Usage

Adding a ConditionalGet mixin will make your class based views:

1. Calculate and append Etag and/or Last-Modified headers to each response and;
2. Return a 304 (Not Modified) or 412 (Precondition Failed) response if applicable.

In most cases, the predefined convenience mixins will be suitable for your views. Simply add the appropriate mixin to your view class to enable the functionality.

TemplateViews

The ConditionalGetTemplateViewMixin is appropriate for TemplateViews.

For example:

class MyView(ConditionalGetTemplateViewMixin, TemplateView):
  template_name = 'my_template.html'

class django_conditional_views.ConditionalGetTemplateViewMixin(**kwargs)

Conditional Request/Response aware mixin for TemplateView

Last-Modified: Calculated from the the template last modified timestamp.

Etag: Calculated from the rendered response.

last_modified_elements = [<class 'django_conditional_views.elements.last_modified.TemplateLastModified'>]

post_render_etag_elements = [<class 'django_conditional_views.elements.etag.RenderedContentEtag'>]

Model Views

The ConditionalGetDetailViewMixin is appropriate for DetailViews.

You may set the last_modified_field property on the view to control which field on the model contains the last modified timestamp. This field defaults to ‘modified’.

For example:

class MyModel(models.Model):
  name = models.CharField(max_length=255)
  modified = models.DateTimeField(auto_now=True)

class MyView(ConditionalGetDetailViewMixin, DetailView):
  model = MyModel

class MyOtherModel(models.Model):
  name = models.CharField(max_length=255)
  last_modified = models.DateTimeField(auto_now=True)

class MyOtherView(ConditionalGetDetailViewMixin, DetailView):
  model = MyModel
  last_modified_field = 'last_modified'

class django_conditional_views.ConditionalGetDetailViewMixin(**kwargs)

Conditional Request/Response aware mixin for DetailView

Last-Modified: Calculated from the latest of the template last modified timestamp and a configurable field on the model object, default ‘modified’.

Etag: Calculated from the rendered response.

last_modified_elements = None

post_render_etag_elements = [<class 'django_conditional_views.elements.etag.RenderedContentEtag'>]

The ConditionalGetListViewMixin is appropriate for ListViews.

You may set the last_modified_field property on the view to control which field on the model contains the last modified timestamp. This field defaults to ‘modified’. The most recent value for this field in the queryset will be used.

For example:

class MyModel(models.Model):
  name = models.CharField(max_length=255)
  modified = models.DateTimeField(auto_now=True)

class MyView(ConditionalGetListViewMixin, ListView):
  model = MyModel

class MyOtherModel(models.Model):
  name = models.CharField(max_length=255)
  last_modified = models.DateTimeField(auto_now=True)

class MyOtherView(ConditionalGetListViewMixin, ListView):
  model = MyModel
  last_modified_field = 'last_modified'

class django_conditional_views.ConditionalGetListViewMixin(**kwargs)

Conditional Request/Response aware mixin for ListView

Last-Modified: Calculated from the latest of the template last modified timestamp and the model objects ‘modified’ field.

Etag: Calculated from the rendered response.

last_modified_elements = None

post_render_etag_elements = [<class 'django_conditional_views.elements.etag.RenderedContentEtag'>]

Customizing Etag & Last-Modified Generation

The convenience mixins and the underlying ConditionalGetViewMixin compute the Etag and Last-Modified headers by calling a method which iterates through a list of elements stored in a property of the view class. See the individual header sections below for details.

Elements can be either a function or a class with a __call__ method (several useful base classes are provided in the django_conditional_views.elements module). Elements take the view instance as the only argument and return either None, a str (ETag) or a datetime.datetime (Last Modified).

To customize how either header is generated you may override the elements properties, define your own elements, or override the get methods entirely. See the API docs for details on the classes.

Last-Modified

The last-modified timestamp is calculated before the response is rendered by a call to the get_last_modified method, which by default takes the latest datetime returned by each function/object in the last_modified_elements view property.

Etag

Etags can be calculated both before and after the response is rendered. The benefit of calculating an etag before the response is rendered is that if the etag provided by the request matches the calculated etag, then the effort to render the response can be skipped.

Pre-render etags are computed by a call to the get_pre_rendered_etag method of the view, which by default calculates an etag by concatenating the output of each function/object in the pre_render_etag_elements view property.

Post-render etags are computed by a call to the get_post_rendered_etag method of the view, which by default calculates an etag by concatenating the output of each function/object in the post_render_etag_elements view property.