DjangoCon US 2016: Mighty Model Managers

These slides accompany a talk I gave at DjangoCon US 2016 called "Mighty Model Managers". The abstract can be seen here: https://2016.djangocon.us/schedule/presentation/62/

Transcript

1. Mighty Model Managers DjangoCon US 2016 Shawn Inman @shawninman
2. Why Are We Here?
3. Why Are We Here?
4. Managing Complexity • For our users • In business processes • If we do it right, even for ourselves
6. Why Model Managers? • Improved semantics • Readability • Encapsulation of logic • Ease of maintenance
7. What Are Model Managers?
8. Default Manager
9. The Job To Be Done 1. Provide a QuerySet for its model 2. Provide table-level functionality
10. Customization !
11. Our Task
12. Semantics
13. Readability Is Important!
15. Does It Really Matter?
16. Encapsulation
17. Encapsulation
18. Encapsulation
19. Multiple Managers
20. Multiple Managers
21. Drawbacks • No chaining custom operations • Lots of subclass can feel heavy
22. QuerySet Subclass
23. Using Our New Manager
24. Changes In Scope
25. Additional Filters
26. Additional Filters
27. Additional Filters
28. Removing Redundancy • There’s a lot of redundancy here…
29. Removing Redundancy We can remove the manager entirely!
30. Preventing Mistakes • Protect future-you from present-you • Really, really easy to forget to filter out inactive records
31. Preventing Mistakes
32. One Caveat • Not overriding default query set • .all() returns inactive records
33. Test Coverage
34. Stick Around I Didn’t Know Querysets Could Do That 5:10 Auditorium
35. Shout Out " Docs Contributors
36. Questions? @shawninman