<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" lang=""> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Writing a custom storage system — Django 1.8.19 documentation</title> <link rel="stylesheet" href="../_static/default.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript"> var DOCUMENTATION_OPTIONS = { URL_ROOT: '../', VERSION: '1.8.19', COLLAPSE_INDEX: false, FILE_SUFFIX: '.html', HAS_SOURCE: true }; </script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/underscore.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <link rel="index" title="Index" href="../genindex.html" /> <link rel="search" title="Search" href="../search.html" /> <link rel="top" title="Django 1.8.19 documentation" href="../contents.html" /> <link rel="up" title="“How-to” guides" href="index.html" /> <link rel="next" title="Deploying Django" href="deployment/index.html" /> <link rel="prev" title="Custom template tags and filters" href="custom-template-tags.html" /> <script type="text/javascript" src="../templatebuiltins.js"></script> <script type="text/javascript"> (function($) { if (!django_template_builtins) { // templatebuiltins.js missing, do nothing. return; } $(document).ready(function() { // Hyperlink Django template tags and filters var base = "../ref/templates/builtins.html"; if (base == "#") { // Special case for builtins.html itself base = ""; } // Tags are keywords, class '.k' $("div.highlight\\-html\\+django span.k").each(function(i, elem) { var tagname = $(elem).text(); if ($.inArray(tagname, django_template_builtins.ttags) != -1) { var fragment = tagname.replace(/_/, '-'); $(elem).html("<a href='" + base + "#" + fragment + "'>" + tagname + "</a>"); } }); // Filters are functions, class '.nf' $("div.highlight\\-html\\+django span.nf").each(function(i, elem) { var filtername = $(elem).text(); if ($.inArray(filtername, django_template_builtins.tfilters) != -1) { var fragment = filtername.replace(/_/, '-'); $(elem).html("<a href='" + base + "#" + fragment + "'>" + filtername + "</a>"); } }); }); })(jQuery); </script> </head> <body role="document"> <div class="document"> <div id="custom-doc" class="yui-t6"> <div id="hd"> <h1><a href="../index.html">Django 1.8.19 documentation</a></h1> <div id="global-nav"> <a title="Home page" href="../index.html">Home</a> | <a title="Table of contents" href="../contents.html">Table of contents</a> | <a title="Global index" href="../genindex.html">Index</a> | <a title="Module index" href="../py-modindex.html">Modules</a> </div> <div class="nav"> « <a href="custom-template-tags.html" title="Custom template tags and filters">previous</a> | <a href="index.html" title="&#8220;How-to&#8221; guides" accesskey="U">up</a> | <a href="deployment/index.html" title="Deploying Django">next</a> »</div> </div> <div id="bd"> <div id="yui-main"> <div class="yui-b"> <div class="yui-g" id="howto-custom-file-storage"> <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 <code class="docutils literal"><span class="pre">django.core.files.storage.Storage</span></code>:</p> <div class="highlight-default"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">django.core.files.storage</span> <span class="k">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 <code class="docutils literal"><span class="pre">django.conf.settings</span></code>:</p> <div class="highlight-default"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">django.conf</span> <span class="k">import</span> <span class="n">settings</span> <span class="kn">from</span> <span class="nn">django.core.files.storage</span> <span class="k">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="kc">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 <a class="reference internal" href="#django.core.files.storage._open" title="django.core.files.storage._open"><code class="xref py py-meth docutils literal"><span class="pre">_open()</span></code></a> and <a class="reference internal" href="#django.core.files.storage._save" title="django.core.files.storage._save"><code class="xref py py-meth docutils literal"><span class="pre">_save()</span></code></a> 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 <code class="docutils literal"><span class="pre">path()</span></code> method.</p> </li> <li><p class="first">Your storage class must be <a class="reference internal" href="../topics/migrations.html#custom-deconstruct-method"><span class="std std-ref">deconstructible</span></a> so it can be serialized when it’s used on a field in a migration. As long as your field has arguments that are themselves <a class="reference internal" href="../topics/migrations.html#migration-serializing"><span class="std std-ref">serializable</span></a>, you can use the <code class="docutils literal"><span class="pre">django.utils.deconstruct.deconstructible</span></code> class decorator for this (that’s what Django uses on FileSystemStorage).</p> </li> </ol> <p>By default, the following methods raise <cite>NotImplementedError</cite> and will typically have to be overridden:</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"><code class="xref py py-meth docutils literal"><span class="pre">Storage.delete()</span></code></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"><code class="xref py py-meth docutils literal"><span class="pre">Storage.exists()</span></code></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"><code class="xref py py-meth docutils literal"><span class="pre">Storage.listdir()</span></code></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"><code class="xref py py-meth docutils literal"><span class="pre">Storage.size()</span></code></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"><code class="xref py py-meth docutils literal"><span class="pre">Storage.url()</span></code></a></li> </ul> <p>Note however that not all these methods are required and may be deliberately omitted. As it happens, it is possible to leave each method unimplemented and still have a working Storage.</p> <p>By way of example, if listing the contents of certain storage backends turns out to be expensive, you might decide not to implement <cite>Storage.listdir</cite>.</p> <p>Another example would be a backend that only handles writing to files. In this case, you would not need to implement any of the above methods.</p> <p>Ultimately, which of these methods are implemented is up to you. Leaving some methods unimplemented will result in a partial (possibly broken) interface.</p> <p>You’ll also usually want to use hooks specifically designed for custom storage objects. These are:</p> <dl class="method"> <dt id="django.core.files.storage._open"> <code class="descname">_open</code>(<em>name</em>, <em>mode='rb'</em>)<a class="headerlink" href="#django.core.files.storage._open" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p><strong>Required</strong>.</p> <p>Called by <code class="docutils literal"><span class="pre">Storage.open()</span></code>, this is the actual mechanism the storage class uses to open the file. This must return a <code class="docutils literal"><span class="pre">File</span></code> object, though in most cases, you’ll want to return some subclass here that implements logic specific to the backend storage system.</p> <dl class="method"> <dt id="django.core.files.storage._save"> <code class="descname">_save</code>(<em>name</em>, <em>content</em>)<a class="headerlink" href="#django.core.files.storage._save" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Called by <code class="docutils literal"><span class="pre">Storage.save()</span></code>. The <code class="docutils literal"><span class="pre">name</span></code> will already have gone through <code class="docutils literal"><span class="pre">get_valid_name()</span></code> and <code class="docutils literal"><span class="pre">get_available_name()</span></code>, and the <code class="docutils literal"><span class="pre">content</span></code> will be a <code class="docutils literal"><span class="pre">File</span></code> object itself.</p> <p>Should return the actual name of name of the file saved (usually the <code class="docutils literal"><span class="pre">name</span></code> passed in, but if the storage needs to change the file name return the new name instead).</p> <dl class="method"> <dt id="django.core.files.storage.get_valid_name"> <code class="descname">get_valid_name</code>(<em>name</em>)<a class="headerlink" href="#django.core.files.storage.get_valid_name" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Returns a filename suitable for use with the underlying storage system. The <code class="docutils literal"><span class="pre">name</span></code> 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 <code class="docutils literal"><span class="pre">Storage</span></code> retains only alpha-numeric characters, periods and underscores from the original filename, removing everything else.</p> <dl class="method"> <dt id="django.core.files.storage.get_available_name"> <code class="descname">get_available_name</code>(<em>name</em>, <em>max_length=None</em>)<a class="headerlink" href="#django.core.files.storage.get_available_name" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <p>Returns a filename that is available in the storage mechanism, possibly taking the provided filename into account. The <code class="docutils literal"><span class="pre">name</span></code> argument passed to this method will have already cleaned to a filename valid for the storage system, according to the <code class="docutils literal"><span class="pre">get_valid_name()</span></code> method described above.</p> <p>The length of the filename will not exceed <code class="docutils literal"><span class="pre">max_length</span></code>, if provided. If a free unique filename cannot be found, a <a class="reference internal" href="../ref/exceptions.html#django.core.exceptions.SuspiciousOperation" title="django.core.exceptions.SuspiciousOperation"><code class="xref py py-exc docutils literal"><span class="pre">SuspiciousFileOperation</span></code></a> exception is raised.</p> <p>If a file with <code class="docutils literal"><span class="pre">name</span></code> already exists, an underscore plus a random 7 character alphanumeric string is appended to the filename before the extension.</p> <div class="versionchanged"> <span class="title">Changed in Django 1.7:</span> <p>Previously, an underscore followed by a number (e.g. <code class="docutils literal"><span class="pre">"_1"</span></code>, <code class="docutils literal"><span class="pre">"_2"</span></code>, etc.) was appended to the filename until an available name in the destination directory was found. A malicious user could exploit this deterministic algorithm to create a denial-of-service attack. This change was also made in Django 1.6.6, 1.5.9, and 1.4.14.</p> </div> <div class="versionchanged"> <span class="title">Changed in Django 1.8:</span> <p>The <code class="docutils literal"><span class="pre">max_length</span></code> argument was added.</p> </div> </div> </div> </div> </div> <div class="yui-b" id="sidebar"> <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> <div class="sphinxsidebarwrapper"> <h3>Browse</h3> <ul> <li>Prev: <a href="custom-template-tags.html">Custom template tags and filters</a></li> <li>Next: <a href="deployment/index.html">Deploying Django</a></li> </ul> <h3>You are here:</h3> <ul> <li> <a href="../index.html">Django 1.8.19 documentation</a> <ul><li><a href="index.html">“How-to” guides</a> <ul><li>Writing a custom storage system</li></ul> </li></ul> </li> </ul> <div role="note" aria-label="source link"> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../_sources/howto/custom-file-storage.txt" rel="nofollow">Show Source</a></li> </ul> </div> <div id="searchbox" style="display: none" role="search"> <h3>Quick search</h3> <form class="search" action="../search.html" method="get"> <div><input type="text" name="q" /></div> <div><input type="submit" value="Go" /></div> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> <script type="text/javascript">$('#searchbox').show(0);</script> </div> </div> <h3>Last update:</h3> <p class="topless">Jan 06, 2019</p> </div> </div> <div id="ft"> <div class="nav"> « <a href="custom-template-tags.html" title="Custom template tags and filters">previous</a> | <a href="index.html" title="&#8220;How-to&#8221; guides" accesskey="U">up</a> | <a href="deployment/index.html" title="Deploying Django">next</a> »</div> </div> </div> <div class="clearer"></div> </div> </body> </html>