Fixed #20836 -- Ensure that the ForeignKey's to_field attribute is properly considered by the admin's interface when creating related objects.

Many thanks to Collin Anderson for the report and patch and to Peter Sheats for the test.

7 files changed, 29 insertions, 10 deletions

diff --git a/django/contrib/admin/options.py b/django/contrib/admin/options.py
index 72c3635b52..f53d655bfc 100644
--- a/django/contrib/admin/options.py
+++ b/django/contrib/admin/options.py
@@ -44,6 +44,7 @@ from django.views.decorators.csrf import csrf_protect
 
 
 IS_POPUP_VAR = '_popup'
+TO_FIELD_VAR = '_to_field'
 
 HORIZONTAL, VERTICAL = 1, 2
 # returns the <ul> class for a given radio_admin field
@@ -932,6 +933,8 @@ class ModelAdmin(BaseModelAdmin):
             'content_type_id': ContentType.objects.get_for_model(self.model).id,
             'save_as': self.save_as,
             'save_on_top': self.save_on_top,
+            'to_field_var': TO_FIELD_VAR,
+            'is_popup_var': IS_POPUP_VAR
         })
         if add and self.add_form_template is not None:
             form_template = self.add_form_template
@@ -951,13 +954,20 @@ class ModelAdmin(BaseModelAdmin):
         opts = obj._meta
         pk_value = obj._get_pk_val()
         preserved_filters = self.get_preserved_filters(request)
-
         msg_dict = {'name': force_text(opts.verbose_name), 'obj': force_text(obj)}
         # Here, we distinguish between different save types by checking for
         # the presence of keys in request.POST.
+
         if IS_POPUP_VAR in request.POST:
+            to_field = request.POST.get(TO_FIELD_VAR)
+            if to_field:
+                attr = str(to_field)
+            else:
+                attr = obj._meta.pk.attname
+            value = obj.serializable_value(attr)
             return SimpleTemplateResponse('admin/popup_response.html', {
-                'pk_value': escape(pk_value),
+                'pk_value': escape(pk_value), # for possible backwards-compatibility
+                'value': escape(value),
                 'obj': escapejs(obj)
             })
 
@@ -988,6 +998,7 @@ class ModelAdmin(BaseModelAdmin):
         """
         Determines the HttpResponse for the change_view stage.
         """
+
         opts = self.model._meta
         pk_value = obj._get_pk_val()
         preserved_filters = self.get_preserved_filters(request)
@@ -1224,6 +1235,7 @@ class ModelAdmin(BaseModelAdmin):
             title=_('Add %s') % force_text(opts.verbose_name),
             adminform=adminForm,
             is_popup=IS_POPUP_VAR in request.REQUEST,
+            to_field=request.REQUEST.get(TO_FIELD_VAR),
             media=media,
             inline_admin_formsets=inline_admin_formsets,
             errors=helpers.AdminErrorList(form, formsets),
@@ -1297,6 +1309,7 @@ class ModelAdmin(BaseModelAdmin):
             object_id=object_id,
             original=obj,
             is_popup=IS_POPUP_VAR in request.REQUEST,
+            to_field=request.REQUEST.get(TO_FIELD_VAR),
             media=media,
             inline_admin_formsets=inline_admin_formsets,
             errors=helpers.AdminErrorList(form, formsets),
@@ -1443,6 +1456,7 @@ class ModelAdmin(BaseModelAdmin):
             selection_note_all=selection_note_all % {'total_count': cl.result_count},
             title=cl.title,
             is_popup=cl.is_popup,
+            to_field=cl.to_field,
             cl=cl,
             media=media,
             has_add_permission=self.has_add_permission(request),
diff --git a/django/contrib/admin/templates/admin/change_form.html b/django/contrib/admin/templates/admin/change_form.html
index c6969f6cc8..1acfcd37db 100644
--- a/django/contrib/admin/templates/admin/change_form.html
+++ b/django/contrib/admin/templates/admin/change_form.html
@@ -39,7 +39,8 @@
 {% endblock %}
 <form {% if has_file_field %}enctype="multipart/form-data" {% endif %}action="{{ form_url }}" method="post" id="{{ opts.model_name }}_form">{% csrf_token %}{% block form_top %}{% endblock %}
 <div>
-{% if is_popup %}<input type="hidden" name="_popup" value="1" />{% endif %}
+{% if is_popup %}<input type="hidden" name="{{ is_popup_var }}" value="1" />{% endif %}
+{% if to_field %}<input type="hidden" name="{{ to_field_var }}" value="{{ to_field }}" />{% endif %}
 {% if save_on_top %}{% block submit_buttons_top %}{% submit_row %}{% endblock %}{% endif %}
 {% if errors %}
     <p class="errornote">
diff --git a/django/contrib/admin/templates/admin/change_list.html b/django/contrib/admin/templates/admin/change_list.html
index ce5c5b37a4..a5a31f9c67 100644
--- a/django/contrib/admin/templates/admin/change_list.html
+++ b/django/contrib/admin/templates/admin/change_list.html
@@ -54,7 +54,7 @@
           {% block object-tools-items %}
             <li>
               {% url cl.opts|admin_urlname:'add' as add_url %}
-              <a href="{% add_preserved_filters add_url is_popup %}" class="addlink">
+              <a href="{% add_preserved_filters add_url is_popup to_field %}" class="addlink">
                 {% blocktrans with cl.opts.verbose_name as name %}Add {{ name }}{% endblocktrans %}
               </a>
             </li>
diff --git a/django/contrib/admin/templates/admin/popup_response.html b/django/contrib/admin/templates/admin/popup_response.html
index 44833b2f93..281f0354ee 100644
--- a/django/contrib/admin/templates/admin/popup_response.html
+++ b/django/contrib/admin/templates/admin/popup_response.html
@@ -3,7 +3,7 @@
   <head><title></title></head>
   <body>
     <script type="text/javascript">
-      opener.dismissAddAnotherPopup(window, "{{ pk_value }}", "{{ obj }}");
+      opener.dismissAddAnotherPopup(window, "{{ value }}", "{{ obj }}");
     </script>
   </body>
 </html>
diff --git a/django/contrib/admin/templatetags/admin_urls.py b/django/contrib/admin/templatetags/admin_urls.py
index 5d9c5b5427..fd45bf306a 100644
--- a/django/contrib/admin/templatetags/admin_urls.py
+++ b/django/contrib/admin/templatetags/admin_urls.py
@@ -22,7 +22,7 @@ def admin_urlquote(value):
 
 
 @register.simple_tag(takes_context=True)
-def add_preserved_filters(context, url, popup=False):
+def add_preserved_filters(context, url, popup=False, to_field=None):
     opts = context.get('opts')
     preserved_filters = context.get('preserved_filters')
 
@@ -48,6 +48,9 @@ def add_preserved_filters(context, url, popup=False):
     if popup:
         from django.contrib.admin.options import IS_POPUP_VAR
         merged_qs[IS_POPUP_VAR] = 1
+    if to_field:
+        from django.contrib.admin.options import TO_FIELD_VAR
+        merged_qs[TO_FIELD_VAR] = to_field
 
     merged_qs.update(parsed_qs)
 
diff --git a/django/contrib/admin/views/main.py b/django/contrib/admin/views/main.py
index 3325747a9f..14f7655251 100644
--- a/django/contrib/admin/views/main.py
+++ b/django/contrib/admin/views/main.py
@@ -15,7 +15,7 @@ from django.utils.http import urlencode
 
 from django.contrib.admin import FieldListFilter
 from django.contrib.admin.exceptions import DisallowedModelAdminLookup
-from django.contrib.admin.options import IncorrectLookupParameters, IS_POPUP_VAR
+from django.contrib.admin.options import IncorrectLookupParameters, IS_POPUP_VAR, TO_FIELD_VAR
 from django.contrib.admin.util import (quote, get_fields_from_path,
     lookup_needs_distinct, prepare_lookup_value)
 
@@ -25,7 +25,6 @@ ORDER_VAR = 'o'
 ORDER_TYPE_VAR = 'ot'
 PAGE_VAR = 'p'
 SEARCH_VAR = 'q'
-TO_FIELD_VAR = 't'
 ERROR_FLAG = 'e'
 
 IGNORED_PARAMS = (
diff --git a/django/contrib/admin/widgets.py b/django/contrib/admin/widgets.py
index e5b590e0d0..fe6c9e13a9 100644
--- a/django/contrib/admin/widgets.py
+++ b/django/contrib/admin/widgets.py
@@ -248,16 +248,18 @@ class RelatedFieldWidgetWrapper(forms.Widget):
         return self.widget.media
 
     def render(self, name, value, *args, **kwargs):
+        from django.contrib.admin.views.main import TO_FIELD_VAR
         rel_to = self.rel.to
         info = (rel_to._meta.app_label, rel_to._meta.model_name)
         self.widget.choices = self.choices
         output = [self.widget.render(name, value, *args, **kwargs)]
         if self.can_add_related:
             related_url = reverse('admin:%s_%s_add' % info, current_app=self.admin_site.name)
+            url_params = '?%s=%s' % (TO_FIELD_VAR, self.rel.get_related_field().name)
             # TODO: "add_id_" is hard-coded here. This should instead use the
             # correct API to determine the ID dynamically.
-            output.append('<a href="%s" class="add-another" id="add_id_%s" onclick="return showAddAnotherPopup(this);"> '
-                          % (related_url, name))
+            output.append('<a href="%s%s" class="add-another" id="add_id_%s" onclick="return showAddAnotherPopup(this);"> '
+                          % (related_url, url_params, name))
             output.append('<img src="%s" width="10" height="10" alt="%s"/></a>'
                           % (static('admin/img/icon_addlink.gif'), _('Add Another')))
         return mark_safe(''.join(output))