#33023: InMemoryUploadedFile - opening with context manager multiple time is
throwing error
--------------------------------+--------------------------------------
Reporter: Harsh Bhikadia | Owner: nobody
Type: Bug | Status: closed
Component: Core (Other) | Version: 3.2
Severity: Normal | Resolution: fixed
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Changes (by Harsh Bhikadia):
* status: new => closed
* resolution: => fixed
Old description:
> **What is the issue:**
> when "opening" the "uploaded file" with "context manager (like `with
> file.open('rb') as f:`) multiple times it is throwing `` exception
>
> **Explaination**
> Digging into the code, I realised that `InMemoryUploadedFile` overrides
> the `open` method from `File` instance - the implementation just "seeks
> to 0". Since the context manager will call the `close` method on "exit".
> When "opening" the file again (with or without context manager) it fails
> with "cannot seek(0) of already closed file"
>
> ** Potential solution**
> - Not sure why the "open" method was overridden - if not required then
> just should remove the "overridden method"
> - or making sure the file is "re-opened" (like in `File`) if closed
>
> **To conclude**
>
> Since
> [https://docs.djangoproject.com/en/3.2/ref/files/file/#django.core.files.File.open
> the doc on `File`] mentions that it could be used with "context manager"
> - I think this is unexpected behaviour and should be fixed.
>
> I have been using Django for many years but new to contribution/issue
> reporting, so forgive me when I am being ignorant.
>
> I am interested in fixing this myself if someone here gives me a green
> signal for it.
New description:
**What is the issue:**
when "opening" the "uploaded file" with "context manager (like `with
file.open('rb') as f:`) multiple times it is throwing `ValueError: I/O
operation on closed file.` exception
**Explaination**
Digging into the code, I realised that `InMemoryUploadedFile` overrides
the `open` method from `File` instance - the implementation just "seeks to
0". Since the context manager will call the `close` method on "exit". When
"opening" the file again (with or without context manager) it fails with
"cannot seek(0) of already closed file"
** Potential solution**
- Not sure why the "open" method was overridden - if not required then
just should remove the "overridden method"
- or making sure the file is "re-opened" (like in `File`) if closed
**To conclude**
Since
[https://docs.djangoproject.com/en/3.2/ref/files/file/#django.core.files.File.open
the doc on `File`] mentions that it could be used with "context manager"
- I think this is unexpected behaviour and should be fixed.
I have been using Django for many years but new to contribution/issue
reporting, so forgive me when I am being ignorant.
I am interested in fixing this myself if someone here gives me a green
signal for it.
--
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Ticket URL: <https://code.djangoproject.com/ticket/33023#comment:1>
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