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<li class="nav-item nav-item-this"><a href="">Class-based Views</a></li>
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<section id="class-based-views">
<h1>Class-based Views<a class="headerlink" href="#class-based-views" title="Link to this heading"></a></h1>
<p>This page introduces using the <a class="reference internal" href="api.html#flask.views.View" title="flask.views.View"><code class="xref py py-class docutils literal notranslate"><span class="pre">View</span></code></a> and <a class="reference internal" href="api.html#flask.views.MethodView" title="flask.views.MethodView"><code class="xref py py-class docutils literal notranslate"><span class="pre">MethodView</span></code></a>
classes to write class-based views.</p>
<p>A class-based view is a class that acts as a view function. Because it
is a class, different instances of the class can be created with
different arguments, to change the behavior of the view. This is also
known as generic, reusable, or pluggable views.</p>
<p>An example of where this is useful is defining a class that creates an
API based on the database model it is initialized with.</p>
<p>For more complex API behavior and customization, look into the various
API extensions for Flask.</p>
<section id="basic-reusable-view">
<h2>Basic Reusable View<a class="headerlink" href="#basic-reusable-view" title="Link to this heading"></a></h2>
<p>Let’s walk through an example converting a view function to a view
class. We start with a view function that queries a list of users then
renders a template to show the list.</p>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="nd">@app</span><span class="o">.</span><span class="n">route</span><span class="p">(</span><span class="s2">&quot;/users/&quot;</span><span class="p">)</span>
<span class="k">def</span><span class="w"> </span><span class="nf">user_list</span><span class="p">():</span>
<span class="n">users</span> <span class="o">=</span> <span class="n">User</span><span class="o">.</span><span class="n">query</span><span class="o">.</span><span class="n">all</span><span class="p">()</span>
<span class="k">return</span> <span class="n">render_template</span><span class="p">(</span><span class="s2">&quot;users.html&quot;</span><span class="p">,</span> <span class="n">users</span><span class="o">=</span><span class="n">users</span><span class="p">)</span>
</pre></div>
</div>
<p>This works for the user model, but let’s say you also had more models
that needed list pages. You’d need to write another view function for
each model, even though the only thing that would change is the model
and template name.</p>
<p>Instead, you can write a <a class="reference internal" href="api.html#flask.views.View" title="flask.views.View"><code class="xref py py-class docutils literal notranslate"><span class="pre">View</span></code></a> subclass that will query a model
and render a template. As the first step, we’ll convert the view to a
class without any customization.</p>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="kn">from</span><span class="w"> </span><span class="nn">flask.views</span><span class="w"> </span><span class="kn">import</span> <span class="n">View</span>
<span class="k">class</span><span class="w"> </span><span class="nc">UserList</span><span class="p">(</span><span class="n">View</span><span class="p">):</span>
<span class="k">def</span><span class="w"> </span><span class="nf">dispatch_request</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">users</span> <span class="o">=</span> <span class="n">User</span><span class="o">.</span><span class="n">query</span><span class="o">.</span><span class="n">all</span><span class="p">()</span>
<span class="k">return</span> <span class="n">render_template</span><span class="p">(</span><span class="s2">&quot;users.html&quot;</span><span class="p">,</span> <span class="n">objects</span><span class="o">=</span><span class="n">users</span><span class="p">)</span>
<span class="n">app</span><span class="o">.</span><span class="n">add_url_rule</span><span class="p">(</span><span class="s2">&quot;/users/&quot;</span><span class="p">,</span> <span class="n">view_func</span><span class="o">=</span><span class="n">UserList</span><span class="o">.</span><span class="n">as_view</span><span class="p">(</span><span class="s2">&quot;user_list&quot;</span><span class="p">))</span>
</pre></div>
</div>
<p>The <a class="reference internal" href="api.html#flask.views.View.dispatch_request" title="flask.views.View.dispatch_request"><code class="xref py py-meth docutils literal notranslate"><span class="pre">View.dispatch_request()</span></code></a> method is the equivalent of the view
function. Calling <a class="reference internal" href="api.html#flask.views.View.as_view" title="flask.views.View.as_view"><code class="xref py py-meth docutils literal notranslate"><span class="pre">View.as_view()</span></code></a> method will create a view
function that can be registered on the app with its
<a class="reference internal" href="api.html#flask.Flask.add_url_rule" title="flask.Flask.add_url_rule"><code class="xref py py-meth docutils literal notranslate"><span class="pre">add_url_rule()</span></code></a> method. The first argument to
<code class="docutils literal notranslate"><span class="pre">as_view</span></code> is the name to use to refer to the view with
<a class="reference internal" href="api.html#flask.url_for" title="flask.url_for"><code class="xref py py-func docutils literal notranslate"><span class="pre">url_for()</span></code></a>.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>You can’t decorate the class with <code class="docutils literal notranslate"><span class="pre">&#64;app.route()</span></code> the way you’d
do with a basic view function.</p>
</div>
<p>Next, we need to be able to register the same view class for different
models and templates, to make it more useful than the original function.
The class will take two arguments, the model and template, and store
them on <code class="docutils literal notranslate"><span class="pre">self</span></code>. Then <code class="docutils literal notranslate"><span class="pre">dispatch_request</span></code> can reference these instead
of hard-coded values.</p>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="k">class</span><span class="w"> </span><span class="nc">ListView</span><span class="p">(</span><span class="n">View</span><span class="p">):</span>
<span class="k">def</span><span class="w"> </span><span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">model</span><span class="p">,</span> <span class="n">template</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">model</span> <span class="o">=</span> <span class="n">model</span>
<span class="bp">self</span><span class="o">.</span><span class="n">template</span> <span class="o">=</span> <span class="n">template</span>
<span class="k">def</span><span class="w"> </span><span class="nf">dispatch_request</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">items</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">model</span><span class="o">.</span><span class="n">query</span><span class="o">.</span><span class="n">all</span><span class="p">()</span>
<span class="k">return</span> <span class="n">render_template</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">template</span><span class="p">,</span> <span class="n">items</span><span class="o">=</span><span class="n">items</span><span class="p">)</span>
</pre></div>
</div>
<p>Remember, we create the view function with <code class="docutils literal notranslate"><span class="pre">View.as_view()</span></code> instead of
creating the class directly. Any extra arguments passed to <code class="docutils literal notranslate"><span class="pre">as_view</span></code>
are then passed when creating the class. Now we can register the same
view to handle multiple models.</p>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="n">app</span><span class="o">.</span><span class="n">add_url_rule</span><span class="p">(</span>
<span class="s2">&quot;/users/&quot;</span><span class="p">,</span>
<span class="n">view_func</span><span class="o">=</span><span class="n">ListView</span><span class="o">.</span><span class="n">as_view</span><span class="p">(</span><span class="s2">&quot;user_list&quot;</span><span class="p">,</span> <span class="n">User</span><span class="p">,</span> <span class="s2">&quot;users.html&quot;</span><span class="p">),</span>
<span class="p">)</span>
<span class="n">app</span><span class="o">.</span><span class="n">add_url_rule</span><span class="p">(</span>
<span class="s2">&quot;/stories/&quot;</span><span class="p">,</span>
<span class="n">view_func</span><span class="o">=</span><span class="n">ListView</span><span class="o">.</span><span class="n">as_view</span><span class="p">(</span><span class="s2">&quot;story_list&quot;</span><span class="p">,</span> <span class="n">Story</span><span class="p">,</span> <span class="s2">&quot;stories.html&quot;</span><span class="p">),</span>
<span class="p">)</span>
</pre></div>
</div>
</section>
<section id="url-variables">
<h2>URL Variables<a class="headerlink" href="#url-variables" title="Link to this heading"></a></h2>
<p>Any variables captured by the URL are passed as keyword arguments to the
<code class="docutils literal notranslate"><span class="pre">dispatch_request</span></code> method, as they would be for a regular view
function.</p>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="k">class</span><span class="w"> </span><span class="nc">DetailView</span><span class="p">(</span><span class="n">View</span><span class="p">):</span>
<span class="k">def</span><span class="w"> </span><span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">model</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">model</span> <span class="o">=</span> <span class="n">model</span>
<span class="bp">self</span><span class="o">.</span><span class="n">template</span> <span class="o">=</span> <span class="sa">f</span><span class="s2">&quot;</span><span class="si">{</span><span class="n">model</span><span class="o">.</span><span class="vm">__name__</span><span class="o">.</span><span class="n">lower</span><span class="p">()</span><span class="si">}</span><span class="s2">/detail.html&quot;</span>
<span class="k">def</span><span class="w"> </span><span class="nf">dispatch_request</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="nb">id</span><span class="p">)</span>
<span class="n">item</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">model</span><span class="o">.</span><span class="n">query</span><span class="o">.</span><span class="n">get_or_404</span><span class="p">(</span><span class="nb">id</span><span class="p">)</span>
<span class="k">return</span> <span class="n">render_template</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">template</span><span class="p">,</span> <span class="n">item</span><span class="o">=</span><span class="n">item</span><span class="p">)</span>
<span class="n">app</span><span class="o">.</span><span class="n">add_url_rule</span><span class="p">(</span>
<span class="s2">&quot;/users/&lt;int:id&gt;&quot;</span><span class="p">,</span>
<span class="n">view_func</span><span class="o">=</span><span class="n">DetailView</span><span class="o">.</span><span class="n">as_view</span><span class="p">(</span><span class="s2">&quot;user_detail&quot;</span><span class="p">,</span> <span class="n">User</span><span class="p">)</span>
<span class="p">)</span>
</pre></div>
</div>
</section>
<section id="view-lifetime-and-self">
<h2>View Lifetime and <code class="docutils literal notranslate"><span class="pre">self</span></code><a class="headerlink" href="#view-lifetime-and-self" title="Link to this heading"></a></h2>
<p>By default, a new instance of the view class is created every time a
request is handled. This means that it is safe to write other data to
<code class="docutils literal notranslate"><span class="pre">self</span></code> during the request, since the next request will not see it,
unlike other forms of global state.</p>
<p>However, if your view class needs to do a lot of complex initialization,
doing it for every request is unnecessary and can be inefficient. To
avoid this, set <a class="reference internal" href="api.html#flask.views.View.init_every_request" title="flask.views.View.init_every_request"><code class="xref py py-attr docutils literal notranslate"><span class="pre">View.init_every_request</span></code></a> to <code class="docutils literal notranslate"><span class="pre">False</span></code>, which will
only create one instance of the class and use it for every request. In
this case, writing to <code class="docutils literal notranslate"><span class="pre">self</span></code> is not safe. If you need to store data
during the request, use <a class="reference internal" href="api.html#flask.g" title="flask.g"><code class="xref py py-data docutils literal notranslate"><span class="pre">g</span></code></a> instead.</p>
<p>In the <code class="docutils literal notranslate"><span class="pre">ListView</span></code> example, nothing writes to <code class="docutils literal notranslate"><span class="pre">self</span></code> during the
request, so it is more efficient to create a single instance.</p>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="k">class</span><span class="w"> </span><span class="nc">ListView</span><span class="p">(</span><span class="n">View</span><span class="p">):</span>
<span class="n">init_every_request</span> <span class="o">=</span> <span class="kc">False</span>
<span class="k">def</span><span class="w"> </span><span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">model</span><span class="p">,</span> <span class="n">template</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">model</span> <span class="o">=</span> <span class="n">model</span>
<span class="bp">self</span><span class="o">.</span><span class="n">template</span> <span class="o">=</span> <span class="n">template</span>
<span class="k">def</span><span class="w"> </span><span class="nf">dispatch_request</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">items</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">model</span><span class="o">.</span><span class="n">query</span><span class="o">.</span><span class="n">all</span><span class="p">()</span>
<span class="k">return</span> <span class="n">render_template</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">template</span><span class="p">,</span> <span class="n">items</span><span class="o">=</span><span class="n">items</span><span class="p">)</span>
</pre></div>
</div>
<p>Different instances will still be created each for each <code class="docutils literal notranslate"><span class="pre">as_view</span></code>
call, but not for each request to those views.</p>
</section>
<section id="view-decorators">
<h2>View Decorators<a class="headerlink" href="#view-decorators" title="Link to this heading"></a></h2>
<p>The view class itself is not the view function. View decorators need to
be applied to the view function returned by <code class="docutils literal notranslate"><span class="pre">as_view</span></code>, not the class
itself. Set <a class="reference internal" href="api.html#flask.views.View.decorators" title="flask.views.View.decorators"><code class="xref py py-attr docutils literal notranslate"><span class="pre">View.decorators</span></code></a> to a list of decorators to apply.</p>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="k">class</span><span class="w"> </span><span class="nc">UserList</span><span class="p">(</span><span class="n">View</span><span class="p">):</span>
<span class="n">decorators</span> <span class="o">=</span> <span class="p">[</span><span class="n">cache</span><span class="p">(</span><span class="n">minutes</span><span class="o">=</span><span class="mi">2</span><span class="p">),</span> <span class="n">login_required</span><span class="p">]</span>
<span class="n">app</span><span class="o">.</span><span class="n">add_url_rule</span><span class="p">(</span><span class="s1">&#39;/users/&#39;</span><span class="p">,</span> <span class="n">view_func</span><span class="o">=</span><span class="n">UserList</span><span class="o">.</span><span class="n">as_view</span><span class="p">())</span>
</pre></div>
</div>
<p>If you didn’t set <code class="docutils literal notranslate"><span class="pre">decorators</span></code>, you could apply them manually instead.
This is equivalent to:</p>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="n">view</span> <span class="o">=</span> <span class="n">UserList</span><span class="o">.</span><span class="n">as_view</span><span class="p">(</span><span class="s2">&quot;users_list&quot;</span><span class="p">)</span>
<span class="n">view</span> <span class="o">=</span> <span class="n">cache</span><span class="p">(</span><span class="n">minutes</span><span class="o">=</span><span class="mi">2</span><span class="p">)(</span><span class="n">view</span><span class="p">)</span>
<span class="n">view</span> <span class="o">=</span> <span class="n">login_required</span><span class="p">(</span><span class="n">view</span><span class="p">)</span>
<span class="n">app</span><span class="o">.</span><span class="n">add_url_rule</span><span class="p">(</span><span class="s1">&#39;/users/&#39;</span><span class="p">,</span> <span class="n">view_func</span><span class="o">=</span><span class="n">view</span><span class="p">)</span>
</pre></div>
</div>
<p>Keep in mind that order matters. If you’re used to <code class="docutils literal notranslate"><span class="pre">&#64;decorator</span></code> style,
this is equivalent to:</p>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="nd">@app</span><span class="o">.</span><span class="n">route</span><span class="p">(</span><span class="s2">&quot;/users/&quot;</span><span class="p">)</span>
<span class="nd">@login_required</span>
<span class="nd">@cache</span><span class="p">(</span><span class="n">minutes</span><span class="o">=</span><span class="mi">2</span><span class="p">)</span>
<span class="k">def</span><span class="w"> </span><span class="nf">user_list</span><span class="p">():</span>
<span class="o">...</span>
</pre></div>
</div>
</section>
<section id="method-hints">
<h2>Method Hints<a class="headerlink" href="#method-hints" title="Link to this heading"></a></h2>
<p>A common pattern is to register a view with <code class="docutils literal notranslate"><span class="pre">methods=[&quot;GET&quot;,</span> <span class="pre">&quot;POST&quot;]</span></code>,
then check <code class="docutils literal notranslate"><span class="pre">request.method</span> <span class="pre">==</span> <span class="pre">&quot;POST&quot;</span></code> to decide what to do. Setting
<a class="reference internal" href="api.html#flask.views.View.methods" title="flask.views.View.methods"><code class="xref py py-attr docutils literal notranslate"><span class="pre">View.methods</span></code></a> is equivalent to passing the list of methods to
<code class="docutils literal notranslate"><span class="pre">add_url_rule</span></code> or <code class="docutils literal notranslate"><span class="pre">route</span></code>.</p>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="k">class</span><span class="w"> </span><span class="nc">MyView</span><span class="p">(</span><span class="n">View</span><span class="p">):</span>
<span class="n">methods</span> <span class="o">=</span> <span class="p">[</span><span class="s2">&quot;GET&quot;</span><span class="p">,</span> <span class="s2">&quot;POST&quot;</span><span class="p">]</span>
<span class="k">def</span><span class="w"> </span><span class="nf">dispatch_request</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">if</span> <span class="n">request</span><span class="o">.</span><span class="n">method</span> <span class="o">==</span> <span class="s2">&quot;POST&quot;</span><span class="p">:</span>
<span class="o">...</span>
<span class="o">...</span>
<span class="n">app</span><span class="o">.</span><span class="n">add_url_rule</span><span class="p">(</span><span class="s1">&#39;/my-view&#39;</span><span class="p">,</span> <span class="n">view_func</span><span class="o">=</span><span class="n">MyView</span><span class="o">.</span><span class="n">as_view</span><span class="p">(</span><span class="s1">&#39;my-view&#39;</span><span class="p">))</span>
</pre></div>
</div>
<p>This is equivalent to the following, except further subclasses can
inherit or change the methods.</p>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="n">app</span><span class="o">.</span><span class="n">add_url_rule</span><span class="p">(</span>
<span class="s2">&quot;/my-view&quot;</span><span class="p">,</span>
<span class="n">view_func</span><span class="o">=</span><span class="n">MyView</span><span class="o">.</span><span class="n">as_view</span><span class="p">(</span><span class="s2">&quot;my-view&quot;</span><span class="p">),</span>
<span class="n">methods</span><span class="o">=</span><span class="p">[</span><span class="s2">&quot;GET&quot;</span><span class="p">,</span> <span class="s2">&quot;POST&quot;</span><span class="p">],</span>
<span class="p">)</span>
</pre></div>
</div>
</section>
<section id="method-dispatching-and-apis">
<h2>Method Dispatching and APIs<a class="headerlink" href="#method-dispatching-and-apis" title="Link to this heading"></a></h2>
<p>For APIs it can be helpful to use a different function for each HTTP
method. <a class="reference internal" href="api.html#flask.views.MethodView" title="flask.views.MethodView"><code class="xref py py-class docutils literal notranslate"><span class="pre">MethodView</span></code></a> extends the basic <a class="reference internal" href="api.html#flask.views.View" title="flask.views.View"><code class="xref py py-class docutils literal notranslate"><span class="pre">View</span></code></a> to dispatch
to different methods of the class based on the request method. Each HTTP
method maps to a method of the class with the same (lowercase) name.</p>
<p><a class="reference internal" href="api.html#flask.views.MethodView" title="flask.views.MethodView"><code class="xref py py-class docutils literal notranslate"><span class="pre">MethodView</span></code></a> automatically sets <a class="reference internal" href="api.html#flask.views.View.methods" title="flask.views.View.methods"><code class="xref py py-attr docutils literal notranslate"><span class="pre">View.methods</span></code></a> based on the
methods defined by the class. It even knows how to handle subclasses
that override or define other methods.</p>
<p>We can make a generic <code class="docutils literal notranslate"><span class="pre">ItemAPI</span></code> class that provides get (detail),
patch (edit), and delete methods for a given model. A <code class="docutils literal notranslate"><span class="pre">GroupAPI</span></code> can
provide get (list) and post (create) methods.</p>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="kn">from</span><span class="w"> </span><span class="nn">flask.views</span><span class="w"> </span><span class="kn">import</span> <span class="n">MethodView</span>
<span class="k">class</span><span class="w"> </span><span class="nc">ItemAPI</span><span class="p">(</span><span class="n">MethodView</span><span class="p">):</span>
<span class="n">init_every_request</span> <span class="o">=</span> <span class="kc">False</span>
<span class="k">def</span><span class="w"> </span><span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">model</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">model</span> <span class="o">=</span> <span class="n">model</span>
<span class="bp">self</span><span class="o">.</span><span class="n">validator</span> <span class="o">=</span> <span class="n">generate_validator</span><span class="p">(</span><span class="n">model</span><span class="p">)</span>
<span class="k">def</span><span class="w"> </span><span class="nf">_get_item</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="nb">id</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">model</span><span class="o">.</span><span class="n">query</span><span class="o">.</span><span class="n">get_or_404</span><span class="p">(</span><span class="nb">id</span><span class="p">)</span>
<span class="k">def</span><span class="w"> </span><span class="nf">get</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="nb">id</span><span class="p">):</span>
<span class="n">item</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">_get_item</span><span class="p">(</span><span class="nb">id</span><span class="p">)</span>
<span class="k">return</span> <span class="n">jsonify</span><span class="p">(</span><span class="n">item</span><span class="o">.</span><span class="n">to_json</span><span class="p">())</span>
<span class="k">def</span><span class="w"> </span><span class="nf">patch</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="nb">id</span><span class="p">):</span>
<span class="n">item</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">_get_item</span><span class="p">(</span><span class="nb">id</span><span class="p">)</span>
<span class="n">errors</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">validator</span><span class="o">.</span><span class="n">validate</span><span class="p">(</span><span class="n">item</span><span class="p">,</span> <span class="n">request</span><span class="o">.</span><span class="n">json</span><span class="p">)</span>
<span class="k">if</span> <span class="n">errors</span><span class="p">:</span>
<span class="k">return</span> <span class="n">jsonify</span><span class="p">(</span><span class="n">errors</span><span class="p">),</span> <span class="mi">400</span>
<span class="n">item</span><span class="o">.</span><span class="n">update_from_json</span><span class="p">(</span><span class="n">request</span><span class="o">.</span><span class="n">json</span><span class="p">)</span>
<span class="n">db</span><span class="o">.</span><span class="n">session</span><span class="o">.</span><span class="n">commit</span><span class="p">()</span>
<span class="k">return</span> <span class="n">jsonify</span><span class="p">(</span><span class="n">item</span><span class="o">.</span><span class="n">to_json</span><span class="p">())</span>
<span class="k">def</span><span class="w"> </span><span class="nf">delete</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="nb">id</span><span class="p">):</span>
<span class="n">item</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">_get_item</span><span class="p">(</span><span class="nb">id</span><span class="p">)</span>
<span class="n">db</span><span class="o">.</span><span class="n">session</span><span class="o">.</span><span class="n">delete</span><span class="p">(</span><span class="n">item</span><span class="p">)</span>
<span class="n">db</span><span class="o">.</span><span class="n">session</span><span class="o">.</span><span class="n">commit</span><span class="p">()</span>
<span class="k">return</span> <span class="s2">&quot;&quot;</span><span class="p">,</span> <span class="mi">204</span>
<span class="k">class</span><span class="w"> </span><span class="nc">GroupAPI</span><span class="p">(</span><span class="n">MethodView</span><span class="p">):</span>
<span class="n">init_every_request</span> <span class="o">=</span> <span class="kc">False</span>
<span class="k">def</span><span class="w"> </span><span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">model</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">model</span> <span class="o">=</span> <span class="n">model</span>
<span class="bp">self</span><span class="o">.</span><span class="n">validator</span> <span class="o">=</span> <span class="n">generate_validator</span><span class="p">(</span><span class="n">model</span><span class="p">,</span> <span class="n">create</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
<span class="k">def</span><span class="w"> </span><span class="nf">get</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">items</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">model</span><span class="o">.</span><span class="n">query</span><span class="o">.</span><span class="n">all</span><span class="p">()</span>
<span class="k">return</span> <span class="n">jsonify</span><span class="p">([</span><span class="n">item</span><span class="o">.</span><span class="n">to_json</span><span class="p">()</span> <span class="k">for</span> <span class="n">item</span> <span class="ow">in</span> <span class="n">items</span><span class="p">])</span>
<span class="k">def</span><span class="w"> </span><span class="nf">post</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">errors</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">validator</span><span class="o">.</span><span class="n">validate</span><span class="p">(</span><span class="n">request</span><span class="o">.</span><span class="n">json</span><span class="p">)</span>
<span class="k">if</span> <span class="n">errors</span><span class="p">:</span>
<span class="k">return</span> <span class="n">jsonify</span><span class="p">(</span><span class="n">errors</span><span class="p">),</span> <span class="mi">400</span>
<span class="n">db</span><span class="o">.</span><span class="n">session</span><span class="o">.</span><span class="n">add</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">model</span><span class="o">.</span><span class="n">from_json</span><span class="p">(</span><span class="n">request</span><span class="o">.</span><span class="n">json</span><span class="p">))</span>
<span class="n">db</span><span class="o">.</span><span class="n">session</span><span class="o">.</span><span class="n">commit</span><span class="p">()</span>
<span class="k">return</span> <span class="n">jsonify</span><span class="p">(</span><span class="n">item</span><span class="o">.</span><span class="n">to_json</span><span class="p">())</span>
<span class="k">def</span><span class="w"> </span><span class="nf">register_api</span><span class="p">(</span><span class="n">app</span><span class="p">,</span> <span class="n">model</span><span class="p">,</span> <span class="n">name</span><span class="p">):</span>
<span class="n">item</span> <span class="o">=</span> <span class="n">ItemAPI</span><span class="o">.</span><span class="n">as_view</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;</span><span class="si">{</span><span class="n">name</span><span class="si">}</span><span class="s2">-item&quot;</span><span class="p">,</span> <span class="n">model</span><span class="p">)</span>
<span class="n">group</span> <span class="o">=</span> <span class="n">GroupAPI</span><span class="o">.</span><span class="n">as_view</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;</span><span class="si">{</span><span class="n">name</span><span class="si">}</span><span class="s2">-group&quot;</span><span class="p">,</span> <span class="n">model</span><span class="p">)</span>
<span class="n">app</span><span class="o">.</span><span class="n">add_url_rule</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;/</span><span class="si">{</span><span class="n">name</span><span class="si">}</span><span class="s2">/&lt;int:id&gt;&quot;</span><span class="p">,</span> <span class="n">view_func</span><span class="o">=</span><span class="n">item</span><span class="p">)</span>
<span class="n">app</span><span class="o">.</span><span class="n">add_url_rule</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;/</span><span class="si">{</span><span class="n">name</span><span class="si">}</span><span class="s2">/&quot;</span><span class="p">,</span> <span class="n">view_func</span><span class="o">=</span><span class="n">group</span><span class="p">)</span>
<span class="n">register_api</span><span class="p">(</span><span class="n">app</span><span class="p">,</span> <span class="n">User</span><span class="p">,</span> <span class="s2">&quot;users&quot;</span><span class="p">)</span>
<span class="n">register_api</span><span class="p">(</span><span class="n">app</span><span class="p">,</span> <span class="n">Story</span><span class="p">,</span> <span class="s2">&quot;stories&quot;</span><span class="p">)</span>
</pre></div>
</div>
<p>This produces the following views, a standard REST API!</p>
<table class="docutils align-default">
<tbody>
<tr class="row-odd"><td><p>URL</p></td>
<td><p>Method</p></td>
<td><p>Description</p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">/users/</span></code></p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">GET</span></code></p></td>
<td><p>List all users</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">/users/</span></code></p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">POST</span></code></p></td>
<td><p>Create a new user</p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">/users/&lt;id&gt;</span></code></p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">GET</span></code></p></td>
<td><p>Show a single user</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">/users/&lt;id&gt;</span></code></p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">PATCH</span></code></p></td>
<td><p>Update a user</p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">/users/&lt;id&gt;</span></code></p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">DELETE</span></code></p></td>
<td><p>Delete a user</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">/stories/</span></code></p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">GET</span></code></p></td>
<td><p>List all stories</p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">/stories/</span></code></p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">POST</span></code></p></td>
<td><p>Create a new story</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">/stories/&lt;id&gt;</span></code></p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">GET</span></code></p></td>
<td><p>Show a single story</p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">/stories/&lt;id&gt;</span></code></p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">PATCH</span></code></p></td>
<td><p>Update a story</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">/stories/&lt;id&gt;</span></code></p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">DELETE</span></code></p></td>
<td><p>Delete a story</p></td>
</tr>
</tbody>
</table>
</section>
</section>
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<h3>Contents</h3>
<ul>
<li><a class="reference internal" href="#">Class-based Views</a><ul>
<li><a class="reference internal" href="#basic-reusable-view">Basic Reusable View</a></li>
<li><a class="reference internal" href="#url-variables">URL Variables</a></li>
<li><a class="reference internal" href="#view-lifetime-and-self">View Lifetime and <code class="docutils literal notranslate"><span class="pre">self</span></code></a></li>
<li><a class="reference internal" href="#view-decorators">View Decorators</a></li>
<li><a class="reference internal" href="#method-hints">Method Hints</a></li>
<li><a class="reference internal" href="#method-dispatching-and-apis">Method Dispatching and APIs</a></li>
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