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<h1>Source code for django.middleware.gzip</h1><div class="highlight"><pre>
<span></span><span class="kn">import</span> <span class="nn">re</span>
<span class="kn">from</span> <span class="nn">django.utils.cache</span> <span class="k">import</span> <span class="n">patch_vary_headers</span>
<span class="kn">from</span> <span class="nn">django.utils.deprecation</span> <span class="k">import</span> <span class="n">MiddlewareMixin</span>
<span class="kn">from</span> <span class="nn">django.utils.text</span> <span class="k">import</span> <span class="n">compress_sequence</span><span class="p">,</span> <span class="n">compress_string</span>
<span class="n">re_accepts_gzip</span> <span class="o">=</span> <span class="n">re</span><span class="o">.</span><span class="n">compile</span><span class="p">(</span><span class="sa">r</span><span class="s1">'\bgzip\b'</span><span class="p">)</span>
<div class="viewcode-block" id="GZipMiddleware"><a class="viewcode-back" href="../../../ref/middleware.html#django.middleware.gzip.GZipMiddleware">[docs]</a><span class="k">class</span> <span class="nc">GZipMiddleware</span><span class="p">(</span><span class="n">MiddlewareMixin</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> This middleware compresses content if the browser allows gzip compression.</span>
<span class="sd"> It sets the Vary header accordingly, so that caches will base their storage</span>
<span class="sd"> on the Accept-Encoding header.</span>
<span class="sd"> """</span>
<span class="k">def</span> <span class="nf">process_response</span><span class="p">(</span><span class="bp">self</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"># It's not worth attempting to compress really short responses.</span>
<span class="k">if</span> <span class="ow">not</span> <span class="n">response</span><span class="o">.</span><span class="n">streaming</span> <span class="ow">and</span> <span class="nb">len</span><span class="p">(</span><span class="n">response</span><span class="o">.</span><span class="n">content</span><span class="p">)</span> <span class="o"><</span> <span class="mi">200</span><span class="p">:</span>
<span class="k">return</span> <span class="n">response</span>
<span class="c1"># Avoid gzipping if we've already got a content-encoding.</span>
<span class="k">if</span> <span class="n">response</span><span class="o">.</span><span class="n">has_header</span><span class="p">(</span><span class="s1">'Content-Encoding'</span><span class="p">):</span>
<span class="k">return</span> <span class="n">response</span>
<span class="n">patch_vary_headers</span><span class="p">(</span><span class="n">response</span><span class="p">,</span> <span class="p">(</span><span class="s1">'Accept-Encoding'</span><span class="p">,))</span>
<span class="n">ae</span> <span class="o">=</span> <span class="n">request</span><span class="o">.</span><span class="n">META</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="s1">'HTTP_ACCEPT_ENCODING'</span><span class="p">,</span> <span class="s1">''</span><span class="p">)</span>
<span class="k">if</span> <span class="ow">not</span> <span class="n">re_accepts_gzip</span><span class="o">.</span><span class="n">search</span><span class="p">(</span><span class="n">ae</span><span class="p">):</span>
<span class="k">return</span> <span class="n">response</span>
<span class="k">if</span> <span class="n">response</span><span class="o">.</span><span class="n">streaming</span><span class="p">:</span>
<span class="c1"># Delete the `Content-Length` header for streaming content, because</span>
<span class="c1"># we won't know the compressed size until we stream it.</span>
<span class="n">response</span><span class="o">.</span><span class="n">streaming_content</span> <span class="o">=</span> <span class="n">compress_sequence</span><span class="p">(</span><span class="n">response</span><span class="o">.</span><span class="n">streaming_content</span><span class="p">)</span>
<span class="k">del</span> <span class="n">response</span><span class="p">[</span><span class="s1">'Content-Length'</span><span class="p">]</span>
<span class="k">else</span><span class="p">:</span>
<span class="c1"># Return the compressed content only if it's actually shorter.</span>
<span class="n">compressed_content</span> <span class="o">=</span> <span class="n">compress_string</span><span class="p">(</span><span class="n">response</span><span class="o">.</span><span class="n">content</span><span class="p">)</span>
<span class="k">if</span> <span class="nb">len</span><span class="p">(</span><span class="n">compressed_content</span><span class="p">)</span> <span class="o">>=</span> <span class="nb">len</span><span class="p">(</span><span class="n">response</span><span class="o">.</span><span class="n">content</span><span class="p">):</span>
<span class="k">return</span> <span class="n">response</span>
<span class="n">response</span><span class="o">.</span><span class="n">content</span> <span class="o">=</span> <span class="n">compressed_content</span>
<span class="n">response</span><span class="p">[</span><span class="s1">'Content-Length'</span><span class="p">]</span> <span class="o">=</span> <span class="nb">str</span><span class="p">(</span><span class="nb">len</span><span class="p">(</span><span class="n">response</span><span class="o">.</span><span class="n">content</span><span class="p">))</span>
<span class="c1"># If there is a strong ETag, make it weak to fulfill the requirements</span>
<span class="c1"># of RFC 7232 section-2.1 while also allowing conditional request</span>
<span class="c1"># matches on ETags.</span>
<span class="n">etag</span> <span class="o">=</span> <span class="n">response</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="s1">'ETag'</span><span class="p">)</span>
<span class="k">if</span> <span class="n">etag</span> <span class="ow">and</span> <span class="n">etag</span><span class="o">.</span><span class="n">startswith</span><span class="p">(</span><span class="s1">'"'</span><span class="p">):</span>
<span class="n">response</span><span class="p">[</span><span class="s1">'ETag'</span><span class="p">]</span> <span class="o">=</span> <span class="s1">'W/'</span> <span class="o">+</span> <span class="n">etag</span>
<span class="n">response</span><span class="p">[</span><span class="s1">'Content-Encoding'</span><span class="p">]</span> <span class="o">=</span> <span class="s1">'gzip'</span>
<span class="k">return</span> <span class="n">response</span></div>
</pre></div>
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