Django: update audio duration in database if the associated audio file was updated by user

receivers.py

# considering model has audio_field = FileField()


def some_pre_save_receiver(sender, instance, raw, using, update_fields, **kwargs):

    file_was_updated = False
    if hasattr(instance.audio_file, 'file') and isinstance(instance.audio_file.file, UploadedFile):
        file_was_updated = True

    if update_fields and "audio_file" in update_fields:
        file_was_updated = True

    print(f">>  pre_save receiver executed, update fields: {update_fields}, file_was_updated: {file_was_updated}")

    if file_was_updated:
        # read audio file metadata
        audio_info = mutagen.File(instance.audio_file).info
        # set audio duration in seconds, so we can access it in database
        instance.duration_seconds = int(audio_info.length)

        print(">> audio duration was was updated")

    else:
        print(">> file not changed - duration was NOT updated")