ChangeForeignKeyAction.

shared/utils/admin_actions.py

@@ -124,3 +124,49 @@ class TargetActionBase(AdminActionBase):
                 'target': target_name,
                 'failure_count': failure_count}
 
+
+class ChangeForeignKeyAction(AdminActionBase):
+    # Subclass::
+    #   action_name = 'change_fieldname_action'
+    #   field_name_label = _("<field name>")
+    # title = _("Change <field name>")
+    # queryset_action_label = _("For the following items the <field name> will be changed:")
+    # action_button_label = _("Change <field name>")
+
+    def apply(self, queryset, form):
+        raise NotImplementedError("apply must be implemented by the subclass.")
+        # Subclass::
+        #   new_value = form.cleaned_data['new_value']
+        #   return change_fieldname_state(queryset, new_value)
+
+    def get_value_choices_queryset(self, modeladmin, request, queryset):
+        raise NotImplementedError("get_value_choices_queryset must be implemented by the subclass.")
+
+    def get_form_class(self, modeladmin, request, queryset):
+        class ChooseValueForm(AdminActionBase.BaseForm):
+            new_value = forms.ModelChoiceField(
+                label=_("Choose %(field_name)s" % {'field_name': self.field_name_label}),
+                queryset=self.get_value_choices_queryset(modeladmin, request, queryset),
+                required=True)
+        return ChooseValueForm
+
+    def get_message(self, form, count):
+        new_value = form.cleaned_data['new_value']
+        return ngettext(
+            'Successfully changed %(field_name)s of %(count)d item to %(new_value)s.',
+            'Successfully changed %(field_name)s of %(count)d items to %(new_value)s.',
+            count) % {
+                'field_name': self.field_name_label,
+                'count': count,
+                'new_value': new_value}
+
+    def get_failure_message(self, form, count, failure_count):
+        new_value = form.cleaned_data['new_value']
+        return ngettext(
+            'Successfully changed %(field_name)s of %(count)d item to %(new_value)s, %(failure_count)s failed or skipped.',
+            'Successfully changed %(field_name)s of %(count)d items to %(new_value)s, %(failure_count)s failed or skipped.',
+            count) % {
+                'field_name': self.field_name_label,
+                'count': count,
+                'new_value': new_value,
+                'failure_count': failure_count}