Inappropriate Cascade

Description

This check ensures that the CASCADE option is not used inappropriately for the on_delete parameter in ForeignKey fields, as it can lead to unexpected data loss when a related object is deleted.

Rationale

Using CASCADE for the on_delete parameter in ForeignKey fields can result in the deletion of related objects when the referenced object is deleted. While this may be appropriate in some cases, other options like SET_NULL or PROTECT can be safer alternatives depending on the application's requirements.

Example

Consider the following model:

from django.db import models

class Author(models.Model):
    name = models.CharField(max_length=100)

class Book(models.Model):
    title = models.CharField(max_length=100)
    author = models.ForeignKey(Author, on_delete=models.CASCADE)

The author field is a ForeignKey field and is using the CASCADE option for on_delete. The check would detect this and recommend considering alternative options:

author = models.ForeignKey(Author, on_delete=models.SET_NULL, null=True)
# or
author = models.ForeignKey(Author, on_delete=models.PROTECT)

Evaluate the impact of using CASCADE on your application's data integrity and choose the appropriate option based on your specific use case.