1. A GET request with side-effects
2. A model with a …Model suffix
3. calling all() before count() or filter() etc.
4. Chaining querysets together
5. Checking if an object is created with instance.pk
6. Checking ownership through the UserPassesTestMixin
7. Checking request method with if request.POST
8. Constructing a new form when validation fails
9. Data duplication
10. Fetching the logged in user with a query
11. Fill the primary key gaps
12. Filter on arbitrary input like request.GET
13. Filtering in the template
14. Foreign key with _id suffix
15. Giving related_name=… the same name as the relation
16. Imports
17. Manually constructing a slug
18. Modifying slugs and primary keys of model objects
19. non-atomic JSONFields
20. (Over)use of .values()
21. passing function references to reverse
22. Passing parameters directly in the query string of a URL
23. Plural model class names
24. Processing request data manually
25. Refer to the User model directly
26. Rendering content after a successful POST request
27. Rendering into JavaScript
28. Return a JsonResponse with safe=False
29. Run makemigrations in production
30. Signals
31. Use datetime.now as default=… for a created_on field
32. Use .get(…) to retrieve the object in a view
33. Users controlling a primary key
34. Using a FloatField for currencies
35. Using commit=False when altering the instance in a ModelForm
36. Using len(…) on a QuerySet with no further use
37. Using multiple forms on the same page without prefixing
38. Using regular HTML comments instead of Django template comments
39. Using request.POST or None