rules:
- id: use-onetoonefield
  patterns:
  - pattern-inside: |
      class $M(...):
        ...
  - pattern: $F = django.db.models.ForeignKey(..., unique=True, ...)
  message: >-
    Use 'django.db.models.OneToOneField' instead of 'ForeignKey' with unique=True.
    'OneToOneField' is used to create one-to-one relationships.
  languages: [python]
  severity: WARNING
  metadata:
    category: best-practice
    technology:
    - django