Django How to save an image from url in model form?

Question

I have a modelform that looks like this:

class NewSongForm(forms.ModelForm):
    image_url = forms.URLField(required=False)

    def save(self, *args, **kwargs):
        url = self.cleaned_data['image_url']
        if not self.cleaned_data['image'] and url:
            # no file was uploaded, but a url was given
            # fetch the image from the url and use that.
            img_temp = NamedTemporaryFile(delete=True)
            img_temp.write(urllib2.urlopen(url).read())
            img_temp.flush()
            self.cleaned_data['image'] = File(img_temp)

        return super(NewSongForm, self).save(*args, **kwargs)

    class Meta:
        model = Song
        fields = ('image', )  # is an ImageField

Basically a user can upload either an image from the image field (A ImageField), or they can supply a url through the image_url field, (which is a URLField)

This code looks like it should work, but it doesn't. I got the specific method for saving the url to File via urllib2 from this stack overflow answer: Django: add image in an ImageField from image url

Answer 1

Solved my own problem. I needed to place the download code into the clean method instead of the save method.

class NewSongForm(forms.ModelForm):
    image_url = forms.URLField(required=False)

    def clean(self, *args, **kwargs):
        all_data = self.cleaned_data
        url = all_data['image_url']
        image = all_data['image']

        if not image and url:
            img_temp = NamedTemporaryFile(delete=True)
            img_temp.write(urllib2.urlopen(url).read())
            img_temp.flush()
            all_data['image'] = File(img_temp)

        return all_data

    class Meta:
        model = Song
        fields = ('image', )  # is an ImageField