django/utils/decorators.py

   1 "Functions that help with dynamically creating decorators for views."
   2
   3 import types
   4 try:
   5     from functools import wraps
   6 except ImportError:
   7     from django.utils.functional import wraps  # Python 2.3, 2.4 fallback.
   8
   9 def decorator_from_middleware(middleware_class):
  10     """
  11     Given a middleware class (not an instance), returns a view decorator. This
  12     lets you use middleware functionality on a per-view basis.
  13     """
  14     def _decorator_from_middleware(*args, **kwargs):
  15         # For historical reasons, these "decorators" are also called as
  16         # dec(func, *args) instead of dec(*args)(func). We handle both forms
  17         # for backwards compatibility.
  18         has_func = True
  19         try:
  20             view_func = kwargs.pop('view_func')
  21         except KeyError:
  22             if len(args):
  23                 view_func, args = args[0], args[1:]
  24             else:
  25                 has_func = False
  26         if not (has_func and isinstance(view_func, types.FunctionType)):
  27             # We are being called as a decorator.
  28             if has_func:
  29                 args = (view_func,) + args
  30             middleware = middleware_class(*args, **kwargs)
  31
  32             def decorator_func(fn):
  33                 return _decorator_from_middleware(fn, *args, **kwargs)
  34             return decorator_func
  35
  36         middleware = middleware_class(*args, **kwargs)
  37
  38         def _wrapped_view(request, *args, **kwargs):
  39             if hasattr(middleware, 'process_request'):
  40                 result = middleware.process_request(request)
  41                 if result is not None:
  42                     return result
  43             if hasattr(middleware, 'process_view'):
  44                 result = middleware.process_view(request, view_func, args, kwargs)
  45                 if result is not None:
  46                     return result
  47             try:
  48                 response = view_func(request, *args, **kwargs)
  49             except Exception, e:
  50                 if hasattr(middleware, 'process_exception'):
  51                     result = middleware.process_exception(request, e)
  52                     if result is not None:
  53                         return result
  54                 raise
  55             if hasattr(middleware, 'process_response'):
  56                 result = middleware.process_response(request, response)
  57                 if result is not None:
  58                     return result
  59             return response
  60         return wraps(view_func)(_wrapped_view)
  61     return _decorator_from_middleware