Backport common mixin and generics improvements

* Rename get_object_list to get_source_queryset.
* Add uniqueness validation to SingleObjectCreateView.
* Remove MultipleInstanceActionMixin.
* Backport MultipleObjectMixin improvements.
* Remove ObjectListPermissionFilterMixin.
* Add and improve tests.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/document_parsing/views.py

@@ -10,6 +10,7 @@ from mayan.apps.common.generics import (
     FormView, MultipleObjectConfirmActionView, SingleObjectDetailView,
     SingleObjectDownloadView, SingleObjectEditView, SingleObjectListView
 )
+from mayan.apps.common.mixins import ExternalObjectMixin
 from mayan.apps.documents.forms import DocumentTypeFilteredSelectForm
 from mayan.apps.documents.models import Document, DocumentPage, DocumentType
 
@@ -93,7 +94,7 @@ class DocumentParsingErrorsListView(SingleObjectListView):
             ) % self.get_document(),
         }
 
-    def get_object_list(self):
+    def get_source_queryset(self):
         return self.get_document().latest_version.parsing_errors.all()
 
 
@@ -136,19 +137,21 @@ class DocumentSubmitView(MultipleObjectConfirmActionView):
         instance.submit_for_parsing()
 
 
-class DocumentTypeSettingsEditView(SingleObjectEditView):
+class DocumentTypeSettingsEditView(ExternalObjectMixin, SingleObjectEditView):
+    external_object_class = DocumentType
+    external_object_permission = permission_document_type_parsing_setup
+    external_object_pk_url_kwarg = 'pk'
     fields = ('auto_parsing',)
-    object_permission = permission_document_type_parsing_setup
-    post_action_redirect = reverse_lazy('documents:document_type_list')
+    post_action_redirect = reverse_lazy(viewname='documents:document_type_list')
 
     def get_document_type(self):
-        return get_object_or_404(klass=DocumentType, pk=self.kwargs['pk'])
+        return self.external_object
 
     def get_extra_context(self):
         return {
             'object': self.get_document_type(),
             'title': _(
-                'Edit parsing settings for document type: %s'
+                'Edit parsing settings for document type: %s.'
             ) % self.get_document_type()
         }
 
@@ -195,5 +198,5 @@ class ParseErrorListView(SingleObjectListView):
     }
     view_permission = permission_document_type_parsing_setup
 
-    def get_object_list(self):
+    def get_source_queryset(self):
         return DocumentVersionParseError.objects.all()