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Red User, Blue User, MyUser, auth.User Dr Russell Keith-Magee DjangoCon US 2013

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Image Source: Amazon.com

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Why should we care?

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Login using email address

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Associating profile data with the User model

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What’s in a name?

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class User(Model): first_name = CharField(max_length=30) last_name = CharField(max_length=30)

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WTF?

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⽑毛泽东 Mao Zedong Image Source: Wikipedia

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Yao Ming Image Source: Wikipedia

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Björk Guðmundsdóttir Image Source: IMDB

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Mahathir bin Mohamad Image Source: Wikipedia

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Mohd. Anwar El Sadat Image Source: Wikipedia

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Aránzazu Isabel María Sánchez Vicario Image Source: Wikipedia

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Ayrton Senna da Silva Image Source: Wikipedia

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Stilgherrian Image Source: stilgherrian.com/about; ©2009 Trinn (’Pong) Suwannaph; Used with permission

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www.w3.org/International/questions/qa-personal-names

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class User(Model): first_name = CharField(max_length=30) last_name = CharField(max_length=30)

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class User(Model): first_name = CharField(max_length=100) last_name = CharField(max_length=100) NOPE

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class User(Model): christian_name = CharField(max_length=10) middle_initial = CharField(max_length=1) last_name = CharField(max_length=10)

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Names are hard. Lets go shopping.

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Do you really need separate fields? Full name

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If you do, don’t use first/last name. Family name Other/Given names

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“How would you like to be addressed?”

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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

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On the subject of “do you need to ask”...

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http://www.tizag.com/phpT/examples/formex.php

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Kuzdu and the California Marriage Amendment http://linuxmafia.com/faq/Essays/marriage.html

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When it comes to questions of identity: You need to think

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Do I need to ask at all?

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Custom User Models

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This is all in the docs.

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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()

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2. Define your Manager • Need to describe: • How to create users • How to create superusers

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3. Define forms • UserCreationForm • UserChangeForm • PasswordResetForm (maybe)

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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

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5. Register model • In settings, define: AUTH_USER_MODEL = ‘myapp.MyUser’

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6. Update Foreign Keys • Before: • ForeignKey(User) • After: • ForeignKey(settings.AUTH_USER_MODEL)

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Documented Gotchas

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USERNAME_FIELD must be unique and not in REQUIRED_FIELDS

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Signal registration

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What isn’t in the docs?

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Reverse lookup naming

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Reverse lookup naming class Department(Model): ... class User(AbstractUser): full_name = CharField() department = ForeignKey(Department) department = Department.objects.get(...) print department.user_set.all()

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Reverse lookup naming class Department(Model): ... class MyUser(AbstractUser): full_name = CharField() department = ForeignKey(Department) department = Department.objects.get(...) print department.myuser_set.all()

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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()

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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()

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The User Contract

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Examples of use

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Email based login

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Email-based login • Define a user model with • email = EmailField(max_length=254) • USERNAME_FIELD = ‘email’ • Define forms, admin, etc • Set AUTH_USER_MODEL

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Better yet: Don’t reinvent the wheel!

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Ticket #20824

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API-based login

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Kerberos Single Sign-on

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Kerberos Single Sign-on • “username” is your Kereros token: username@domain • Define an authentication backend that converts credentials into users

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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.

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www.roguelynn.com /words/django-custom-user-models/

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Profile data

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Option 1 class User(AbstractUser): full_name = CharField() birth_date = DateField() avatar = FileField()

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Option 2: class User(AbstractUser): ... class UserProfile(Model): full_name = CharField() user = OneToOneField(User) birth_date = DateField() avatar = FileField()

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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()

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Option 3: Hybrid class User(AbstractUser): full_name = CharField() class UserProfile(Model): user = OneToOneField(User) birth_date = DateField() avatar = FileField()

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So which approach should you use?

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It depends.

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Broadly: Profiles are better architecture

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But: there’s a cost

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Where to draw the line for the hybrid models?

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One more thing...

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How does it all work?

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THE FOLLOWING SLIDES WILL SELF DESTRUCT AFTER THIS PRESENTATION

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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

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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.

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The dirty secret: You can make your own models swappable.

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Questions? http://cecinestpasun.com russell@keith-magee.com @freakboy3742