In django, which format does models.ImageField take by default

Question

I wanted to upload files with limited extension on imagefield. So, how can I validate my image field for jpg,bmp and gif only. Also, which extension does image field take in by default?

Answer 1

This is how I do it:

from django.utils.image import Image

# settings.py
# ALLOWED_UPLOAD_IMAGES = ('gif', 'bmp', 'jpeg')


class ImageForm(forms.Form):

    image = forms.ImageField()

    def clean_image(self):
        image = self.cleaned_data["image"]
        # This won't raise an exception since it was validated by ImageField.
        im = Image.open(image)

        if im.format.lower() not in settings.ALLOWED_UPLOAD_IMAGES:
            raise forms.ValidationError(_("Unsupported file format. Supported formats are %s."
                                          % ", ".join(settings.ALLOWED_UPLOAD_IMAGES)))

        image.seek(0)
        return image

Works for ModelForm as well.

Unit test:

from StringIO import StringIO

from django.core.files.uploadedfile import SimpleUploadedFile
from django.test.utils import override_settings
from django.test import TestCase


class ImageFormTest(TestCase):

    def test_image_upload(self):
        """
        Image upload
        """
        content = 'GIF87a\x01\x00\x01\x00\x80\x01\x00\x00\x00\x00ccc,\x00' \
                  '\x00\x00\x00\x01\x00\x01\x00\x00\x02\x02D\x01\x00;'
        image = StringIO(content)
        image.name = 'image.gif'
        image.content_type = 'image/gif'
        files = {'image': SimpleUploadedFile(image.name, image.read()), }

        form = ImageForm(data={}, files=files)
        self.assertTrue(form.is_valid())


    @override_settings(ALLOWED_UPLOAD_IMAGES=['png', ])
    def test_image_upload_not_allowed_format(self):
        image = StringIO('GIF87a\x01\x00\x01\x00\x80\x01\x00\x00\x00\x00ccc,\x00'
                         '\x00\x00\x00\x01\x00\x01\x00\x00\x02\x02D\x01\x00;')
        image.name = 'image'
        files = {'image': SimpleUploadedFile(image.name, image.read()), }
        form = ImageForm(data={}, files=files)
        self.assertFalse(form.is_valid())

Pillow will allow a bunch of image formats