Do Not Save Model On Duplicate File - Django 2

I am trying to check for an existing file and overwriting it, so far I am able to do it using a custom storage, which looks something like this from django.core.files.storage impor

Solution 1:

The condition, if instance.relative_path != 'null': is wrong. It should be just if instance.relative_path:

When I tried your snippet I felt something wrong with the user_directory_path function. So, I changed it to something like below.

def user_directory_path(instance, filename):
    """
    If relative path is not ``null`` the files will be stored as is else it will be
    stored to the root directory.

    The "relative_path" path should not be start or ends with a slash ("/") but, can use slash inside

    /foo/ -> Not allowed
    /foo/bar -> Not allowed
    foo/bar/ -> Not allowed

    foo -> Allowed
    foo/bar -> Allowed
    foo/bar/foobar -> Allowed

    """

    if instance.relative_path:
        relative_path = instance.relative_path
        if relative_path[0] == '/':
            relative_path = relative_path[1:]
        if relative_path[:-1] == '/':
            relative_path = relative_path[:-1]

        return 'user_{0}/{1}/{2}'.format(instance.user.id, relative_path, filename)
    return 'user_{0}/{1}'.format(instance.user.id, filename)

---

Now coming to our solution, I've created a sample view which will solve the issue.

from django.http.response import HttpResponse


def foo(request):
    if request.method == 'POST':
        create_data = {
            "user_id": request.user.pk,
            "file": request.FILES['file_name']
        }

        ds_temp = DataStorageModel(**create_data)
        path = user_directory_path(ds_temp, ds_temp.file.name)
        try:
            ds_existing = DataStorageModel.objects.get(file=path)
            ds_existing.file = create_data['file']
            ds_existing.save()
            return HttpResponse("instance modified")
        except DataStorageModel.DoesNotExist:
            ds_temp.save()
            return HttpResponse("new instance created")
    return HttpResponse("HTTP GET method")