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There is a form with ImageField, which returns validation error 

"Upload a valid image. The file you uploaded was either not an image or a corrupted image."

In my view I am trying to read image file content:

image = self.request.FILES.get('image')
if image:
    content = ''.join(image.chunks())

Validation error doesn't occur if I comment line with image.chunks(), also it isn't showed if I remove "django.core.files.uploadhandler.MemoryFileUploadHandler" from FILE_UPLOAD_HANDLERS setting.

So the reason could be in file object created by MemoryFileUploadHandler (InMemoryUploadedFile).

My guess was it could be that after read there is no call file.seek(0) which set file reader pointer to the begging of the file.

It could be ImageFile.to_python assumes that pointer set to the beginning. In ImageField.to_python I have added 

data.file.seek(0)

before 

file = StringIO(data.read())

and I haven't got image validation error after that.

Is it proper behavior? Or ImageField shouldn't assume that file haven't been read? Or InMemoryUploadedFile should call file.seek(0) after chunks iterator ended its work?

My django version is 1.4.3

sunprophit
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1 Answers1

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Yes, that is the intended behaviour. You should reset the file position to the beginning before validating the form:

image = self.request.FILES.get('image')
if image:
content = ''.join(image.chunks())
...
image.seek(0)
tuxcanfly
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