feat: backend - book delete

signals folder created to hold every signals

on delete book, a signal delete the book file, cover image physically from the file directory

backend/book_api/apps.py

@@ -4,3 +4,7 @@
 class BookApiConfig(AppConfig):
     default_auto_field = 'django.db.models.BigAutoField'
     name = 'book_api'
+
+    def ready(self) -> None:
+        import book_api.signals # noqa
+        return super().ready()

backend/book_api/signals/__init__.py

@@ -0,0 +1,7 @@
+# book_api/signals/__init__.py
+from book_api.signals.book_delete import delete_book_files
+
+
+__all__ = [
+    delete_book_files,
+]

backend/book_api/signals/book_delete.py

@@ -0,0 +1,14 @@
+from django.db.models.signals import post_delete
+from django.dispatch import receiver
+
+from book_api.models import Book
+
+
+@receiver(post_delete, sender=Book)
+def delete_book_files(sender, instance, *args, **kwargs):
+    print(instance)
+    if instance.book:
+        instance.book.delete(save=False)
+
+    if instance.cover_image:
+        instance.cover_image.delete(save=False)