title: customizing django admin ChangeForm template / adding custom content
body: <p>I'm able to insert (lame) static text onto the change form admin page, but I'd really like it to use the context of the current object being edited! </p>
  
  <p>For instance, I want to format on the MyObject change form a URL to include the ID from a ForeignKey connected object (<code>obj</code>) as a link.</p>
  
  <p>My admin objects:</p>
  
  <pre><code>class MyObjectChangeForm(forms.ModelForm):
      class Meta:
          model = MyObject
          fields = ('field1', 'obj',)
  
  class MyObjectAdmin(admin.ModelAdmin):
      form = MyObjectChangeForm
      list_display = ('field1', 'obj')
      def render_change_form(self, request, context, *args, **kwargs):
          self.change_form_template = 'admin/my_change_form.html'
          extra = {'lame_static_text': "something static",}
          context.update(extra)
          return super(MyObjectAdmin, self).render_change_form(request,
              context, *args, **kwargs)
  </code></pre>
  
  <p>My template <code>templates/admin/my_change_form.html</code>:</p>
  
  <pre><code>{% extends "admin/change_form.html" %}
  
  {% block form_top %}
      {{ lame_static_text }}
      &lt;a href="http://example.com/abc/{{ adminform.data.obj.id }}?"/&gt;View Website&lt;/a&gt;
  {% endblock %}
  </code></pre>
  
  <p>The <code>{{adminform.data.obj.id}}</code> call obviously doesn't work, but I'd like something along those lines. </p>
  
  <p>How do I insert dynamic context from the current object into the admin change form?</p>