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  <div class="section" id="s-module-django.dispatch">
<span id="s-signals"></span><span id="module-django.dispatch"></span><span id="signals"></span><h1>Signals<a class="headerlink" href="#module-django.dispatch" title="Permalink to this headline">¶</a></h1>
<p>Django includes a &#8220;signal dispatcher&#8221; which helps allow decoupled applications
get notified when actions occur elsewhere in the framework. In a nutshell,
signals allow certain <em>senders</em> to notify a set of <em>receivers</em> that some action
has taken place. They&#8217;re especially useful when many pieces of code may be
interested in the same events.</p>
<p>Django provides a <a class="reference internal" href="../ref/signals.html"><span class="doc">set of built-in signals</span></a> that let user
code get notified by Django itself of certain actions. These include some useful
notifications:</p>
<ul>
<li><p class="first"><a class="reference internal" href="../ref/signals.html#django.db.models.signals.pre_save" title="django.db.models.signals.pre_save"><code class="xref py py-data docutils literal"><span class="pre">django.db.models.signals.pre_save</span></code></a> &amp;
<a class="reference internal" href="../ref/signals.html#django.db.models.signals.post_save" title="django.db.models.signals.post_save"><code class="xref py py-data docutils literal"><span class="pre">django.db.models.signals.post_save</span></code></a></p>
<p>Sent before or after a model&#8217;s <a class="reference internal" href="../ref/models/instances.html#django.db.models.Model.save" title="django.db.models.Model.save"><code class="xref py py-meth docutils literal"><span class="pre">save()</span></code></a> method
is called.</p>
</li>
<li><p class="first"><a class="reference internal" href="../ref/signals.html#django.db.models.signals.pre_delete" title="django.db.models.signals.pre_delete"><code class="xref py py-data docutils literal"><span class="pre">django.db.models.signals.pre_delete</span></code></a> &amp;
<a class="reference internal" href="../ref/signals.html#django.db.models.signals.post_delete" title="django.db.models.signals.post_delete"><code class="xref py py-data docutils literal"><span class="pre">django.db.models.signals.post_delete</span></code></a></p>
<p>Sent before or after a model&#8217;s <a class="reference internal" href="../ref/models/instances.html#django.db.models.Model.delete" title="django.db.models.Model.delete"><code class="xref py py-meth docutils literal"><span class="pre">delete()</span></code></a>
method or queryset&#8217;s <a class="reference internal" href="../ref/models/querysets.html#django.db.models.query.QuerySet.delete" title="django.db.models.query.QuerySet.delete"><code class="xref py py-meth docutils literal"><span class="pre">delete()</span></code></a>
method is called.</p>
</li>
<li><p class="first"><a class="reference internal" href="../ref/signals.html#django.db.models.signals.m2m_changed" title="django.db.models.signals.m2m_changed"><code class="xref py py-data docutils literal"><span class="pre">django.db.models.signals.m2m_changed</span></code></a></p>
<p>Sent when a <a class="reference internal" href="../ref/models/fields.html#django.db.models.ManyToManyField" title="django.db.models.ManyToManyField"><code class="xref py py-class docutils literal"><span class="pre">ManyToManyField</span></code></a> on a model is changed.</p>
</li>
<li><p class="first"><a class="reference internal" href="../ref/signals.html#django.core.signals.request_started" title="django.core.signals.request_started"><code class="xref py py-data docutils literal"><span class="pre">django.core.signals.request_started</span></code></a> &amp;
<a class="reference internal" href="../ref/signals.html#django.core.signals.request_finished" title="django.core.signals.request_finished"><code class="xref py py-data docutils literal"><span class="pre">django.core.signals.request_finished</span></code></a></p>
<p>Sent when Django starts or finishes an HTTP request.</p>
</li>
</ul>
<p>See the <a class="reference internal" href="../ref/signals.html"><span class="doc">built-in signal documentation</span></a> for a complete list,
and a complete explanation of each signal.</p>
<p>You can also <a class="reference internal" href="#defining-and-sending-signals">define and send your own custom signals</a>; see below.</p>
<div class="section" id="s-listening-to-signals">
<span id="listening-to-signals"></span><h2>Listening to signals<a class="headerlink" href="#listening-to-signals" title="Permalink to this headline">¶</a></h2>
<p>To receive a signal, you need to register a <em>receiver</em> function that gets
called when the signal is sent by using the <a class="reference internal" href="#django.dispatch.Signal.connect" title="django.dispatch.Signal.connect"><code class="xref py py-meth docutils literal"><span class="pre">Signal.connect()</span></code></a> method:</p>
<dl class="method">
<dt id="django.dispatch.Signal.connect">
<code class="descclassname">Signal.</code><code class="descname">connect</code>(<em>receiver</em>, <em>sender=None</em>, <em>weak=True</em>, <em>dispatch_uid=None</em>)<a class="reference internal" href="../_modules/django/dispatch/dispatcher.html#Signal.connect"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.dispatch.Signal.connect" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>receiver</strong> &#8211; The callback function which will be connected to this
signal. See <a class="reference internal" href="#receiver-functions"><span class="std std-ref">Receiver functions</span></a> for more information.</li>
<li><strong>sender</strong> &#8211; Specifies a particular sender to receive signals from. See
<a class="reference internal" href="#connecting-to-specific-signals"><span class="std std-ref">Connecting to signals sent by specific senders</span></a> for more information.</li>
<li><strong>weak</strong> &#8211; Django stores signal handlers as weak references by
default. Thus, if your receiver is a local function, it may be
garbage collected. To prevent this, pass <code class="docutils literal"><span class="pre">weak=False</span></code> when you call
the signal&#8217;s <code class="docutils literal"><span class="pre">connect()</span></code> method.</li>
<li><strong>dispatch_uid</strong> &#8211; A unique identifier for a signal receiver in cases
where duplicate signals may be sent. See
<a class="reference internal" href="#preventing-duplicate-signals"><span class="std std-ref">Preventing duplicate signals</span></a> for more information.</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>

<p>Let&#8217;s see how this works by registering a signal that
gets called after each HTTP request is finished. We&#8217;ll be connecting to the
<a class="reference internal" href="../ref/signals.html#django.core.signals.request_finished" title="django.core.signals.request_finished"><code class="xref py py-data docutils literal"><span class="pre">request_finished</span></code></a> signal.</p>
<div class="section" id="s-receiver-functions">
<span id="s-id1"></span><span id="receiver-functions"></span><span id="id1"></span><h3>Receiver functions<a class="headerlink" href="#receiver-functions" title="Permalink to this headline">¶</a></h3>
<p>First, we need to define a receiver function. A receiver can be any Python
function or method:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="k">def</span> <span class="nf">my_callback</span><span class="p">(</span><span class="n">sender</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
    <span class="nb">print</span><span class="p">(</span><span class="s2">&quot;Request finished!&quot;</span><span class="p">)</span>
</pre></div>
</div>
<p>Notice that the function takes a <code class="docutils literal"><span class="pre">sender</span></code> argument, along with wildcard
keyword arguments (<code class="docutils literal"><span class="pre">**kwargs</span></code>); all signal handlers must take these arguments.</p>
<p>We&#8217;ll look at senders <a class="reference internal" href="#connecting-to-signals-sent-by-specific-senders">a bit later</a>, but right now look at the <code class="docutils literal"><span class="pre">**kwargs</span></code>
argument. All signals send keyword arguments, and may change those keyword
arguments at any time. In the case of
<a class="reference internal" href="../ref/signals.html#django.core.signals.request_finished" title="django.core.signals.request_finished"><code class="xref py py-data docutils literal"><span class="pre">request_finished</span></code></a>, it&#8217;s documented as sending no
arguments, which means we might be tempted to write our signal handling as
<code class="docutils literal"><span class="pre">my_callback(sender)</span></code>.</p>
<p>This would be wrong &#8211; in fact, Django will throw an error if you do so. That&#8217;s
because at any point arguments could get added to the signal and your receiver
must be able to handle those new arguments.</p>
</div>
<div class="section" id="s-connecting-receiver-functions">
<span id="s-id2"></span><span id="connecting-receiver-functions"></span><span id="id2"></span><h3>Connecting receiver functions<a class="headerlink" href="#connecting-receiver-functions" title="Permalink to this headline">¶</a></h3>
<p>There are two ways you can connect a receiver to a signal. You can take the
manual connect route:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">django.core.signals</span> <span class="k">import</span> <span class="n">request_finished</span>

<span class="n">request_finished</span><span class="o">.</span><span class="n">connect</span><span class="p">(</span><span class="n">my_callback</span><span class="p">)</span>
</pre></div>
</div>
<p>Alternatively, you can use a <a class="reference internal" href="#django.dispatch.receiver" title="django.dispatch.receiver"><code class="xref py py-func docutils literal"><span class="pre">receiver()</span></code></a> decorator:</p>
<dl class="function">
<dt id="django.dispatch.receiver">
<code class="descname">receiver</code>(<em>signal</em>)<a class="reference internal" href="../_modules/django/dispatch/dispatcher.html#receiver"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.dispatch.receiver" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>signal</strong> &#8211; A signal or a list of signals to connect a function to.</td>
</tr>
</tbody>
</table>
</dd></dl>

<p>Here&#8217;s how you connect with the decorator:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">django.core.signals</span> <span class="k">import</span> <span class="n">request_finished</span>
<span class="kn">from</span> <span class="nn">django.dispatch</span> <span class="k">import</span> <span class="n">receiver</span>

<span class="nd">@receiver</span><span class="p">(</span><span class="n">request_finished</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">my_callback</span><span class="p">(</span><span class="n">sender</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
    <span class="nb">print</span><span class="p">(</span><span class="s2">&quot;Request finished!&quot;</span><span class="p">)</span>
</pre></div>
</div>
<p>Now, our <code class="docutils literal"><span class="pre">my_callback</span></code> function will be called each time a request finishes.</p>
<div class="admonition-where-should-this-code-live admonition">
<p class="first admonition-title">Where should this code live?</p>
<p>Strictly speaking, signal handling and registration code can live anywhere
you like, although it&#8217;s recommended to avoid the application&#8217;s root module
and its <code class="docutils literal"><span class="pre">models</span></code> module to minimize side-effects of importing code.</p>
<p>In practice, signal handlers are usually defined in a <code class="docutils literal"><span class="pre">signals</span></code>
submodule of the application they relate to. Signal receivers are
connected in the <a class="reference internal" href="../ref/applications.html#django.apps.AppConfig.ready" title="django.apps.AppConfig.ready"><code class="xref py py-meth docutils literal"><span class="pre">ready()</span></code></a> method of your
application configuration class. If you&#8217;re using the <a class="reference internal" href="#django.dispatch.receiver" title="django.dispatch.receiver"><code class="xref py py-func docutils literal"><span class="pre">receiver()</span></code></a>
decorator, simply import the <code class="docutils literal"><span class="pre">signals</span></code> submodule inside
<a class="reference internal" href="../ref/applications.html#django.apps.AppConfig.ready" title="django.apps.AppConfig.ready"><code class="xref py py-meth docutils literal"><span class="pre">ready()</span></code></a>.</p>
<div class="last versionchanged">
<span class="title">Changed in Django 1.7:</span> <p>Since <a class="reference internal" href="../ref/applications.html#django.apps.AppConfig.ready" title="django.apps.AppConfig.ready"><code class="xref py py-meth docutils literal"><span class="pre">ready()</span></code></a> didn&#8217;t exist in previous
versions of Django, signal registration usually happened in the
<code class="docutils literal"><span class="pre">models</span></code> module.</p>
</div>
</div>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">The <a class="reference internal" href="../ref/applications.html#django.apps.AppConfig.ready" title="django.apps.AppConfig.ready"><code class="xref py py-meth docutils literal"><span class="pre">ready()</span></code></a> method may be executed more than
once during testing, so you may want to <a class="reference internal" href="#preventing-duplicate-signals"><span class="std std-ref">guard your signals from
duplication</span></a>, especially if you&#8217;re planning
to send them within tests.</p>
</div>
</div>
<div class="section" id="s-connecting-to-signals-sent-by-specific-senders">
<span id="s-connecting-to-specific-signals"></span><span id="connecting-to-signals-sent-by-specific-senders"></span><span id="connecting-to-specific-signals"></span><h3>Connecting to signals sent by specific senders<a class="headerlink" href="#connecting-to-signals-sent-by-specific-senders" title="Permalink to this headline">¶</a></h3>
<p>Some signals get sent many times, but you&#8217;ll only be interested in receiving a
certain subset of those signals. For example, consider the
<a class="reference internal" href="../ref/signals.html#django.db.models.signals.pre_save" title="django.db.models.signals.pre_save"><code class="xref py py-data docutils literal"><span class="pre">django.db.models.signals.pre_save</span></code></a> signal sent before a model gets saved.
Most of the time, you don&#8217;t need to know when <em>any</em> model gets saved &#8211; just
when one <em>specific</em> model is saved.</p>
<p>In these cases, you can register to receive signals sent only by particular
senders. In the case of <a class="reference internal" href="../ref/signals.html#django.db.models.signals.pre_save" title="django.db.models.signals.pre_save"><code class="xref py py-data docutils literal"><span class="pre">django.db.models.signals.pre_save</span></code></a>, the sender
will be the model class being saved, so you can indicate that you only want
signals sent by some model:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">django.db.models.signals</span> <span class="k">import</span> <span class="n">pre_save</span>
<span class="kn">from</span> <span class="nn">django.dispatch</span> <span class="k">import</span> <span class="n">receiver</span>
<span class="kn">from</span> <span class="nn">myapp.models</span> <span class="k">import</span> <span class="n">MyModel</span>


<span class="nd">@receiver</span><span class="p">(</span><span class="n">pre_save</span><span class="p">,</span> <span class="n">sender</span><span class="o">=</span><span class="n">MyModel</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">my_handler</span><span class="p">(</span><span class="n">sender</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
    <span class="o">...</span>
</pre></div>
</div>
<p>The <code class="docutils literal"><span class="pre">my_handler</span></code> function will only be called when an instance of <code class="docutils literal"><span class="pre">MyModel</span></code>
is saved.</p>
<p>Different signals use different objects as their senders; you&#8217;ll need to consult
the <a class="reference internal" href="../ref/signals.html"><span class="doc">built-in signal documentation</span></a> for details of each
particular signal.</p>
</div>
<div class="section" id="s-preventing-duplicate-signals">
<span id="s-id3"></span><span id="preventing-duplicate-signals"></span><span id="id3"></span><h3>Preventing duplicate signals<a class="headerlink" href="#preventing-duplicate-signals" title="Permalink to this headline">¶</a></h3>
<p>In some circumstances, the code connecting receivers to signals may run
multiple times. This can cause your receiver function to be registered more
than once, and thus called multiples times for a single signal event.</p>
<p>If this behavior is problematic (such as when using signals to
send an email whenever a model is saved), pass a unique identifier as
the <code class="docutils literal"><span class="pre">dispatch_uid</span></code> argument to identify your receiver function. This
identifier will usually be a string, although any hashable object will
suffice. The end result is that your receiver function will only be
bound to the signal once for each unique <code class="docutils literal"><span class="pre">dispatch_uid</span></code> value:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">django.core.signals</span> <span class="k">import</span> <span class="n">request_finished</span>

<span class="n">request_finished</span><span class="o">.</span><span class="n">connect</span><span class="p">(</span><span class="n">my_callback</span><span class="p">,</span> <span class="n">dispatch_uid</span><span class="o">=</span><span class="s2">&quot;my_unique_identifier&quot;</span><span class="p">)</span>
</pre></div>
</div>
</div>
</div>
<div class="section" id="s-defining-and-sending-signals">
<span id="defining-and-sending-signals"></span><h2>Defining and sending signals<a class="headerlink" href="#defining-and-sending-signals" title="Permalink to this headline">¶</a></h2>
<p>Your applications can take advantage of the signal infrastructure and provide
its own signals.</p>
<div class="section" id="s-defining-signals">
<span id="defining-signals"></span><h3>Defining signals<a class="headerlink" href="#defining-signals" title="Permalink to this headline">¶</a></h3>
<dl class="class">
<dt id="django.dispatch.Signal">
<em class="property">class </em><code class="descname">Signal</code>(<em>providing_args=list</em>)<a class="reference internal" href="../_modules/django/dispatch/dispatcher.html#Signal"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.dispatch.Signal" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>

<p>All signals are <a class="reference internal" href="#django.dispatch.Signal" title="django.dispatch.Signal"><code class="xref py py-class docutils literal"><span class="pre">django.dispatch.Signal</span></code></a> instances. The
<code class="docutils literal"><span class="pre">providing_args</span></code> is a list of the names of arguments the signal will provide
to listeners. This is purely documentational, however, as there is nothing that
checks that the signal actually provides these arguments to its listeners.</p>
<p>For example:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">django.dispatch</span>

<span class="n">pizza_done</span> <span class="o">=</span> <span class="n">django</span><span class="o">.</span><span class="n">dispatch</span><span class="o">.</span><span class="n">Signal</span><span class="p">(</span><span class="n">providing_args</span><span class="o">=</span><span class="p">[</span><span class="s2">&quot;toppings&quot;</span><span class="p">,</span> <span class="s2">&quot;size&quot;</span><span class="p">])</span>
</pre></div>
</div>
<p>This declares a <code class="docutils literal"><span class="pre">pizza_done</span></code> signal that will provide receivers with
<code class="docutils literal"><span class="pre">toppings</span></code> and <code class="docutils literal"><span class="pre">size</span></code> arguments.</p>
<p>Remember that you&#8217;re allowed to change this list of arguments at any time, so
getting the API right on the first try isn&#8217;t necessary.</p>
</div>
<div class="section" id="s-sending-signals">
<span id="sending-signals"></span><h3>Sending signals<a class="headerlink" href="#sending-signals" title="Permalink to this headline">¶</a></h3>
<p>There are two ways to send signals in Django.</p>
<dl class="method">
<dt id="django.dispatch.Signal.send">
<code class="descclassname">Signal.</code><code class="descname">send</code>(<em>sender</em>, <em>**kwargs</em>)<a class="reference internal" href="../_modules/django/dispatch/dispatcher.html#Signal.send"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.dispatch.Signal.send" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>

<dl class="method">
<dt id="django.dispatch.Signal.send_robust">
<code class="descclassname">Signal.</code><code class="descname">send_robust</code>(<em>sender</em>, <em>**kwargs</em>)<a class="reference internal" href="../_modules/django/dispatch/dispatcher.html#Signal.send_robust"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.dispatch.Signal.send_robust" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>

<p>To send a signal, call either <a class="reference internal" href="#django.dispatch.Signal.send" title="django.dispatch.Signal.send"><code class="xref py py-meth docutils literal"><span class="pre">Signal.send()</span></code></a> or <a class="reference internal" href="#django.dispatch.Signal.send_robust" title="django.dispatch.Signal.send_robust"><code class="xref py py-meth docutils literal"><span class="pre">Signal.send_robust()</span></code></a>.
You must provide the <code class="docutils literal"><span class="pre">sender</span></code> argument (which is a class most of the time),
and may provide as many other keyword arguments as you like.</p>
<p>For example, here&#8217;s how sending our <code class="docutils literal"><span class="pre">pizza_done</span></code> signal might look:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">PizzaStore</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
    <span class="o">...</span>

    <span class="k">def</span> <span class="nf">send_pizza</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">toppings</span><span class="p">,</span> <span class="n">size</span><span class="p">):</span>
        <span class="n">pizza_done</span><span class="o">.</span><span class="n">send</span><span class="p">(</span><span class="n">sender</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">__class__</span><span class="p">,</span> <span class="n">toppings</span><span class="o">=</span><span class="n">toppings</span><span class="p">,</span> <span class="n">size</span><span class="o">=</span><span class="n">size</span><span class="p">)</span>
        <span class="o">...</span>
</pre></div>
</div>
<p>Both <code class="docutils literal"><span class="pre">send()</span></code> and <code class="docutils literal"><span class="pre">send_robust()</span></code> return a list of tuple pairs
<code class="docutils literal"><span class="pre">[(receiver,</span> <span class="pre">response),</span> <span class="pre">...</span> <span class="pre">]</span></code>, representing the list of called receiver
functions and their response values.</p>
<p><code class="docutils literal"><span class="pre">send()</span></code> differs from <code class="docutils literal"><span class="pre">send_robust()</span></code> in how exceptions raised by receiver
functions are handled. <code class="docutils literal"><span class="pre">send()</span></code> does <em>not</em> catch any exceptions raised by
receivers; it simply allows errors to propagate. Thus not all receivers may
be notified of a signal in the face of an error.</p>
<p><code class="docutils literal"><span class="pre">send_robust()</span></code> catches all errors derived from Python&#8217;s <code class="docutils literal"><span class="pre">Exception</span></code> class,
and ensures all receivers are notified of the signal. If an error occurs, the
error instance is returned in the tuple pair for the receiver that raised the error.</p>
<div class="versionadded">
<span class="title">New in Django 1.8:</span> <p>The tracebacks are present on the <code class="docutils literal"><span class="pre">__traceback__</span></code> attribute
of the errors returned when calling <code class="docutils literal"><span class="pre">send_robust()</span></code>.</p>
</div>
</div>
</div>
<div class="section" id="s-disconnecting-signals">
<span id="disconnecting-signals"></span><h2>Disconnecting signals<a class="headerlink" href="#disconnecting-signals" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="django.dispatch.Signal.disconnect">
<code class="descclassname">Signal.</code><code class="descname">disconnect</code>(<em>receiver=None</em>, <em>sender=None</em>, <em>weak=True</em>, <em>dispatch_uid=None</em>)<a class="reference internal" href="../_modules/django/dispatch/dispatcher.html#Signal.disconnect"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#django.dispatch.Signal.disconnect" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>

<p>To disconnect a receiver from a signal, call <a class="reference internal" href="#django.dispatch.Signal.disconnect" title="django.dispatch.Signal.disconnect"><code class="xref py py-meth docutils literal"><span class="pre">Signal.disconnect()</span></code></a>. The
arguments are as described in <a class="reference internal" href="#django.dispatch.Signal.connect" title="django.dispatch.Signal.connect"><code class="xref py py-meth docutils literal"><span class="pre">Signal.connect()</span></code></a>. The method returns
<code class="docutils literal"><span class="pre">True</span></code> if a receiver was disconnected and <code class="docutils literal"><span class="pre">False</span></code> if not.</p>
<p>The <code class="docutils literal"><span class="pre">receiver</span></code> argument indicates the registered receiver to disconnect. It
may be <code class="docutils literal"><span class="pre">None</span></code> if <code class="docutils literal"><span class="pre">dispatch_uid</span></code> is used to identify the receiver.</p>
<div class="versionchanged">
<span class="title">Changed in Django 1.8:</span> <p>The boolean return value was added.</p>
</div>
</div>
</div>


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<li><a class="reference internal" href="#">Signals</a><ul>
<li><a class="reference internal" href="#listening-to-signals">Listening to signals</a><ul>
<li><a class="reference internal" href="#receiver-functions">Receiver functions</a></li>
<li><a class="reference internal" href="#connecting-receiver-functions">Connecting receiver functions</a></li>
<li><a class="reference internal" href="#connecting-to-signals-sent-by-specific-senders">Connecting to signals sent by specific senders</a></li>
<li><a class="reference internal" href="#preventing-duplicate-signals">Preventing duplicate signals</a></li>
</ul>
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<li><a class="reference internal" href="#defining-and-sending-signals">Defining and sending signals</a><ul>
<li><a class="reference internal" href="#defining-signals">Defining signals</a></li>
<li><a class="reference internal" href="#sending-signals">Sending signals</a></li>
</ul>
</li>
<li><a class="reference internal" href="#disconnecting-signals">Disconnecting signals</a></li>
</ul>
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