Fixed #24941 -- Added ModelAdmin.get_exclude().

Thanks Ola Sitarska for the initial patch.

django/contrib/admin/options.py

@@ -282,6 +282,12 @@ class BaseModelAdmin(six.with_metaclass(forms.MediaDefiningClass)):
         except AttributeError:
             return mark_safe(self.admin_site.empty_value_display)
 
+    def get_exclude(self, request, obj=None):
+        """
+        Hook for specifying exclude.
+        """
+        return self.exclude
+
     def get_fields(self, request, obj=None):
         """
         Hook for specifying fields.
@@ -605,13 +611,11 @@ class ModelAdmin(BaseModelAdmin):
             fields = kwargs.pop('fields')
         else:
             fields = flatten_fieldsets(self.get_fieldsets(request, obj))
-        if self.exclude is None:
+        excluded = self.get_exclude(request, obj)
-            exclude = []
+        exclude = [] if excluded is None else list(excluded)
-        else:
-            exclude = list(self.exclude)
         readonly_fields = self.get_readonly_fields(request, obj)
         exclude.extend(readonly_fields)
-        if self.exclude is None and hasattr(self.form, '_meta') and self.form._meta.exclude:
+        if excluded is None and hasattr(self.form, '_meta') and self.form._meta.exclude:
             # Take the custom ModelForm's Meta.exclude into account only if the
             # ModelAdmin doesn't define its own.
             exclude.extend(self.form._meta.exclude)
@@ -1851,12 +1855,10 @@ class InlineModelAdmin(BaseModelAdmin):
             fields = kwargs.pop('fields')
         else:
             fields = flatten_fieldsets(self.get_fieldsets(request, obj))
-        if self.exclude is None:
+        excluded = self.get_exclude(request, obj)
-            exclude = []
+        exclude = [] if excluded is None else list(excluded)
-        else:
-            exclude = list(self.exclude)
         exclude.extend(self.get_readonly_fields(request, obj))
-        if self.exclude is None and hasattr(self.form, '_meta') and self.form._meta.exclude:
+        if excluded is None and hasattr(self.form, '_meta') and self.form._meta.exclude:
             # Take the custom ModelForm's Meta.exclude into account only if the
             # InlineModelAdmin doesn't define its own.
             exclude.extend(self.form._meta.exclude)

docs/ref/contrib/admin/index.txt

@@ -1459,6 +1459,14 @@ templates used by the :class:`ModelAdmin` views:
     names on the changelist that will be linked to the change view, as described
     in the :attr:`ModelAdmin.list_display_links` section.
 
+.. method:: ModelAdmin.get_exclude(request, obj=None)
+
+    .. versionadded:: 1.11
+
+    The ``get_exclude`` method is given the ``HttpRequest`` and the ``obj``
+    being edited (or ``None`` on an add form) and is expected to return a list
+    of fields, as described in :attr:`ModelAdmin.exclude`.
+
 .. method:: ModelAdmin.get_fields(request, obj=None)
 
     The ``get_fields`` method is given the ``HttpRequest`` and the ``obj``

docs/releases/1.11.txt

@@ -68,6 +68,10 @@ Minor features
 
 * :attr:`.ModelAdmin.date_hierarchy` can now reference fields across relations.
 
+* The new :meth:`ModelAdmin.get_exclude()
+  <django.contrib.admin.ModelAdmin.get_exclude>` hook allows specifying the
+  exclude fields based on the request or model instance.
+
 :mod:`django.contrib.admindocs`
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

tests/modeladmin/tests.py

@@ -52,6 +52,7 @@ class ModelAdminTests(TestCase):
         self.assertEqual(list(ma.get_form(request).base_fields), ['name', 'bio', 'sign_date'])
         self.assertEqual(list(ma.get_fields(request)), ['name', 'bio', 'sign_date'])
         self.assertEqual(list(ma.get_fields(request, self.band)), ['name', 'bio', 'sign_date'])
+        self.assertIsNone(ma.get_exclude(request, self.band))
 
     def test_default_fieldsets(self):
         # fieldsets_add and fieldsets_change should return a special data structure that
@@ -279,6 +280,40 @@ class ModelAdminTests(TestCase):
             ['main_band', 'opening_band', 'day', 'id', 'DELETE']
         )
 
+    def test_overriding_get_exclude(self):
+        class BandAdmin(ModelAdmin):
+            def get_exclude(self, request, obj=None):
+                return ['name']
+
+        self.assertEqual(
+            list(BandAdmin(Band, self.site).get_form(request).base_fields),
+            ['bio', 'sign_date']
+        )
+
+    def test_get_exclude_overrides_exclude(self):
+        class BandAdmin(ModelAdmin):
+            exclude = ['bio']
+
+            def get_exclude(self, request, obj=None):
+                return ['name']
+
+        self.assertEqual(
+            list(BandAdmin(Band, self.site).get_form(request).base_fields),
+            ['bio', 'sign_date']
+        )
+
+    def test_get_exclude_takes_obj(self):
+        class BandAdmin(ModelAdmin):
+            def get_exclude(self, request, obj=None):
+                if obj:
+                    return ['sign_date']
+                return ['name']
+
+        self.assertEqual(
+            list(BandAdmin(Band, self.site).get_form(request, self.band).base_fields),
+            ['name', 'bio']
+        )
+
     def test_custom_form_validation(self):
         # If we specify a form, it should use it allowing custom validation to work
         # properly. This won't, however, break any of the admin widgets or media.
@@ -346,6 +381,52 @@ class ModelAdminTests(TestCase):
             list(list(ma.get_formsets_with_inlines(request))[0][0]().forms[0].fields),
             ['main_band', 'day', 'transport', 'id', 'DELETE'])
 
+    def test_formset_overriding_get_exclude_with_form_fields(self):
+        class AdminConcertForm(forms.ModelForm):
+            class Meta:
+                model = Concert
+                fields = ['main_band', 'opening_band', 'day', 'transport']
+
+        class ConcertInline(TabularInline):
+            form = AdminConcertForm
+            fk_name = 'main_band'
+            model = Concert
+
+            def get_exclude(self, request, obj=None):
+                return ['opening_band']
+
+        class BandAdmin(ModelAdmin):
+            inlines = [ConcertInline]
+
+        ma = BandAdmin(Band, self.site)
+        self.assertEqual(
+            list(list(ma.get_formsets_with_inlines(request))[0][0]().forms[0].fields),
+            ['main_band', 'day', 'transport', 'id', 'DELETE']
+        )
+
+    def test_formset_overriding_get_exclude_with_form_exclude(self):
+        class AdminConcertForm(forms.ModelForm):
+            class Meta:
+                model = Concert
+                exclude = ['day']
+
+        class ConcertInline(TabularInline):
+            form = AdminConcertForm
+            fk_name = 'main_band'
+            model = Concert
+
+            def get_exclude(self, request, obj=None):
+                return ['opening_band']
+
+        class BandAdmin(ModelAdmin):
+            inlines = [ConcertInline]
+
+        ma = BandAdmin(Band, self.site)
+        self.assertEqual(
+            list(list(ma.get_formsets_with_inlines(request))[0][0]().forms[0].fields),
+            ['main_band', 'day', 'transport', 'id', 'DELETE']
+        )
+
     def test_queryset_override(self):
         # If we need to override the queryset of a ModelChoiceField in our custom form
         # make sure that RelatedFieldWidgetWrapper doesn't mess that up.