I am developing a Django application where users can upload files associated with specific topics and submissions. Despite setting up everything according to the Django documentation, the files do not appear in the specified media directory or in the database after upload. I am using Django 5.0.4 and Python 3.10.

Models.py:

class File(models.Model):
    topic = models.ForeignKey(Topic, related_name='files', on_delete=models.CASCADE, null=True)
    submission = models.ForeignKey(Submission, related_name='files', on_delete=models.CASCADE, null=True)
    filename = models.FileField(upload_to='submissions/', null=True)
    upload_date = models.DateTimeField(auto_now_add=True)
    is_accepted = models.BooleanField(default=False)
     
    def __str__(self):
        return f"File: {self.filename.name} for Topic: {self.topic.name}"
    

Forms.py:

class UploadFileForm(ModelForm):
    class Meta:
        model = File
        fields = ('filename',)
  

Views.py:

def upload_file(request, subm_id, topic_id):
    submission = get_object_or_404(Submission, pk=subm_id)
    topic = get_object_or_404(Topic, pk=topic_id)
    form = UploadFileForm()
    context = {'submission':submission, 'topic':topic, 'form': form}
    
    if request.method == 'POST':
        form = UploadFileForm(request.POST, request.FILES)
        
        if form.is_valid(): 
            file_instance = form.save(commit=False)
            file_instance.topic = topic
            file_instance.submission = submission
            file_instance.save()
            messages.success(request, 'File succesfully uploaded')
            return redirect('upload_file', subm_id=submission.id, topic_id=topic.id)
        else:
            print(request.FILES)
            messages.error(request, 'No file was uploaded')
            form = UploadFileForm()
    return render(request, 'users/upload_file.html', context=context)

Settings.py:

MEDIA_URL = '/media/'
MEDIA_ROOT = BASE_DIR / 'media'

Template:

<form method="POST" action="" enctype="multipart/form-data">
            {% csrf_token %}
            <div class="mb-3">
              <label class="form-label" for="{{ form.filename.id_for_label}} "
                >Загрузите файл</label
              >
              {{ form|crispy }}
            </div>
            <input class="btn btn-secondary" type="submit" value="Submit" />
          </form>

What could be causing this issue and how can I resolve it to ensure files are correctly uploaded and saved in Django?