👀 Views: 17 💬 Answers: 1 📅 Created: 2025-06-02

django models deletion foreignkey Python

This might be a silly question, but I've searched everywhere and can't find a clear answer. Quick question that's been bugging me - I'm currently working on a Django 4.0 application where I need to control the behavior of `ForeignKey` deletions. I have a `Comment` model that is linked to a `Post` model via a ForeignKey. The requirement is to delete all comments associated with a post when the post is deleted, but I need to implement additional logic to log the deletion of each comment before it is removed. Here's my model structure: ```python class Post(models.Model): title = models.CharField(max_length=200) content = models.TextField() class Comment(models.Model): post = models.ForeignKey(Post, on_delete=models.CASCADE) text = models.TextField() ``` When I try to override the `delete` method in the `Post` model like this: ```python def delete(self, *args, **kwargs): comments = self.comment_set.all() for comment in comments: # Custom logic to log the deletion print(f'Deleting comment: {comment.text}') # Replace with logging comment.delete() super().delete(*args, **kwargs) ``` I encounter the following behavior when attempting to delete a post: ``` RuntimeError: Model 'app_name.comment' has no relation with 'app_name.post'. ``` I've also tried using `prefetch_related` on the queryset to avoid this scenario, but it doesn't seem to resolve the question. Any advice on how I can properly implement this cascading delete with custom logging without running into this behavior would be greatly appreciated. I'm using PostgreSQL as the backend and have already defined the logging mechanism, just need help with the deletion logic. Any help would be greatly appreciated! This is part of a larger API I'm building. Is there a better approach?