[2.2.x] Fixed #30252 -- Clarified need to reopen forms.fields.ImageField.image file to access raw image data.

Backport of 2282d9f2e5 from master
This commit is contained in:
Hasan Ramezani 2019-10-22 23:18:21 +02:00 committed by Mariusz Felisiak
parent f55f89f908
commit 6429d71ecb
1 changed files with 35 additions and 3 deletions

View File

@ -710,9 +710,41 @@ For each field, we describe the default widget used if you don't specify
After the field has been cleaned and validated, the ``UploadedFile``
object will have an additional ``image`` attribute containing the Pillow
`Image`_ instance used to check if the file was a valid image. Also,
``UploadedFile.content_type`` will be updated with the image's content type
if Pillow can determine it, otherwise it will be set to ``None``.
`Image`_ instance used to check if the file was a valid image. Pillow
closes the underlying file descriptor after verifying an image, so whilst
non-image data attributes, such as ``format``, ``height``, and ``width``,
are available, methods that access the underlying image data, such as
``getdata()`` or ``getpixel()``, cannot be used without reopening the file.
For example::
>>> from PIL import Image
>>> from django import forms
>>> from django.core.files.uploadedfile import SimpleUploadedFile
>>> class ImageForm(forms.Form):
... img = forms.ImageField()
>>> file_data = {'img': SimpleUploadedFile('test.png', <file data>)}
>>> form = ImageForm({}, file_data)
# Pillow closes the underlying file descriptor.
>>> form.is_valid()
True
>>> image_field = form.cleaned_data['img']
>>> image_field.image
<PIL.PngImagePlugin.PngImageFile image mode=RGBA size=191x287 at 0x7F5985045C18>
>>> image_field.image.width
191
>>> image_field.image.height
287
>>> image_field.image.format
'PNG'
>>> image_field.image.getdata()
# Raises AttributeError: 'NoneType' object has no attribute 'seek'.
>>> image = Image.open(image_field)
>>> image.getdata()
<ImagingCore object at 0x7f5984f874b0>
Additionally, ``UploadedFile.content_type`` will be updated with the
image's content type if Pillow can determine it, otherwise it will be set
to ``None``.
.. _Pillow: https://pillow.readthedocs.io/en/latest/
.. _Image: https://pillow.readthedocs.io/en/latest/reference/Image.html