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