Django 使用 Boto3 将表单上传到 AWS S3 会导致空文件

Question

I am having a multipart/form-data form that should upload to a S3 bucket, using Boto3.

All is happening as expected, but at the end, the file at the S3 bucket has 0 bytes.

forms.py:

class DropOffFilesForm(forms.ModelForm):
    file = forms.FileField(error_messages={'invalid_type': _("Please upload only PDF, JPG, PNG, XLS(x), DOC(x) files")},
                       validators=[
                           FileTypeValidator(allowed_types=['application/pdf', 'image/*', 'application/msword', 'application/vnd.openxmlformats-officedocument.wordprocessingml.document', 'application/vnd.ms-excel', 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'], allowed_extensions=['.pdf', '.png', '.jpg', '.doc', '.docx', '.xls', '.xlsx'])], required=False)
    description = forms.CharField(widget=forms.Textarea, label=_("Description"), required=False)

    def clean_description(self):
        data = self.cleaned_data['description']
        return data

    class Meta:
        model = DropOffFiles
        exclude = ['filename',]
        fields = ['file', 'description']

views.py:

file_form = DropOffFilesForm(request.POST, request.FILES)

if file_form.is_valid():

   file_form = file_form.save(commit=False)

   s3 = boto3.client('s3', region_name=settings.AWS_ZONE,
                           aws_access_key_id=settings.AWS_KEY,
                           aws_secret_access_key=settings.AWS_SECRET)

   file = request.FILES['file']

   if file:

        file_type = file.content_type
        extension = file.name.split(".")[-1]

        # construct file name and location
        filename = calculate_md5(file) + '.'+extension

        # save the file
        try:
             response = s3.upload_fileobj(file, 'bucketname', filename)
        except ClientError as e:
             logging.error(e)
             return False



        file_form.filename = filename
        file_form.dropoff = dropoff
        file_form.save()

Happy for any suggestion.

Answer 1

calculate_md5 does a read() on the InMemoryFile, which sets the cursor to the end of the file.

The right way is to reset the cursor using

file.file.seek(0)

and then recall it. This will set the cursor to the beginning and the content of the file is available.