title: How can I get custom form field value from within Django Admin's response_change?
body: <p>I've added a custom functionality to a model by overriding <code>change_form.html</code>. Basically, I'm letting users change the objects of a model if these changes were approved by the admin. I added two buttons, named <code>accept-suggestion</code> and <code>decline-suggestion</code> and I intend to handle the custom functionality through <code>response_change</code> method:</p>
  <pre><code>def response_change(self, request, obj):
      if &quot;decline-suggestion&quot; in request.POST:
          # do stuff...
  
      if &quot;accept-suggestion&quot; in request.POST:
          # do stuff...
  </code></pre>
  <p>Both buttons will send an e-mail to the user saying if the suggestion was declined or approaved. So far so good. The problem is that I want to add the possibility to the admin write a brief justification explaining why the suggestion was declined. So I changed <code>change_form.html</code> again.</p>
  <pre class="lang-html prettyprint-override"><code>&lt;div class=&quot;submit-row&quot;&gt;
      &lt;div class=&quot;float-left&quot;&gt;
          &lt;a class=&quot;decline-button-outlined accordion&quot; type=&quot;button&quot; href=&quot;#&quot;&gt;DECLINE SUGGESTION&lt;/a&gt;
      &lt;/div&gt;
      &lt;div class=&quot;float-right&quot;&gt;
          &lt;input class=&quot;accept-button&quot; type=&quot;submit&quot; name=&quot;accept-suggestion&quot; value=&quot;ACEITAR SUGESTÃO&quot;&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  
  &lt;div class=&quot;additional-infos&quot;&gt;
      &lt;fieldset class=&quot;module aligned&quot;&gt;
          &lt;div class=&quot;form-row&quot;&gt;
              &lt;label for=&quot;decline-reasons&quot;&gt;Reasons for rejection:&lt;/label&gt;
              &lt;textarea
                  placeholder=&quot;If you find necessary, provide information on the reasons that led to the rejection of the suggestion&quot;
                  id=&quot;decline-reasons&quot; class=&quot;vLargeTextField&quot; rows=&quot;5&quot;&gt;&lt;/textarea&gt;
          &lt;/div&gt;
          &lt;div class=&quot;submit-row&quot;&gt;
              &lt;div class=&quot;float-right&quot;&gt;
                  &lt;input class=&quot;decline-button&quot; type=&quot;submit&quot; name=&quot;decline-suggestion&quot; value=&quot;DECLINE&quot;&gt;
              &lt;/div&gt;
          &lt;/div&gt;
      &lt;/fieldset&gt;
  &lt;/div&gt;
  </code></pre>
  <p>Is this the best approach? If so, how can I get the value of the <code>&lt;textarea&gt;</code> above from within <code>response_change</code>? If not, what would you suggest?</p>
  <p>Thank you very much!</p>