django-clsview

django-clsview is a library with yet another solution to the problem of class-based views in Django.

Installation

The usual:

pip install django-clsview  # OR
easy_install django-clsview

There’s no need to add djclsview to your INSTALLED_APPS setting.

Usage

Class-based views (CBVs) are classes which behave in a similar way to Django view functions. The underlying requirement for Django views is that they map requests to responses; by using classes, we get the benefits of inheritance to reduce boilerplate and increase reusability. There are many approaches to class-based views; this particular approach trades a very slight performance and memory footprint for simplicity and thread-safety.

You can point to a class-based view directly from the URLconf:

urlpatterns = patterns('',
    ...
    url(r'^view/$', 'myapp.views.MyView', name='my-view'),
    ...
)

To replicate the behavior of a function, __new__() has been overridden; calling ClassName(request, *args, **kwargs) will instantiate the class and then call the object (i.e. obj.__call__()), returning whatever that method returns (which should be a django.http.HttpResponse instance). Thus, at the highest level, view classes may be used identically to view functions.

Since usual instantiation has been modified, you can instantiate a view class with ViewClass._new(request, *args, **kwargs). This might be useful if you need to access functionality defined on another view class (although a separate utility class or mixin is usually a better idea for shared functionality).

Some points to note about this implementation:

• The __new__() method has been overridden to immediately call the instance after creation. You shouldn't need to touch this in a subclass.

• The request processing is carried out in two phases:

  • Initialization: the __init__() method is called on an instance of the view class, with all the arguments passed in from the URLconf (i.e. (self, request, *args, **kwargs)). By default this stores the request, positional and keyword arguments on the instance as self.request, self.args and self.kwargs respectively.

  • Response: the __call__() method is called without any arguments (except self). This should return an instance of django.http.HttpResponse.

• Decorators on instance methods need to be wrapped with django.utils.decorators.method_decorator():

  from somemodule import some_decorator
  from django.utils.decorators import method_decorator
  
  class MyView(View):
  
      @method_decorator(some_decorator)
      def method(self):
          return something()
  

Examples

Simple view definition and invocation:

>>> from djclsview import View
>>> class MyView(View):
...     def __call__(self):
...         print self.request
...         print self.args
...         print self.kwargs

>>> MyView('request', 'arg1', 'arg2', kwarg1='value', kwarg2='value')
request
('arg1', 'arg2')
{'kwarg1': 'value', 'kwarg2': 'value'}

Instantiating a view, sidestepping invocation:

>>> view = MyView._new('request', 'argument', kwarg='value')
>>> view
<__main__.MyView object at 0x...>

Decorating a view with a view decorator:

>>> def auth_required(func):
...     def wrapper(request, *args, **kwargs):
...         assert request['authenticated'], "Unauthenticated!"
...         return func(request, *args, **kwargs)
...     return wrapper

>>> class MyProtectedView(View):
...     def __call__(self):
...         print 'invoking'

>>> MyProtectedView = MyProtectedView._decorate(auth_required)

>>> MyProtectedView({'authenticated': True})
invoking

>>> MyProtectedView({'authenticated': False})
Traceback (most recent call last):
...
AssertionError: Unauthenticated!

Using cls._decorate() is necessary here; just wrapping the class would return the wrapper function (as returned by the decorator). _decorate() wraps __new__() and returns a class.

(Un)license

This is free and unencumbered software released into the public domain.

Anyone is free to copy, modify, publish, use, compile, sell, or distribute this software, either in source code form or as a compiled binary, for any purpose, commercial or non-commercial, and by any means.

In jurisdictions that recognize copyright laws, the author or authors of this software dedicate any and all copyright interest in the software to the public domain. We make this dedication for the benefit of the public at large and to the detriment of our heirs and successors. We intend this dedication to be an overt act of relinquishment in perpetuity of all present and future rights to this software under copyright law.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

For more information, please refer to http://unlicense.org/