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1 """ |
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2 Decorator for views that tries getting the page from the cache and |
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3 populates the cache if the page isn't in the cache yet. |
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4 |
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5 The cache is keyed by the URL and some data from the headers. Additionally |
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6 there is the key prefix that is used to distinguish different cache areas |
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7 in a multi-site setup. You could use the sites.get_current().domain, for |
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8 example, as that is unique across a Django project. |
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9 |
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10 Additionally, all headers from the response's Vary header will be taken into |
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11 account on caching -- just like the middleware does. |
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12 """ |
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13 |
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14 try: |
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15 from functools import wraps |
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16 except ImportError: |
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17 from django.utils.functional import wraps # Python 2.4 fallback. |
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18 |
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19 from django.utils.decorators import decorator_from_middleware_with_args, available_attrs |
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20 from django.utils.cache import patch_cache_control, add_never_cache_headers |
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21 from django.middleware.cache import CacheMiddleware |
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22 |
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23 |
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24 def cache_page(*args, **kwargs): |
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25 # We need backwards compatibility with code which spells it this way: |
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26 # def my_view(): pass |
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27 # my_view = cache_page(my_view, 123) |
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28 # and this way: |
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29 # my_view = cache_page(123)(my_view) |
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30 # and this: |
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31 # my_view = cache_page(my_view, 123, key_prefix="foo") |
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32 # and this: |
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33 # my_view = cache_page(123, key_prefix="foo")(my_view) |
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34 # and possibly this way (?): |
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35 # my_view = cache_page(123, my_view) |
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36 |
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37 # We also add some asserts to give better error messages in case people are |
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38 # using other ways to call cache_page that no longer work. |
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39 key_prefix = kwargs.pop('key_prefix', None) |
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40 assert not kwargs, "The only keyword argument accepted is key_prefix" |
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41 if len(args) > 1: |
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42 assert len(args) == 2, "cache_page accepts at most 2 arguments" |
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43 if callable(args[0]): |
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44 return decorator_from_middleware_with_args(CacheMiddleware)(cache_timeout=args[1], key_prefix=key_prefix)(args[0]) |
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45 elif callable(args[1]): |
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46 return decorator_from_middleware_with_args(CacheMiddleware)(cache_timeout=args[0], key_prefix=key_prefix)(args[1]) |
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47 else: |
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48 assert False, "cache_page must be passed either a single argument (timeout) or a view function and a timeout" |
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49 else: |
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50 return decorator_from_middleware_with_args(CacheMiddleware)(cache_timeout=args[0], key_prefix=key_prefix) |
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51 |
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52 |
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53 def cache_control(**kwargs): |
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54 def _cache_controller(viewfunc): |
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55 def _cache_controlled(request, *args, **kw): |
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56 response = viewfunc(request, *args, **kw) |
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57 patch_cache_control(response, **kwargs) |
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58 return response |
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59 return wraps(viewfunc, assigned=available_attrs(viewfunc))(_cache_controlled) |
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60 return _cache_controller |
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61 |
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62 |
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63 def never_cache(view_func): |
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64 """ |
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65 Decorator that adds headers to a response so that it will |
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66 never be cached. |
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67 """ |
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68 def _wrapped_view_func(request, *args, **kwargs): |
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69 response = view_func(request, *args, **kwargs) |
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70 add_never_cache_headers(response) |
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71 return response |
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72 return wraps(view_func, assigned=available_attrs(view_func))(_wrapped_view_func) |