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The Django Book, Chapter 16: django.contrib

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Tzu-ping Chung
Tzu-ping Chung

Discusses Chapter 16 of The Django Book, and some other django.contrib packages such as ContentTypes, Comments, etc.

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django.contrib 2013-09-02. Django Workshop.
About me • TP (@uranusjr) • RTFD • Find me anywhere
django.contrib • Utilities • Optional • Don’t (need to) re-invent the wheels • These serves as examples if you want! • May change in the future
django.contrib • Utilities • Optional • Don’t (need to) re-invent the wheels • These serves as examples if you want! • May change in the future
Major changes Since 1.3 Packages Major changesMajor changes Packages Since Notes auth 1.5 Custom user model; get_profile() deprecated formtools 1.4 Reimplemented with CBVs staticfiles 1.4 New {%  static  %} template tag localflavor 1.5 Deprecated markup 1.5 Deprecated
django.contrib • Site-building tools • Auth & auth, sessions, etc. • Utilities • Page generation, messaging, etc. • Black magic
django.contrib • Site-building tools • Auth & auth, sessions, etc. • Utilities • Page generation, messaging, etc. • Black magic
Previously, on TDB... • admin (Chapter 6) • sitemaps, syndication (Chapter 13) • auth, sessions (Chapter 14)
CSRF Protection • CSRF: Cross-Site Request Forgery • Prevention • Use POST for state-changing processes • Add a token to every POST form • Only allow POST when the form has an appropriate token value
django.contrib.csrf • Depends on django.contrib.sessions • Template tag {%  csrf_token  %} • Middleware CsrfMiddleware • Beware of its limitations! • AJAX contents • Don’t use @csrf_exempt unless needed
django.contrib.sites • Sharing a data base between multiple sites • Site:A name and a domain • A SITE_ID in settings.py • The Site model • Site.objects.get_current() • The CurrentSiteManager
Content-Serving • django.contrib.flatpages • Reuse templates for “static” web pages without redundant views • django.contrib.redirects • Manage redirections in the database • django.contrib.admindocs
Cool Thingz • django.contrib.formtools • Split Django form into multiple pages • django.contrib.gis • GeoDjango • django.contrib.humanize • django.contrib.webdesign
Questions?
The Django Book, Chapter 16: django.contrib
Django’s void  * • Django’s relations require concrete targets • Multi-table subclassing is costly • A “pointer to anything”
It’s Possible • Python uses duck-typing already • Magic built-in: getattribute • Django’s get_model • Django relations are just ids
ContentTypes • GenericForeignKey • GenericRelation • Forms and formsets • Admin inlines
But How? • A ContentType model • post_syncdb.connect(update_contenttypes) • GenericForeignKey needs two helping fields • A ForeignKey to ContentType • A field to hold the primary key (usually a PositiveIntegerField)
from  django.db  import  models from  django.contrib.contenttypes  import  generic class  Attachment(models.Model):        attached_file  =  models.FileField(...)        content_type  =  models.ForeignKey(                'contenttypes.ContentType'        )        object_id  =  models.PositiveIntegerField()        content_object  =  generic.GenericForeignKey(                'content_type',  'object_id'        )        #  ...  blah  blah  blah  ...
from  django.db  import  models from  django.contrib.contenttypes  import  generic class  Attachment(models.Model):        attached_file  =  models.FileField(...)        content_type  =  models.ForeignKey(                'contenttypes.ContentType'        )        object_id  =  models.PositiveIntegerField()        content_object  =  generic.GenericForeignKey(                'content_type',  'object_id'        )        #  ...  blah  blah  blah  ...
from  django.db  import  models from  django.contrib.contenttypes  import  generic class  Attachment(models.Model):        attached_file  =  models.FileField(...)        content_type  =  models.ForeignKey(                'contenttypes.ContentType'        )        object_id  =  models.PositiveIntegerField()        content_object  =  generic.GenericForeignKey(                'content_type',  'object_id'        )        #  ...  blah  blah  blah  ...
from  django.db  import  models from  django.contrib.contenttypes  import  generic class  Attachment(models.Model):        attached_file  =  models.FileField(...)        content_type  =  models.ForeignKey(                'contenttypes.ContentType'        )        object_id  =  models.PositiveIntegerField()        content_object  =  generic.GenericForeignKey()        #  ...  blah  blah  blah  ...
post_attachments  =  Attachment.objects.filter(        content_object=BlogPost.objects.latest('id') ) taget_user  =  User.objects.get(username='uranusjr') message  =  Message.objects.filter(        from_user=request.user,  to_user=taget_user ).latest('created_at') message_attachment  =  Attachment.objects.filter(        content_object=message ) message_attachment.content_object  =  ... message_attachment.save()
Caveats • Not really a database field • Cannot filter (or exclude, get, etc.) • Cannot aggregate • Some annotations do work • No automatic reverse
from  django.db  import  models from  django.contrib.contenttypes  import  generic class  BlogPost(models.Model):        #  ...  blah  blah  blah  ...        attachments  =  generic.GenericRelation(Attachment)        #  ...  blah  blah  blah  ...
from  django.db  import  models from  django.contrib.contenttypes  import  generic class  BlogPost(models.Model):        #  ...  blah  blah  blah  ...        attachments  =  generic.GenericRelation(Attachment)        #  ...  blah  blah  blah  ... blog_post  =  BlogPost.objects.latest('id') #  These  two  become  equivalent Attachment.objects.filter(content_object=blog_post) blog_post.attachments
Applications • django.contrib.comments • django-ratings • Post tagging • “Like”
django.contrib • Utilities • Optional • Don’t (need to) re-invent the wheels • If you have to, these serves as examples • May change in the future
django.contrib • Site-building tools • Auth & auth, sessions, etc. • Utilities • Page generation, messaging, etc. • Black magic
django.contrib • Site-building tools • Auth & auth, sessions, etc. • Utilities • Page generation, messaging, etc. • Black magic • Hacks (in a good way!)
Questions?

More Related Content

The Django Book, Chapter 16: django.contrib

  • 2. About me • TP (@uranusjr) • RTFD • Find me anywhere
  • 3. django.contrib • Utilities • Optional • Don’t (need to) re-invent the wheels • These serves as examples if you want! • May change in the future
  • 4. django.contrib • Utilities • Optional • Don’t (need to) re-invent the wheels • These serves as examples if you want! • May change in the future
  • 5. Major changes Since 1.3 Packages Major changesMajor changes Packages Since Notes auth 1.5 Custom user model; get_profile() deprecated formtools 1.4 Reimplemented with CBVs staticfiles 1.4 New {%  static  %} template tag localflavor 1.5 Deprecated markup 1.5 Deprecated
  • 6. django.contrib • Site-building tools • Auth & auth, sessions, etc. • Utilities • Page generation, messaging, etc. • Black magic
  • 7. django.contrib • Site-building tools • Auth & auth, sessions, etc. • Utilities • Page generation, messaging, etc. • Black magic
  • 8. Previously, on TDB... • admin (Chapter 6) • sitemaps, syndication (Chapter 13) • auth, sessions (Chapter 14)
  • 9. CSRF Protection • CSRF: Cross-Site Request Forgery • Prevention • Use POST for state-changing processes • Add a token to every POST form • Only allow POST when the form has an appropriate token value
  • 10. django.contrib.csrf • Depends on django.contrib.sessions • Template tag {%  csrf_token  %} • Middleware CsrfMiddleware • Beware of its limitations! • AJAX contents • Don’t use @csrf_exempt unless needed
  • 11. django.contrib.sites • Sharing a data base between multiple sites • Site:A name and a domain • A SITE_ID in settings.py • The Site model • Site.objects.get_current() • The CurrentSiteManager
  • 12. Content-Serving • django.contrib.flatpages • Reuse templates for “static” web pages without redundant views • django.contrib.redirects • Manage redirections in the database • django.contrib.admindocs
  • 13. Cool Thingz • django.contrib.formtools • Split Django form into multiple pages • django.contrib.gis • GeoDjango • django.contrib.humanize • django.contrib.webdesign
  • 16. Django’s void  * • Django’s relations require concrete targets • Multi-table subclassing is costly • A “pointer to anything”
  • 17. It’s Possible • Python uses duck-typing already • Magic built-in: getattribute • Django’s get_model • Django relations are just ids
  • 18. ContentTypes • GenericForeignKey • GenericRelation • Forms and formsets • Admin inlines
  • 19. But How? • A ContentType model • post_syncdb.connect(update_contenttypes) • GenericForeignKey needs two helping fields • A ForeignKey to ContentType • A field to hold the primary key (usually a PositiveIntegerField)
  • 20. from  django.db  import  models from  django.contrib.contenttypes  import  generic class  Attachment(models.Model):        attached_file  =  models.FileField(...)        content_type  =  models.ForeignKey(                'contenttypes.ContentType'        )        object_id  =  models.PositiveIntegerField()        content_object  =  generic.GenericForeignKey(                'content_type',  'object_id'        )        #  ...  blah  blah  blah  ...
  • 21. from  django.db  import  models from  django.contrib.contenttypes  import  generic class  Attachment(models.Model):        attached_file  =  models.FileField(...)        content_type  =  models.ForeignKey(                'contenttypes.ContentType'        )        object_id  =  models.PositiveIntegerField()        content_object  =  generic.GenericForeignKey(                'content_type',  'object_id'        )        #  ...  blah  blah  blah  ...
  • 22. from  django.db  import  models from  django.contrib.contenttypes  import  generic class  Attachment(models.Model):        attached_file  =  models.FileField(...)        content_type  =  models.ForeignKey(                'contenttypes.ContentType'        )        object_id  =  models.PositiveIntegerField()        content_object  =  generic.GenericForeignKey(                'content_type',  'object_id'        )        #  ...  blah  blah  blah  ...
  • 23. from  django.db  import  models from  django.contrib.contenttypes  import  generic class  Attachment(models.Model):        attached_file  =  models.FileField(...)        content_type  =  models.ForeignKey(                'contenttypes.ContentType'        )        object_id  =  models.PositiveIntegerField()        content_object  =  generic.GenericForeignKey()        #  ...  blah  blah  blah  ...
  • 24. post_attachments  =  Attachment.objects.filter(        content_object=BlogPost.objects.latest('id') ) taget_user  =  User.objects.get(username='uranusjr') message  =  Message.objects.filter(        from_user=request.user,  to_user=taget_user ).latest('created_at') message_attachment  =  Attachment.objects.filter(        content_object=message ) message_attachment.content_object  =  ... message_attachment.save()
  • 25. Caveats • Not really a database field • Cannot filter (or exclude, get, etc.) • Cannot aggregate • Some annotations do work • No automatic reverse
  • 26. from  django.db  import  models from  django.contrib.contenttypes  import  generic class  BlogPost(models.Model):        #  ...  blah  blah  blah  ...        attachments  =  generic.GenericRelation(Attachment)        #  ...  blah  blah  blah  ...
  • 27. from  django.db  import  models from  django.contrib.contenttypes  import  generic class  BlogPost(models.Model):        #  ...  blah  blah  blah  ...        attachments  =  generic.GenericRelation(Attachment)        #  ...  blah  blah  blah  ... blog_post  =  BlogPost.objects.latest('id') #  These  two  become  equivalent Attachment.objects.filter(content_object=blog_post) blog_post.attachments
  • 29. django.contrib • Utilities • Optional • Don’t (need to) re-invent the wheels • If you have to, these serves as examples • May change in the future
  • 30. django.contrib • Site-building tools • Auth & auth, sessions, etc. • Utilities • Page generation, messaging, etc. • Black magic
  • 31. django.contrib • Site-building tools • Auth & auth, sessions, etc. • Utilities • Page generation, messaging, etc. • Black magic • Hacks (in a good way!)