Resizing uploaded files in django using PIL

Question

I am using PIL to resize an uploaded file using this method:

def resize_uploaded_image(buf):
  imagefile = StringIO.StringIO(buf.read())
  imageImage = Image.open(imagefile)

  (width, height) = imageImage.size
  (width, height) = scale_dimensions(width, height, longest_side=240)

  resizedImage = imageImage.resize((width, height))
return resizedImage

I then use this method to get the resizedImage in my main view method:

image = request.FILES['avatar']
resizedImage = resize_uploaded_image(image)
content = django.core.files.File(resizedImage)
acc = Account.objects.get(account=request.user)
acc.avatar.save(image.name, content)

However, this gives me the 'read' error.

Trace:

Exception Type: AttributeError at /myapp/editAvatar Exception Value: read

Any idea how to fix this? I have been at it for hours! Thanks!

Nikunj

Answer 1

Here's how you can take a file-like object, manipulate it as an image in PIL, then turn it back into a file-like object:

def resize_uploaded_image(buf):
    image = Image.open(buf)

    (width, height) = image.size
    (width, height) = scale_dimensions(width, height, longest_side=240)

    resizedImage = image.resize((width, height))

    # Turn back into file-like object
    resizedImageFile = StringIO.StringIO()
    resizedImage.save(resizedImageFile , 'PNG', optimize = True)
    resizedImageFile.seek(0)    # So that the next read starts at the beginning

    return resizedImageFile

Note that there's already a handy thumbnail() method for PIL images. This is a variant of the thumbnail code I use in my own project:

def resize_uploaded_image(buf):
    from cStringIO import StringIO
    import Image

    image = Image.open(buf)

    maxSize = (240, 240)
    resizedImage = image.thumbnail(maxSize, Image.ANTIALIAS)

    # Turn back into file-like object
    resizedImageFile = StringIO()
    resizedImage.save(resizedImageFile , 'PNG', optimize = True)
    resizedImageFile.seek(0)    # So that the next read starts at the beginning

    return resizedImageFile