Red User, Blue User, MyUser, auth.User

An exploration of one of the banner features of Django 1.5 -- Custom User models. Includes worked examples, a discussion of design decisions that must be made, and a look at the internal architecture that makes it all possible.

Transcript

1. Red User, Blue User, MyUser, auth.User Dr Russell Keith-Magee DjangoCon US 2013
4. Image Source: Amazon.com
5. Why should we care?
6. Login using email address
7. Associating profile data with the User model
8. What’s in a name?
9. class User(Model): first_name = CharField(max_length=30) last_name = CharField(max_length=30)
10. WTF?
11. ⽑毛泽东 Mao Zedong Image Source: Wikipedia
12. Yao Ming Image Source: Wikipedia
13. Björk Guðmundsdóttir Image Source: IMDB
14. Mahathir bin Mohamad Image Source: Wikipedia
15. Mohd. Anwar El Sadat Image Source: Wikipedia
16. Aránzazu Isabel María Sánchez Vicario Image Source: Wikipedia
17. Ayrton Senna da Silva Image Source: Wikipedia
18. Stilgherrian Image Source: stilgherrian.com/about; ©2009 Trinn (’Pong) Suwannaph; Used with permission
19. www.w3.org/International/questions/qa-personal-names
20. class User(Model): first_name = CharField(max_length=30) last_name = CharField(max_length=30)
21. class User(Model): first_name = CharField(max_length=100) last_name = CharField(max_length=100) NOPE
22. class User(Model): christian_name = CharField(max_length=10) middle_initial = CharField(max_length=1) last_name = CharField(max_length=10)
23. Names are hard. Lets go shopping.
24. Do you really need separate fields? Full name
25. If you do, don’t use first/last name. Family name Other/Given names
26. “How would you like to be addressed?”
27. Other tips • Don’t assume a single letter is an initial • Be wary of name-part algorithms • Spaces, Apostrophes and Hyphens are all legal characters in names • Don’t require a “family name” • “Previous name”, not “Maiden name” • Honorifics even more complex
28. On the subject of “do you need to ask”...
29. http://www.tizag.com/phpT/examples/formex.php
30. Kuzdu and the California Marriage Amendment http://linuxmafia.com/faq/Essays/marriage.html
31. When it comes to questions of identity: You need to think
32. Do I need to ask at all?
33. Custom User Models
34. This is all in the docs.
35. 1. Define user model • 2 possible abstract base classes: • AbstractBaseUser • AbstractUser • Maybe with PermissionsMixin • Define USERNAME_FIELD • Define REQUIRED_FIELDS • Define get_full_name() and get_short_name()
36. 2. Define your Manager • Need to describe: • How to create users • How to create superusers
37. 3. Define forms • UserCreationForm • UserChangeForm • PasswordResetForm (maybe)
38. 4. Register with admin • Only need to do this if you’re using admin • Subclass contrib.admin.UserAdmin • admin.site.register() • Don’t need to unregister default User
39. 5. Register model • In settings, define: AUTH_USER_MODEL = ‘myapp.MyUser’
40. 6. Update Foreign Keys • Before: • ForeignKey(User) • After: • ForeignKey(settings.AUTH_USER_MODEL)
41. Documented Gotchas
42. USERNAME_FIELD must be unique and not in REQUIRED_FIELDS
43. Signal registration
44. What isn’t in the docs?
45. Reverse lookup naming
46. Reverse lookup naming class Department(Model): ... class User(AbstractUser): full_name = CharField() department = ForeignKey(Department) department = Department.objects.get(...) print department.user_set.all()
47. Reverse lookup naming class Department(Model): ... class MyUser(AbstractUser): full_name = CharField() department = ForeignKey(Department) department = Department.objects.get(...) print department.myuser_set.all()
48. Reverse lookup naming class Department(Model): ... class MyUser(AbstractUser): full_name = CharField() department = ForeignKey(Department, related_name=‘user_set’) department = Department.objects.get(...) print department.user_set.all()
49. Reverse lookup naming class Department(Model): ... class MyUser(AbstractUser): full_name = CharField() department = ForeignKey(Department) department = Department.objects.get(...) attr = “%s_set” % user._meta.object_name print getattr(department,attr).all()
50. The User Contract
51. Examples of use
52. Email based login
53. Email-based login • Define a user model with • email = EmailField(max_length=254) • USERNAME_FIELD = ‘email’ • Define forms, admin, etc • Set AUTH_USER_MODEL
54. Better yet: Don’t reinvent the wheel!
55. Ticket #20824
56. API-based login
57. Kerberos Single Sign-on
58. Kerberos Single Sign-on • “username” is your Kereros token: username@domain • Define an authentication backend that converts credentials into users
59. Authentication Backends • On login, you provide a credentials dict • Usually, Username and Password • Can be anything • Authentication backend turns credentials into a validated user • Can have multiple authentication backends.
60. www.roguelynn.com /words/django-custom-user-models/
61. Profile data
62. Option 1 class User(AbstractUser): full_name = CharField() birth_date = DateField() avatar = FileField()
63. Option 2: class User(AbstractUser): ... class UserProfile(Model): full_name = CharField() user = OneToOneField(User) birth_date = DateField() avatar = FileField()
64. Option 2: class User(AbstractUser): ... class IdentityProfile(Model): user = OneToOneField(User) full_name = CharField() birth_date = DateField() class DisplayProfile(Model): user = OneToOneField(User) avatar = FileField()
65. Option 3: Hybrid class User(AbstractUser): full_name = CharField() class UserProfile(Model): user = OneToOneField(User) birth_date = DateField() avatar = FileField()
66. So which approach should you use?
67. It depends.
68. Broadly: Profiles are better architecture
69. But: there’s a cost
70. Where to draw the line for the hybrid models?
71. One more thing...
72. How does it all work?
73. THE FOLLOWING SLIDES WILL SELF DESTRUCT AFTER THIS PRESENTATION
74. How it works • No internal references to auth.User • auth.User has a Meta property: swappable = ‘AUTH_USER_MODEL’ • Defines the name of a setting • Inspected at runtime for the “real” class • generates Meta.swapped • The rest is just validation
75. ForeignKeys + M2M • No new features in ForeignKey or M2M • ForeignKey(‘auth.User’) has always worked • Now, we’re just using a setting • Validation that ForeignKey doesn’t point at a “swapped” model.
76. The dirty secret: You can make your own models swappable.
78. Questions? http://cecinestpasun.com russell@keith-magee.com @freakboy3742