title: How to generate presigned S3 urls using django-storages?
body: <p>I have a Django form which saves a file to s3 through the django-storages library and works fine. How can I generate and return a pre-signed url so the user can access the file temporarily after it is uploaded ? Is this abstracted by django-storages or do I have to use the boto3 api?</p>
  <p>I have spent hours going through the Django-storages documentation however it is not very clear how to do this ..</p>
  <p>form.py</p>
  <pre><code>class DocumentForm(forms.Form):
      docfile = forms.FileField(
          label='Select a file',
          help_text='max. 42 megabytes'
      )
     name = models.CharField(max_length=20)
     uploaded_at = models.DateTimeField(auto_now_add=True)
  </code></pre>
  <p>views.py</p>
  <pre><code>def upload_file(request):
     if request.method == 'POST:
        form = DocumentForm(request.POST)
        if form.is_valid():
           form.save()
           url = #generate pre-signed url of uploaded file here
           return render(request, 'upload_response.html', url)
  
  </code></pre>