Navigation: Related field support to SourceColumn

Add support to the SourceColumn class to resolve related fields
using the double underscore as separator. Columns that use related
no longer have to use throw away lambdas.

Signed-off-by: Roberto Rosario <Roberto.Rosario@mayan-edms.com>

HISTORY.rst

@@ -175,6 +175,8 @@
 - Upgraded from Celery 3.1.26 to 4.1.1. The following settings have been 
   renamed: CELERY_ALWAYS_EAGER to CELERY_TASK_ALWAYS_EAGER, 
   BROKER_URL to CELERY_BROKER_URL.
+- Internal change. Add support to the SourceColumn class to resolve
+  related fields using the double underscore as separator.
 
 3.1.9 (2018-11-01)
 ==================

mayan/apps/acls/managers.py

@@ -9,7 +9,7 @@ from django.db.models import Q
 from django.utils.translation import ugettext
 from django.utils.translation import ugettext_lazy as _
 
-from mayan.apps.common.utils import return_attrib, return_related
+from mayan.apps.common.utils import resolve_attribute, return_related
 from mayan.apps.permissions import Permission
 from mayan.apps.permissions.models import StoredPermission
 
@@ -46,7 +46,7 @@ class AccessControlListManager(models.Manager):
                 stored_permissions = (permissions.stored_permission,)
 
             if related:
-                obj = return_attrib(obj, related)
+                obj = resolve_attribute(obj, related)
 
             try:
                 parent_accessor = ModelPermission.get_inheritance(
@@ -199,7 +199,7 @@ class AccessControlListManager(models.Manager):
             return StoredPermission.objects.none()
         else:
             try:
-                parent_object = return_attrib(
+                parent_object = resolve_attribute(
                     obj=instance, attrib=parent_accessor
                 )
             except AttributeError:

mayan/apps/common/forms.py

@@ -11,7 +11,7 @@ from django.utils.translation import ugettext_lazy as _
 
 from .classes import Package
 from .models import UserLocaleProfile
-from .utils import return_attrib
+from .utils import resolve_attribute
 from .widgets import DisableableSelectWidget, PlainWidget, TextAreaDiv
 
 
@@ -43,7 +43,7 @@ class DetailForm(forms.ModelForm):
         super(DetailForm, self).__init__(*args, **kwargs)
 
         for extra_field in self.extra_fields:
-            result = return_attrib(self.instance, extra_field['field'])
+            result = resolve_attribute(self.instance, extra_field['field'])
             label = 'label' in extra_field and extra_field['label'] or None
             # TODO: Add others result types <=> Field types
             if isinstance(result, models.query.QuerySet):
@@ -53,7 +53,7 @@ class DetailForm(forms.ModelForm):
             else:
                 self.fields[extra_field['field']] = forms.CharField(
                     label=extra_field['label'],
-                    initial=return_attrib(
+                    initial=resolve_attribute(
                         self.instance,
                         extra_field['field'], None
                     ),

mayan/apps/common/templatetags/common_tags.py

@@ -10,7 +10,7 @@ import mayan
 
 from ..classes import Collection, Dashboard
 from ..literals import MESSAGE_SQLITE_WARNING
-from ..utils import check_for_sqlite, return_attrib
+from ..utils import check_for_sqlite, resolve_attribute
 
 register = Library()
 
@@ -30,7 +30,7 @@ def get_collections():
 def get_encoded_parameter(item, parameters_dict):
     result = {}
     for attrib_name, attrib in parameters_dict.items():
-        result[attrib_name] = return_attrib(item, attrib)
+        result[attrib_name] = resolve_attribute(item, attrib)
     return dumps(result)
 
 
@@ -41,7 +41,7 @@ def get_type(value):
 
 @register.filter
 def object_property(value, arg):
-    return return_attrib(value, arg)
+    return resolve_attribute(value, arg)
 
 
 @register.simple_tag

mayan/apps/common/utils.py

@@ -7,6 +7,7 @@ import tempfile
 import types
 
 from django.conf import settings
+from django.db.models.constants import LOOKUP_SEP
 from django.urls import resolve as django_resolve
 from django.urls.base import get_script_prefix
 from django.utils.datastructures import MultiValueDict
@@ -129,27 +130,34 @@ def resolve(path, urlconf=None):
     return django_resolve(path=path, urlconf=urlconf)
 
 
-def return_attrib(obj, attrib, arguments=None):
+def resolve_attribute(obj, attrib, arguments=None):
     if isinstance(attrib, types.FunctionType):
         return attrib(obj)
-    elif isinstance(
-        obj, dict_type
-    ) or isinstance(obj, dictionary_type):
+    elif isinstance(obj, dict_type) or isinstance(obj, dictionary_type):
         return obj[attrib]
     else:
-        result = reduce_function(getattr, attrib.split('.'), obj)
-        if isinstance(result, types.MethodType):
-            if arguments:
-                return result(**arguments)
+        try:
+            result = reduce_function(getattr, attrib.split('.'), obj)
+            if isinstance(result, types.MethodType):
+                if arguments:
+                    return result(**arguments)
+                else:
+                    return result()
             else:
-                return result()
-        else:
-            return result
+                return result
+        except AttributeError:
+            if LOOKUP_SEP in attrib:
+                attrib = attrib.replace(LOOKUP_SEP, '.')
+                return resolve_attribute(
+                    obj=obj, attrib=attrib, arguments=arguments
+                )
+            else:
+                raise
 
 
 def return_related(instance, related_field):
     """
-    This functions works in a similar method to return_attrib but is
+    This functions works in a similar method to resolve_attribute but is
     meant for related models. Support multiple levels of relationship
     using double underscore.
     """

mayan/apps/navigation/classes.py

@@ -8,14 +8,15 @@ from furl import furl
 from django.apps import apps
 from django.conf import settings
 from django.contrib.admin.utils import label_for_field
-from django.core.exceptions import PermissionDenied
+from django.core.exceptions import FieldDoesNotExist, PermissionDenied
+from django.db.models.constants import LOOKUP_SEP
 from django.shortcuts import resolve_url
 from django.template import VariableDoesNotExist, Variable
 from django.template.defaulttags import URLNode
 from django.urls import Resolver404, resolve
 from django.utils.encoding import force_str, force_text
 
-from mayan.apps.common.utils import return_attrib
+from mayan.apps.common.utils import resolve_attribute
 from mayan.apps.permissions import Permission
 
 logger = logging.getLogger(__name__)
@@ -469,6 +470,26 @@ class Separator(Link):
 class SourceColumn(object):
     _registry = {}
 
+    @staticmethod
+    def get_attribute_recursive(attribute, model):
+        """
+        Walk over the double underscore (__) separated path to the last
+        field. Returns the field name and the corresponding model class.
+        Used to introspect the label or short_description of a model's
+        attribute.
+        """
+        last_model = model
+        for part in attribute.split(LOOKUP_SEP):
+            last_model = model
+            try:
+                field = model._meta.get_field(part)
+            except FieldDoesNotExist:
+                break;
+            else:
+                model = field.related_model or field.model
+
+        return part, last_model
+
     @staticmethod
     def sort(columns):
         return sorted(columns, key=lambda x: x.order)
@@ -507,11 +528,13 @@ class SourceColumn(object):
 
     @property
     def label(self):
-        # TODO: Add support for related fields (dotted or double underscore attributes)
         if not self._label:
             if self.attribute:
+                name, model = SourceColumn.get_attribute_recursive(
+                    attribute=self.attribute, model=self.source._meta.model
+                )
                 self._label = label_for_field(
-                    name=self.attribute, model=self.source._meta.model
+                    name=name, model=model
                 )
             else:
                 self._label = 'Function'
@@ -520,7 +543,7 @@ class SourceColumn(object):
 
     def resolve(self, context):
         if self.attribute:
-            result = return_attrib(context['object'], self.attribute)
+            result = resolve_attribute(context['object'], self.attribute)
         elif self.func:
             result = self.func(context=context)