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![SELF AWARE MODELclassSelfAwareModel(models.Model): def get_ct( self ):''' Returns the Content Type for this instance'''return ContentType.objects.get_for_model(self)def get_ct_id( self ):''' Returns the id of the content type for this instance'''return self.get_ct().pkdef get_app_label( self ):return self.get_ct().app_labeldef get_model_name( self ):return self.get_ct().modelclassMeta: abstract = TrueCACHED BY DJANGOself.__class__._cache[self.db][key]](https://image.slidesharecdn.com/mkemeetup-contenttypes-7-13-2011-110713225855-phpapp02/75/Powerful-Generic-Patterns-With-Django-38-2048.jpg)
![REAL GENERIC VIEWdefobject_detail( request, ct_id, obj_id, template=None ): type = ContentType.objects.get( pk = ct_id ) model = type.model_class() obj = model._default_manager.get( pk = ct_id )if template isNone: template = '%s_detail.html'%(type)return render_to_response( template )Might Want To Cache Thatself.__class__._cache[self.db][key]](https://image.slidesharecdn.com/mkemeetup-contenttypes-7-13-2011-110713225855-phpapp02/75/Powerful-Generic-Patterns-With-Django-49-2048.jpg)
![UNIVERSAL URLsurlpatterns = patterns( 'myproj.myapp', url( r'^(?P<slug>[-\w]+)/(?P<ct_id>\d+)/list/$', 'object_list',name='my_proj_content_list' ), url( r'^(?P<slug>[-\w]+)/(?P<ct_id>\d+)-(?P<obj_id>\d+)/$','object_detail',name="my_proj_content_detail" ), url( r'^(?P<slug>[-\w]+)/(?P<ct_id>\d+)-(?P<obj_id>\d+)/edit/$', 'object_edit',name="my_proj_content_edit" ) ...)](https://image.slidesharecdn.com/mkemeetup-contenttypes-7-13-2011-110713225855-phpapp02/75/Powerful-Generic-Patterns-With-Django-57-2048.jpg)
![MAGIC FORMSdefform_class_for( obj, includes=[] excludes=[] ): modelclass = obj.get_ct().model_class()class_MagicForm(forms.ModelForm): ...classMeta: model= modelclassif includes: fields = includesif excludes: exclude = excludes return _MagicForm](https://image.slidesharecdn.com/mkemeetup-contenttypes-7-13-2011-110713225855-phpapp02/75/Powerful-Generic-Patterns-With-Django-64-2048.jpg)
![MAGIC FORMSdefform_class_for( obj, includes=[] excludes=[] ): modelclass = obj.get_ct().model_class()class_MagicForm(forms.ModelForm): ...classMeta: model= modelclassif includes: fields = includesif excludes: exclude = excludes return _MagicFormDON'T KNOW](https://image.slidesharecdn.com/mkemeetup-contenttypes-7-13-2011-110713225855-phpapp02/75/Powerful-Generic-Patterns-With-Django-65-2048.jpg)
![MAGIC FORMSdefform_class_for( obj, includes=[] excludes=[] ): modelclass = obj.get_ct().model_class()class_MagicForm(forms.ModelForm): ...classMeta: model= modelclassif includes: fields = includesif excludes: exclude = excludes return _MagicFormDON'TCARE](https://image.slidesharecdn.com/mkemeetup-contenttypes-7-13-2011-110713225855-phpapp02/75/Powerful-Generic-Patterns-With-Django-66-2048.jpg)
![MAGIC FORMSdefform_class_for( obj, includes=[] excludes=[] ): modelclass = obj.get_ct().model_class()class_MagicForm(forms.ModelForm): ...classMeta: model= modelclassif includes: fields = includesif excludes: exclude = excludes return _MagicFormPERFECTLYLEGAL](https://image.slidesharecdn.com/mkemeetup-contenttypes-7-13-2011-110713225855-phpapp02/75/Powerful-Generic-Patterns-With-Django-67-2048.jpg)
Uploaded byEric Satterwhite
Powerful Generic Patterns With Django
The document discusses Django's contenttypes framework which allows working with models generically without having to know the specific model being used. It presents several patterns for implementing generic functionality, including self-aware models, improved generic views, universal URLs, and dynamic forms. The key benefits are the ability to perform CRUD operations and create relationships between any objects without having to pre-program for each specific model.
Powerful Generic Patterns With Django
- 2. POWERFUL GENERIC PATTERNSDjango'sContent Types Framework
- 3. CONTENTTYPESAn application thatcan track all of the models installed in your Django-powered project, providing a high-level, generic interface for working with your models
- 4.
- 5. CONTENTTYPES----------------------------------------| name | app_label | model || post | blogger | post || blog | blogger | Blog || like | likeable | Like |----------------------------------------
- 6. PROBLEMblog = Blog.objects.get(pk = 1 )posts = Post.objects.filter( blog = blog )features = Post.objects.filter( feature = True )3+ URLs3+ view function3+ templates
- 7. PROBLEMblog = Blog.objects.get(pk = 1 )posts = Post.objects.filter( blog = blog )features = Post.objects.filter( feature = True ){%for post in posts %}{{ post.title }} {{ post.like_set.count }} likes{%endfor%}
- 8.
- 9. GENERIC VIEWS?Take certaincommon idioms and patterns found in view development and abstract them so that you can quickly write common views of data without having to write too much code
- 10. GENERIC VIEWS?from django.views.genericimport list_detaildefmy_view( request ):return list_detail.object_list( queryset=Post.objects.all() )
- 11. NOT SO GENERICVIEWSfrom django.views.generic import list_detaildefmy_view( request ):return list_detail.object_list( queryset=Post.objects.all() )
- 12. NOT SO GENERICVIEWS
- 13. NOT SO GENERICVIEWSTo Use A Generic View You Need...A Queryset
- 14.
- 15. A Model +Slug
- 16. A Model +Slug FieldMORE PROBLEMSclassPost(models.Model): title = models.CharField() blog = models.ForeignKey( Blog ) body = models.TextField() slug = models.SlugField() likers = models.ForeignKey( User ) likes = models.IntegerField()BlogPostPost LikesPost Likers
- 17. MORE PROBLEMSclassFeature(models.Model): title = models.CharField() post = models.ForeignKey( Post ) likers = models.ForeignKey( User ) likes = models.IntegerField()
- 18. CONTENTTYPESAn application thatcan track all of the models installed in your Django-powered project, providing a high-level, generic interface for working with your models
- 19. CONTENTTYPESUse the ORMwithout knowing what kind of objects you might be working with.
- 20. CONTENTTYPESUse the ORMwithout knowing what kind of objects you might be working with. EVER.
- 21.
- 22. GENERIC FOREIGNKEYfrom django.contrib.contenttypes.modelsimportContentTypefrom django.contrib.contenttypes importgenericclassFeature(models.Model): content_type = models.ForeignKey (ContentType) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey('content_type' ,'object_id' )
- 23. MAGIC BITSclassFeature(models.Model): content_type = models.ForeignKey (ContentType) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey( 'content_type' ,'object_id' )
- 24. MAGIC BITSclassFeature(models.Model): content_type = models.ForeignKey (ContentType) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey('content_type' ,'object_id' )
- 25. MAGIC BITSclassFeature(models.Model): content_type = models.ForeignKey (ContentType) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey('content_type' ,'object_id' )
- 26. GENERIC FOREIGNKEY>>> obj = Feature.objects.get( pk = 1 )>>> obj.content_object>>> <Post: Hello World>>>> obj = Feature.objects.get( pk = 2 )>>> obj.content_object>>> <Blog: The Best Blog>>>> obj = Feature.objects.get( pk = 3 )>>> obj.content_object>>> <Anything: Whatever You Want>
- 27.
- 28. GENERIC FOREIGNKEYclassPost(models.Model): title = models.CharField() blog = models.ForeignKey( Blog ) body = models.TextField() slug = models.SlugField()classLike( models.Model ): content_type = models.ForeignKey( ContentType ) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey( ... ) likers = models.ManyToMany( User )
- 29. GOTCHA!Models are NOTaware of their Content Type
- 30. MORE PROBLEMSclassLike( models.Model): content_type = models.ForeignKey( ContentType ) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey( ... ) likers = models.ManyToMany( User )
- 31. MORE PROBLEMSclassLike( models.Model): content_type = models.ForeignKey( ContentType ) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey( ... ) likers = models.ManyToMany( User )deflike_view( request, object_id ): post = Post.objects.get( pk = object_id ) like = Like( object_id = post, ??? )
- 32. GENERIC GEMSfrom django.contrib.contenttypes.modelsimportContentTypefrom django.contrib.auth.models importUser>>> type = ContentType.objects.get_for_model( User )>>> type>>> <ContentType: user >>>> model = type.model_class()>>> model>>> <class: 'django.contrib.auth.models.User'>
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- 34.
- 35.
- 36. SELF AWARE MODELclassSelfAwareModel(models.Model): def get_ct( self ):''' Returns the Content Type for this instance'''return ContentType.objects.get_for_model(self)def get_ct_id( self ):''' Returns the id of the content type for this instance'''return self.get_ct().pkdef get_app_label( self ):return self.get_ct().app_labeldef get_model_name( self ):return self.get_ct().modelclassMeta: abstract = True
- 37. SELF AWARE MODELclassSelfAwareModel(models.Model): def get_ct( self ):''' Returns the Content Type for this instance'''return ContentType.objects.get_for_model(self)def get_ct_id( self ):''' Returns the id of the content type for this instance'''return self.get_ct().pkdef get_app_label( self ):return self.get_ct().app_labeldef get_model_name( self ):return self.get_ct().modelclassMeta: abstract = TrueCACHED BY DJANGO
- 38. SELF AWARE MODELclassSelfAwareModel(models.Model): def get_ct( self ):''' Returns the Content Type for this instance'''return ContentType.objects.get_for_model(self)def get_ct_id( self ):''' Returns the id of the content type for this instance'''return self.get_ct().pkdef get_app_label( self ):return self.get_ct().app_labeldef get_model_name( self ):return self.get_ct().modelclassMeta: abstract = TrueCACHED BY DJANGOself.__class__._cache[self.db][key]
- 39. SELF AWARE EVERYTHINGclassPost(SelfAwareModel ): title = models.CharField() blog = models.ForeignKey( Blog ) body = models.TextField() slug = models.SlugField() likers = models.ForeignKey( User ) likes = models.IntegerField()
- 40. SELF AWARE EVERYTHINGclassPost(SelfAwareModel ): title = models.CharField() blog = models.ForeignKey( Blog ) body = models.TextField() slug = models.SlugField() likers = models.ForeignKey( User ) likes = models.IntegerField()ALL MODELSSUBCLASSESELFAWAREMODEL
- 41. SELF AWARE EVERYTHINGclassPost(SelfAwareModel ): title = models.CharField() blog = models.ForeignKey( Blog ) body = models.TextField() slug = models.SlugField() likers = models.ForeignKey( User ) likes = models.IntegerField()@permalinkdef get_absolute_url( self ): ...>>> post = Post.objects.latest()>>> obj.get_ct()>>> <ContentType: post>
- 42. SELF AWARE EVERYTHINGclassPost(SelfAwareModel ): title = models.CharField() blog = models.ForeignKey( Blog ) body = models.TextField() slug = models.SlugField() likers = models.ForeignKey( User ) likes = models.IntegerField()@permalinkdef get_absolute_url( self ): ...I KNOW MYCONTENT TYPE>>> post = Post.objects.latest()>>> obj.get_ct()>>> <ContentType: post>
- 43.
- 44.
- 45. REAL GENERIC VIEWdefobject_list(request, ct_id ... ): type = ContentType.objects.get( pk = ct_id ) model = type.model_class() obj_list = model._default_manager.all()return render_to_response( ... )
- 46. REAL GENERIC VIEWdefobject_detail(request, ct_id, obj_id, template=None ): type = ContentType.objects.get( pk = ct_id ) model = type.model_class() obj = model._default_manager.get( pk = ct_id )if template isNone: template = '%s_detail.html'%(type)return render_to_response( template )
- 47. REAL GENERIC VIEWdefobject_detail(request, ct_id, obj_id, template=None ): type = ContentType.objects.get( pk = ct_id ) model = type.model_class() obj = model._default_manager.get( pk = ct_id )if template isNone: template = '%s_detail.html'%(type)return render_to_response( template )
- 48. REAL GENERIC VIEWdefobject_detail(request, ct_id, obj_id, template=None ): type = ContentType.objects.get( pk = ct_id ) model = type.model_class() obj = model._default_manager.get( pk = ct_id )if template isNone: template = '%s_detail.html'%(type)return render_to_response( template )Might Want To Cache That
- 49. REAL GENERIC VIEWdefobject_detail(request, ct_id, obj_id, template=None ): type = ContentType.objects.get( pk = ct_id ) model = type.model_class() obj = model._default_manager.get( pk = ct_id )if template isNone: template = '%s_detail.html'%(type)return render_to_response( template )Might Want To Cache Thatself.__class__._cache[self.db][key]
- 50. cPickle & noSQLDB ( Redis )REAL GENERIC VIEWproject|| - likeables/|| - blog/ | |- templates/ | |- blog/ | -post_list.html | -post_detail.html | -urls.py|| - templates/| - object_list.html| - object_detail.html| - urls.py
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- 52.
- 53.
- 54.
- 55.
- 56.
- 57. UNIVERSAL URLsurlpatterns =patterns( 'myproj.myapp', url( r'^(?P<slug>[-\w]+)/(?P<ct_id>\d+)/list/$', 'object_list',name='my_proj_content_list' ), url( r'^(?P<slug>[-\w]+)/(?P<ct_id>\d+)-(?P<obj_id>\d+)/$','object_detail',name="my_proj_content_detail" ), url( r'^(?P<slug>[-\w]+)/(?P<ct_id>\d+)-(?P<obj_id>\d+)/edit/$', 'object_edit',name="my_proj_content_edit" ) ...)
- 58.
- 59.
- 60. MAGIC FORMSdefedit_object( request,ct_id, obj_id ): obj = utils.get_object( ct_id, obj_id )
- 61. MAGIC FORMSdefedit_object( request,ct_id, obj_id ): obj = utils.get_object( ct_id, obj_id ) form = ???
- 62. MAGIC FORMSdefedit_object( request,ct_id, obj_id ): obj = utils.get_object( ct_id, obj_id ) form = ???Can't predefine ModelForm when you don't know what model you're working with
- 63.
- 64. MAGIC FORMSdefform_class_for( obj,includes=[] excludes=[] ): modelclass = obj.get_ct().model_class()class_MagicForm(forms.ModelForm): ...classMeta: model= modelclassif includes: fields = includesif excludes: exclude = excludes return _MagicForm
- 65. MAGIC FORMSdefform_class_for( obj,includes=[] excludes=[] ): modelclass = obj.get_ct().model_class()class_MagicForm(forms.ModelForm): ...classMeta: model= modelclassif includes: fields = includesif excludes: exclude = excludes return _MagicFormDON'T KNOW
- 66. MAGIC FORMSdefform_class_for( obj,includes=[] excludes=[] ): modelclass = obj.get_ct().model_class()class_MagicForm(forms.ModelForm): ...classMeta: model= modelclassif includes: fields = includesif excludes: exclude = excludes return _MagicFormDON'TCARE
- 67. MAGIC FORMSdefform_class_for( obj,includes=[] excludes=[] ): modelclass = obj.get_ct().model_class()class_MagicForm(forms.ModelForm): ...classMeta: model= modelclassif includes: fields = includesif excludes: exclude = excludes return _MagicFormPERFECTLYLEGAL
- 68. FULL CIRCLEdefedit_object( request,ct_id, obj_id ): obj = utils.get_object( ct_id, obj_id ) formclass = utils.get_form_for( obj ) form = formclass()return render_to_response( ... {'form':form} )
- 69. FULL CIRCLEdefedit_object( request,ct_id, obj_id ): obj = utils.get_object( ct_id, obj_id ) formclass = utils.get_form_for( obj ) form = formclass()return render_to_response( ... {'form':form} )DON'T KNOW
- 70. FULL CIRCLEdefedit_object( request,ct_id, obj_id ): obj = utils.get_object( ct_id, obj_id ) formclass = utils.get_form_for( obj ) form = formclass()return render_to_response( ... {'form':form} )DON'TCARE
- 71. DEAD SIMPLE{%urlmy_proj_content_list ct_id=obj.get_ct_id%}{%urlmy_proj_content_detail slug=obj.slug, ct_id=obj.get_ct_id, obj_id=obj.pk %}{%urlmy_proj_content_edit slug=obj.slug, ct_id=obj.get_ct_id, obj_id=obj.pk %}
- 72.
- 73. SCALE IT OUTDefineA ModelSync DBMake A Template ( Maybe ? )Rinse Repeate
- 74. PATTERNS RECAPSelf AwareModels
- 75. Better Generic Views& utilities
- 76.
- 77. Magic FormsPATTERNS RECAPSelfAware Models
- 78. Better Generic Views& utilities
- 79.
- 80. Magic FormsYou canperform CRUD ops and create any kind of relationship on any kind of object at anytimewithout programming for every situation.
- 81.