they try to copy the `QueryDict` before modifying it.
I propose we omit `TemporaryUploadedFile` values on deep copy of a
`QueryDict`, and will open a PR for feedback.
--
Ticket URL: <https://code.djangoproject.com/ticket/29510#comment:12>
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