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<h1>Source code for django.utils.decorators</h1><div class="highlight"><pre>
<span></span><span class="s2">"Functions that help with dynamically creating decorators for views."</span>
<span class="k">try</span><span class="p">:</span>
<span class="kn">from</span> <span class="nn">contextlib</span> <span class="k">import</span> <span class="n">ContextDecorator</span>
<span class="k">except</span> <span class="ne">ImportError</span><span class="p">:</span>
<span class="n">ContextDecorator</span> <span class="o">=</span> <span class="kc">None</span>
<span class="kn">from</span> <span class="nn">functools</span> <span class="k">import</span> <span class="n">WRAPPER_ASSIGNMENTS</span><span class="p">,</span> <span class="n">update_wrapper</span><span class="p">,</span> <span class="n">wraps</span>
<span class="kn">from</span> <span class="nn">django.utils</span> <span class="k">import</span> <span class="n">six</span>
<span class="k">class</span> <span class="nc">classonlymethod</span><span class="p">(</span><span class="nb">classmethod</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">__get__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">instance</span><span class="p">,</span> <span class="n">owner</span><span class="p">):</span>
<span class="k">if</span> <span class="n">instance</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">AttributeError</span><span class="p">(</span><span class="s2">"This method is available only on the class, not on instances."</span><span class="p">)</span>
<span class="k">return</span> <span class="nb">super</span><span class="p">(</span><span class="n">classonlymethod</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">__get__</span><span class="p">(</span><span class="n">instance</span><span class="p">,</span> <span class="n">owner</span><span class="p">)</span>
<div class="viewcode-block" id="method_decorator"><a class="viewcode-back" href="../../../ref/utils.html#django.utils.decorators.method_decorator">[docs]</a><span class="k">def</span> <span class="nf">method_decorator</span><span class="p">(</span><span class="n">decorator</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Converts a function decorator into a method decorator</span>
<span class="sd"> """</span>
<span class="c1"># 'func' is a function at the time it is passed to _dec, but will eventually</span>
<span class="c1"># be a method of the class it is defined on.</span>
<span class="k">def</span> <span class="nf">_dec</span><span class="p">(</span><span class="n">func</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">_wrapper</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
<span class="nd">@decorator</span>
<span class="k">def</span> <span class="nf">bound_func</span><span class="p">(</span><span class="o">*</span><span class="n">args2</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs2</span><span class="p">):</span>
<span class="k">return</span> <span class="n">func</span><span class="o">.</span><span class="n">__get__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="nb">type</span><span class="p">(</span><span class="bp">self</span><span class="p">))(</span><span class="o">*</span><span class="n">args2</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs2</span><span class="p">)</span>
<span class="c1"># bound_func has the signature that 'decorator' expects i.e. no</span>
<span class="c1"># 'self' argument, but it is a closure over self so it can call</span>
<span class="c1"># 'func' correctly.</span>
<span class="k">return</span> <span class="n">bound_func</span><span class="p">(</span><span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">)</span>
<span class="c1"># In case 'decorator' adds attributes to the function it decorates, we</span>
<span class="c1"># want to copy those. We don't have access to bound_func in this scope,</span>
<span class="c1"># but we can cheat by using it on a dummy function.</span>
<span class="nd">@decorator</span>
<span class="k">def</span> <span class="nf">dummy</span><span class="p">(</span><span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
<span class="k">pass</span>
<span class="n">update_wrapper</span><span class="p">(</span><span class="n">_wrapper</span><span class="p">,</span> <span class="n">dummy</span><span class="p">)</span>
<span class="c1"># Need to preserve any existing attributes of 'func', including the name.</span>
<span class="n">update_wrapper</span><span class="p">(</span><span class="n">_wrapper</span><span class="p">,</span> <span class="n">func</span><span class="p">)</span>
<span class="k">return</span> <span class="n">_wrapper</span>
<span class="n">update_wrapper</span><span class="p">(</span><span class="n">_dec</span><span class="p">,</span> <span class="n">decorator</span><span class="p">,</span> <span class="n">assigned</span><span class="o">=</span><span class="n">available_attrs</span><span class="p">(</span><span class="n">decorator</span><span class="p">))</span>
<span class="c1"># Change the name to aid debugging.</span>
<span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">decorator</span><span class="p">,</span> <span class="s1">'__name__'</span><span class="p">):</span>
<span class="n">_dec</span><span class="o">.</span><span class="n">__name__</span> <span class="o">=</span> <span class="s1">'method_decorator(</span><span class="si">%s</span><span class="s1">)'</span> <span class="o">%</span> <span class="n">decorator</span><span class="o">.</span><span class="n">__name__</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">_dec</span><span class="o">.</span><span class="n">__name__</span> <span class="o">=</span> <span class="s1">'method_decorator(</span><span class="si">%s</span><span class="s1">)'</span> <span class="o">%</span> <span class="n">decorator</span><span class="o">.</span><span class="n">__class__</span><span class="o">.</span><span class="n">__name__</span>
<span class="k">return</span> <span class="n">_dec</span></div>
<div class="viewcode-block" id="decorator_from_middleware_with_args"><a class="viewcode-back" href="../../../ref/utils.html#django.utils.decorators.decorator_from_middleware_with_args">[docs]</a><span class="k">def</span> <span class="nf">decorator_from_middleware_with_args</span><span class="p">(</span><span class="n">middleware_class</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Like decorator_from_middleware, but returns a function</span>
<span class="sd"> that accepts the arguments to be passed to the middleware_class.</span>
<span class="sd"> Use like::</span>
<span class="sd"> cache_page = decorator_from_middleware_with_args(CacheMiddleware)</span>
<span class="sd"> # ...</span>
<span class="sd"> @cache_page(3600)</span>
<span class="sd"> def my_view(request):</span>
<span class="sd"> # ...</span>
<span class="sd"> """</span>
<span class="k">return</span> <span class="n">make_middleware_decorator</span><span class="p">(</span><span class="n">middleware_class</span><span class="p">)</span></div>
<div class="viewcode-block" id="decorator_from_middleware"><a class="viewcode-back" href="../../../ref/utils.html#django.utils.decorators.decorator_from_middleware">[docs]</a><span class="k">def</span> <span class="nf">decorator_from_middleware</span><span class="p">(</span><span class="n">middleware_class</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Given a middleware class (not an instance), returns a view decorator. This</span>
<span class="sd"> lets you use middleware functionality on a per-view basis. The middleware</span>
<span class="sd"> is created with no params passed.</span>
<span class="sd"> """</span>
<span class="k">return</span> <span class="n">make_middleware_decorator</span><span class="p">(</span><span class="n">middleware_class</span><span class="p">)()</span></div>
<span class="k">def</span> <span class="nf">available_attrs</span><span class="p">(</span><span class="n">fn</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Return the list of functools-wrappable attributes on a callable.</span>
<span class="sd"> This is required as a workaround for http://bugs.python.org/issue3445</span>
<span class="sd"> under Python 2.</span>
<span class="sd"> """</span>
<span class="k">if</span> <span class="n">six</span><span class="o">.</span><span class="n">PY3</span><span class="p">:</span>
<span class="k">return</span> <span class="n">WRAPPER_ASSIGNMENTS</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">return</span> <span class="nb">tuple</span><span class="p">(</span><span class="n">a</span> <span class="k">for</span> <span class="n">a</span> <span class="ow">in</span> <span class="n">WRAPPER_ASSIGNMENTS</span> <span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">fn</span><span class="p">,</span> <span class="n">a</span><span class="p">))</span>
<span class="k">def</span> <span class="nf">make_middleware_decorator</span><span class="p">(</span><span class="n">middleware_class</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">_make_decorator</span><span class="p">(</span><span class="o">*</span><span class="n">m_args</span><span class="p">,</span> <span class="o">**</span><span class="n">m_kwargs</span><span class="p">):</span>
<span class="n">middleware</span> <span class="o">=</span> <span class="n">middleware_class</span><span class="p">(</span><span class="o">*</span><span class="n">m_args</span><span class="p">,</span> <span class="o">**</span><span class="n">m_kwargs</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">_decorator</span><span class="p">(</span><span class="n">view_func</span><span class="p">):</span>
<span class="nd">@wraps</span><span class="p">(</span><span class="n">view_func</span><span class="p">,</span> <span class="n">assigned</span><span class="o">=</span><span class="n">available_attrs</span><span class="p">(</span><span class="n">view_func</span><span class="p">))</span>
<span class="k">def</span> <span class="nf">_wrapped_view</span><span class="p">(</span><span class="n">request</span><span class="p">,</span> <span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
<span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">middleware</span><span class="p">,</span> <span class="s1">'process_request'</span><span class="p">):</span>
<span class="n">result</span> <span class="o">=</span> <span class="n">middleware</span><span class="o">.</span><span class="n">process_request</span><span class="p">(</span><span class="n">request</span><span class="p">)</span>
<span class="k">if</span> <span class="n">result</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span>
<span class="k">return</span> <span class="n">result</span>
<span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">middleware</span><span class="p">,</span> <span class="s1">'process_view'</span><span class="p">):</span>
<span class="n">result</span> <span class="o">=</span> <span class="n">middleware</span><span class="o">.</span><span class="n">process_view</span><span class="p">(</span><span class="n">request</span><span class="p">,</span> <span class="n">view_func</span><span class="p">,</span> <span class="n">args</span><span class="p">,</span> <span class="n">kwargs</span><span class="p">)</span>
<span class="k">if</span> <span class="n">result</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span>
<span class="k">return</span> <span class="n">result</span>
<span class="k">try</span><span class="p">:</span>
<span class="n">response</span> <span class="o">=</span> <span class="n">view_func</span><span class="p">(</span><span class="n">request</span><span class="p">,</span> <span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">)</span>
<span class="k">except</span> <span class="ne">Exception</span> <span class="k">as</span> <span class="n">e</span><span class="p">:</span>
<span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">middleware</span><span class="p">,</span> <span class="s1">'process_exception'</span><span class="p">):</span>
<span class="n">result</span> <span class="o">=</span> <span class="n">middleware</span><span class="o">.</span><span class="n">process_exception</span><span class="p">(</span><span class="n">request</span><span class="p">,</span> <span class="n">e</span><span class="p">)</span>
<span class="k">if</span> <span class="n">result</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span>
<span class="k">return</span> <span class="n">result</span>
<span class="k">raise</span>
<span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">response</span><span class="p">,</span> <span class="s1">'render'</span><span class="p">)</span> <span class="ow">and</span> <span class="n">callable</span><span class="p">(</span><span class="n">response</span><span class="o">.</span><span class="n">render</span><span class="p">):</span>
<span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">middleware</span><span class="p">,</span> <span class="s1">'process_template_response'</span><span class="p">):</span>
<span class="n">response</span> <span class="o">=</span> <span class="n">middleware</span><span class="o">.</span><span class="n">process_template_response</span><span class="p">(</span><span class="n">request</span><span class="p">,</span> <span class="n">response</span><span class="p">)</span>
<span class="c1"># Defer running of process_response until after the template</span>
<span class="c1"># has been rendered:</span>
<span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">middleware</span><span class="p">,</span> <span class="s1">'process_response'</span><span class="p">):</span>
<span class="n">callback</span> <span class="o">=</span> <span class="k">lambda</span> <span class="n">response</span><span class="p">:</span> <span class="n">middleware</span><span class="o">.</span><span class="n">process_response</span><span class="p">(</span><span class="n">request</span><span class="p">,</span> <span class="n">response</span><span class="p">)</span>
<span class="n">response</span><span class="o">.</span><span class="n">add_post_render_callback</span><span class="p">(</span><span class="n">callback</span><span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">middleware</span><span class="p">,</span> <span class="s1">'process_response'</span><span class="p">):</span>
<span class="k">return</span> <span class="n">middleware</span><span class="o">.</span><span class="n">process_response</span><span class="p">(</span><span class="n">request</span><span class="p">,</span> <span class="n">response</span><span class="p">)</span>
<span class="k">return</span> <span class="n">response</span>
<span class="k">return</span> <span class="n">_wrapped_view</span>
<span class="k">return</span> <span class="n">_decorator</span>
<span class="k">return</span> <span class="n">_make_decorator</span>
<span class="k">if</span> <span class="n">ContextDecorator</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
<span class="c1"># ContextDecorator was introduced in Python 3.2</span>
<span class="c1"># See https://docs.python.org/3/library/contextlib.html#contextlib.ContextDecorator</span>
<span class="k">class</span> <span class="nc">ContextDecorator</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> A base class that enables a context manager to also be used as a decorator.</span>
<span class="sd"> """</span>
<span class="k">def</span> <span class="nf">__call__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">func</span><span class="p">):</span>
<span class="nd">@wraps</span><span class="p">(</span><span class="n">func</span><span class="p">,</span> <span class="n">assigned</span><span class="o">=</span><span class="n">available_attrs</span><span class="p">(</span><span class="n">func</span><span class="p">))</span>
<span class="k">def</span> <span class="nf">inner</span><span class="p">(</span><span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
<span class="k">with</span> <span class="bp">self</span><span class="p">:</span>
<span class="k">return</span> <span class="n">func</span><span class="p">(</span><span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">)</span>
<span class="k">return</span> <span class="n">inner</span>
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