Fixed #17074 -- Improved first field detection in admin add form

Thanks Kidwind for the report and Julien Phalip for the initial
patch.

django/contrib/admin/helpers.py

@@ -46,20 +46,6 @@ class AdminForm(object):
                 **options
             )
 
-    def first_field(self):
-        try:
-            fieldset_name, fieldset_options = self.fieldsets[0]
-            field_name = fieldset_options['fields'][0]
-            if not isinstance(field_name, six.string_types):
-                field_name = field_name[0]
-            return self.form[field_name]
-        except (KeyError, IndexError):
-            pass
-        try:
-            return next(iter(self.form))
-        except StopIteration:
-            return None
-
     def _media(self):
         media = self.form.media
         for fs in self:

django/contrib/admin/templates/admin/change_form.html

@@ -66,8 +66,14 @@
 
 {% block submit_buttons_bottom %}{% submit_row %}{% endblock %}
 
-{% if adminform.first_field and add %}
-   <script type="text/javascript">document.getElementById("{{ adminform.first_field.id_for_label }}").focus();</script>
+{% if adminform and add %}
+    <script type="text/javascript">
+        (function($) {
+            $(document).ready(function() {
+                $('form#{{ opts.module_name }}_form :input:visible:enabled:first').focus()
+            });
+        })(django.jQuery);
+    </script>
 {% endif %}
 
 {# JavaScript for prepopulated fields #}