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     Antipatterns

    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

     Patterns

    1. A SET(…) delete handler with the object as parameter
    2. Annotate a condition as BooleanField
    3. Date(Time)Fields that store a week or month
    4. Dictionary lookups for the database
    5. Match multiple strings in a case-insensitive manner
    6. querying in the opposite direction
    7. Set values to a created/updated object in a class-based view

     Difference between …

    1. ForeignKey and OneToOneField
    2. reverse and redirect

     Troubleshooting

    1. A certain field does not appear in the migrations and in the database table
    2. Can not extract/filter a Date(Time)Field when time zones are enabled

     QA

    1. How do calls of models.Manager and custom managers work?