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<div class="section" id="s-writing-a-custom-storage-system">
<span id="writing-a-custom-storage-system"></span><h1>Writing a custom storage system<a class="headerlink" href="#writing-a-custom-storage-system" title="Permalink to this headline">¶</a></h1>
<p>If you need to provide custom file storage – a common example is storing files
on some remote system – you can do so by defining a custom storage class.
You’ll need to follow these steps:</p>
<ol class="arabic">
<li><p class="first">Your custom storage system must be a subclass of
<tt class="docutils literal"><span class="pre">django.core.files.storage.Storage</span></tt>:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">django.core.files.storage</span> <span class="kn">import</span> <span class="n">Storage</span>
<span class="k">class</span> <span class="nc">MyStorage</span><span class="p">(</span><span class="n">Storage</span><span class="p">):</span>
<span class="o">...</span>
</pre></div>
</div>
</li>
<li><p class="first">Django must be able to instantiate your storage system without any arguments.
This means that any settings should be taken from <tt class="docutils literal"><span class="pre">django.conf.settings</span></tt>:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">django.conf</span> <span class="kn">import</span> <span class="n">settings</span>
<span class="kn">from</span> <span class="nn">django.core.files.storage</span> <span class="kn">import</span> <span class="n">Storage</span>
<span class="k">class</span> <span class="nc">MyStorage</span><span class="p">(</span><span class="n">Storage</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">option</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
<span class="k">if</span> <span class="ow">not</span> <span class="n">option</span><span class="p">:</span>
<span class="n">option</span> <span class="o">=</span> <span class="n">settings</span><span class="o">.</span><span class="n">CUSTOM_STORAGE_OPTIONS</span>
<span class="o">...</span>
</pre></div>
</div>
</li>
<li><p class="first">Your storage class must implement the <tt class="docutils literal"><span class="pre">_open()</span></tt> and <tt class="docutils literal"><span class="pre">_save()</span></tt> methods,
along with any other methods appropriate to your storage class. See below for
more on these methods.</p>
<p>In addition, if your class provides local file storage, it must override
the <tt class="docutils literal"><span class="pre">path()</span></tt> method.</p>
</li>
</ol>
<p>Your custom storage system may override any of the storage methods explained in
<a class="reference internal" href="../ref/files/storage.html"><em>File storage API</em></a>, but you <strong>must</strong> implement the following methods:</p>
<ul class="simple">
<li><a class="reference internal" href="../ref/files/storage.html#django.core.files.storage.Storage.delete" title="django.core.files.storage.Storage.delete"><tt class="xref py py-meth docutils literal"><span class="pre">Storage.delete()</span></tt></a></li>
<li><a class="reference internal" href="../ref/files/storage.html#django.core.files.storage.Storage.exists" title="django.core.files.storage.Storage.exists"><tt class="xref py py-meth docutils literal"><span class="pre">Storage.exists()</span></tt></a></li>
<li><a class="reference internal" href="../ref/files/storage.html#django.core.files.storage.Storage.listdir" title="django.core.files.storage.Storage.listdir"><tt class="xref py py-meth docutils literal"><span class="pre">Storage.listdir()</span></tt></a></li>
<li><a class="reference internal" href="../ref/files/storage.html#django.core.files.storage.Storage.size" title="django.core.files.storage.Storage.size"><tt class="xref py py-meth docutils literal"><span class="pre">Storage.size()</span></tt></a></li>
<li><a class="reference internal" href="../ref/files/storage.html#django.core.files.storage.Storage.url" title="django.core.files.storage.Storage.url"><tt class="xref py py-meth docutils literal"><span class="pre">Storage.url()</span></tt></a></li>
</ul>
<p>You’ll also usually want to use hooks specifically designed for custom storage
objects. These are:</p>
<div class="section" id="s-open-name-mode-rb">
<span id="open-name-mode-rb"></span><h2><tt class="docutils literal"><span class="pre">_open(name,</span> <span class="pre">mode='rb')</span></tt><a class="headerlink" href="#open-name-mode-rb" title="Permalink to this headline">¶</a></h2>
<p><strong>Required</strong>.</p>
<p>Called by <tt class="docutils literal"><span class="pre">Storage.open()</span></tt>, this is the actual mechanism the storage class
uses to open the file. This must return a <tt class="docutils literal"><span class="pre">File</span></tt> object, though in most cases,
you’ll want to return some subclass here that implements logic specific to the
backend storage system.</p>
</div>
<div class="section" id="s-save-name-content">
<span id="save-name-content"></span><h2><tt class="docutils literal"><span class="pre">_save(name,</span> <span class="pre">content)</span></tt><a class="headerlink" href="#save-name-content" title="Permalink to this headline">¶</a></h2>
<p>Called by <tt class="docutils literal"><span class="pre">Storage.save()</span></tt>. The <tt class="docutils literal"><span class="pre">name</span></tt> will already have gone through
<tt class="docutils literal"><span class="pre">get_valid_name()</span></tt> and <tt class="docutils literal"><span class="pre">get_available_name()</span></tt>, and the <tt class="docutils literal"><span class="pre">content</span></tt> will be a
<tt class="docutils literal"><span class="pre">File</span></tt> object itself.</p>
<p>Should return the actual name of name of the file saved (usually the <tt class="docutils literal"><span class="pre">name</span></tt>
passed in, but if the storage needs to change the file name return the new name
instead).</p>
</div>
<div class="section" id="s-get-valid-name-name">
<span id="get-valid-name-name"></span><h2><tt class="docutils literal"><span class="pre">get_valid_name(name)</span></tt><a class="headerlink" href="#get-valid-name-name" title="Permalink to this headline">¶</a></h2>
<p>Returns a filename suitable for use with the underlying storage system. The
<tt class="docutils literal"><span class="pre">name</span></tt> argument passed to this method is the original filename sent to the
server, after having any path information removed. Override this to customize
how non-standard characters are converted to safe filenames.</p>
<p>The code provided on <tt class="docutils literal"><span class="pre">Storage</span></tt> retains only alpha-numeric characters, periods
and underscores from the original filename, removing everything else.</p>
</div>
<div class="section" id="s-get-available-name-name">
<span id="get-available-name-name"></span><h2><tt class="docutils literal"><span class="pre">get_available_name(name)</span></tt><a class="headerlink" href="#get-available-name-name" title="Permalink to this headline">¶</a></h2>
<p>Returns a filename that is available in the storage mechanism, possibly taking
the provided filename into account. The <tt class="docutils literal"><span class="pre">name</span></tt> argument passed to this method
will have already cleaned to a filename valid for the storage system, according
to the <tt class="docutils literal"><span class="pre">get_valid_name()</span></tt> method described above.</p>
<p>The code provided on <tt class="docutils literal"><span class="pre">Storage</span></tt> simply appends <tt class="docutils literal"><span class="pre">"_1"</span></tt>, <tt class="docutils literal"><span class="pre">"_2"</span></tt>, etc. to the
filename until it finds one that’s available in the destination directory.</p>
</div>
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<ul>
<li><a class="reference internal" href="#">Writing a custom storage system</a><ul>
<li><a class="reference internal" href="#open-name-mode-rb"><tt class="docutils literal"><span class="pre">_open(name,</span> <span class="pre">mode='rb')</span></tt></a></li>
<li><a class="reference internal" href="#save-name-content"><tt class="docutils literal"><span class="pre">_save(name,</span> <span class="pre">content)</span></tt></a></li>
<li><a class="reference internal" href="#get-valid-name-name"><tt class="docutils literal"><span class="pre">get_valid_name(name)</span></tt></a></li>
<li><a class="reference internal" href="#get-available-name-name"><tt class="docutils literal"><span class="pre">get_available_name(name)</span></tt></a></li>
</ul>
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