File Upload Issue

[Bo Shi]

Hi All,

I've been playing with FileField and file uploading.

I do have a problem that I can't seem to solve; when a file gets
uploaded, it is placed in the media directory under some random
filename the client was using. I would like to normalize this filename
so that

foo.txt

is saved on the server as

MEDIA_ROOT/text/username_fileid.txt

I have tried combining _post_save() and os.rename(...) to some limited
success but am not able to reset my FileField to the new file path (my
assumption is that using save() inside _post_save() causes infinite
recursion, no?). Clearly said strategy is an ugly hack with some major
problems.

Is there an elegant way to do this?

Regards,
Bo

[Luke Plant]

> I have tried combining _post_save() and os.rename(...) to some limited
> success but am not able to reset my FileField to the new file path (my
> assumption is that using save() inside _post_save() causes infinite
> recursion, no?). Clearly said strategy is an ugly hack with some
> major problems.
>
> Is there an elegant way to do this?

Could you not simply check in the _post_save() method whether the file
already has a correct filename, and if so do nothing, otherwise move it
and save the object? That would avoid any infinite recursion.

Luke

--
"God demonstrates his love towards us in this, that while we were still
sinners, Christ died for us." (Romans 5:8)

Luke Plant || L.Plant.98 (at) cantab.net || http://lukeplant.me.uk/

[Nebojša Đorđević - nesh]

On 15-10-2005, at 9:57, Bo Shi wrote:

> I have tried combining _post_save() and os.rename(...) to some limited
> success but am not able to reset my FileField to the new file path (my
> assumption is that using save() inside _post_save() causes infinite
> recursion, no?). Clearly said strategy is an ugly hack with some
> major
> problems.

IMO you don't save() in _pre_save(). This function is called *before*
record is saved so any modification are automatically saved.

I'm using something like this (you can ignore quoting stuff):
...
def _pre_save(self):
from utils.utils import store_file
self.image = rename_by_field(self.image, self.slug)
self.logo_image = rename_by_field(self.logo_image, self.slug)
#

def rename(old_name, new_name):
""" rename image old_name -> new_name """
try:
shutil.move(old_name, new_name)
return new_name
except IOError:
return old_name
# rename

_HEX_SUB = re.compile(r'\%([0-9A-F]{2})')
def rename_by_field(file_path, req_name):
if file_path.strip() == '': return '' # no file uploaded

old_name = os.path.basename(file_path)
path = os.path.dirname(file_path)

name, ext = os.path.splitext(old_name)

# make new name, all filenames are LOWERCASED, unsafe characters
are encoded as [<HEX>]
# I don't like %xx url type of quoting ;)
new_name = urllib.quote(req_name.lower(), safe='')
new_name = _HEX_SUB.sub(r'[\1]', new_name) + ext

dest_path = os.path.join(path, new_name)

if new_name != old_name:
return rename(file_path, dest_path)
else:
return file_path
#
#


---
Nebojša Đorđević - nesh
Studio Quattro - Niš - SCG

http://djnesh.blogspot.com/ | http://djnesh-django.blogspot.com/
Registered Linux User 282159 [http://counter.li.org]

[Bo Shi]

Hey Nesh,

Moving the rename logic to _pre_save() would be the best way of doing
things but I have a problem where I rename the uploaded file into one
based on it's primary key. While in _pre_save(), self.id is None, so
is there a way to access the value that will become the primary key?

Bo

[Nebojša Đorđević - nesh]

Well, I never (yet) run in this kind of a problem. Generally I always
use some kind of SlugField as a secondary primary key (unique) that
gives me a pretty (and human readable) URLs. It's not possible to
know under witch id record will be saved.

You can try to move rename logic into _post_save(). IIRC when you hit
_post_save object is already in db so self.id will have a value.
After renaming file and updating image field you must again save()
object.