NotImplementedError: This backend doesn't support absolute paths.(Django)

Question

I am trying to upload my media files to AWS Bucket and I am completely able to upload them there on bucket using this code.

model.py

class Evidence(models.Model):
    """
    Stores an individual evidence file, related to :model:`reporting.ReportFindingLink`
    and :model:`users.User`.
    """

    def set_upload_destination(self, filename):
        """
        Sets the `upload_to` destination to the evidence folder for the associated report ID.
        """
        return os.path.join("evidence", str(self.finding.report.id), filename)

    document = models.FileField(
        upload_to=set_upload_destination,
        validators=[validate_evidence_extension],
        blank=True,
    )
    finding = models.ForeignKey("ReportFindingLink", on_delete=models.CASCADE)

views.py

    def form_valid(self, form, **kwargs):
        self.object = form.save(commit=False)
        self.object.uploaded_by = self.request.user
        self.object.finding = self.finding_instance
        try:
            self.object.save()
            messages.success(self.request,"Evidence uploaded successfully", extra_tags="alert-success")
        except:
            messages.error(self.request, "Evidence file failed to upload", extra_tags="alert-danger")
        return HttpResponseRedirect(self.get_success_url())

    def get_success_url(self):
        if "modal" in self.kwargs:
            return reverse("reporting:upload_evidence_modal_success")
        return reverse("reporting:report_detail", args=(self.object.finding.report.pk,))

All of this is working fine. But trouble occurs when I am trying to delete the file. Huh?

Here is my code for deleting the file.

I must tell you guys that there is relationship established between Evidence and ReportingLink table.

class ReportFindingLinkDelete(LoginRequiredMixin, SingleObjectMixin, View):
    """
    Delete an individual :model:`reporting.ReportFindingLink`.
    """

    model = ReportFindingLink

    def post(self, *args, **kwargs):
        finding = self.get_object()
        finding.delete()
        data = {
            "result": "success",
            "message": "Successfully deleted {finding} and cleaned up evidence".format(finding=finding),
        }
        logger.info(
            "Deleted %s %s by request of %s",
            finding.__class__.__name__,
            finding.id,
            self.request.user,
        )

        return JsonResponse(data)

Above is the code for deletion of ReportLink which will eventually delete the Evidence.

What could the problem here?