[#2554] Refactor group_list to only query necessary fields

Refactor organization/group_list to only query the necessary fields by default
(id, name, title, package_count) depending on the required sort. This massively
speeds up the default query without all_fields. In part this is because then we
no longer need to get all fields in all groups on all cases to do the sorting.
There is a minor drawback in that then we can't take private datasets into
account when sorting by number of datasets. The actual number displayed will
take private datasets into account, as this comes from the dictization, but
there might be inconsistencies (note that the "order by datasets option" is
not offered by default on the UI)

ckan/logic/action/get.py

@@ -392,8 +392,21 @@ def _group_or_org_list(context, data_dict, is_org=False):
                                                'package_count', 'title'],
                                total=1)
 
-    query = model.Session.query(model.Group)
+    if sort_info and sort_info[0][0] == 'package_count':
+        query = model.Session.query(model.Group.id,
+                                    model.Group.name,
+                                    sqlalchemy.func.count(model.Group.id))
+
+        query = query.filter(model.Member.group_id == model.Group.id) \
+                     .filter(model.Member.table_id == model.Package.id) \
+                     .filter(model.Member.table_name == 'package') \
+                     .filter(model.Package.state == 'active')
+    else:
+        query = model.Session.query(model.Group.id,
+                                    model.Group.name)
+
     query = query.filter(model.Group.state == 'active')
+
     if groups:
         query = query.filter(model.Group.name.in_(groups))
     if q:
@@ -407,27 +420,37 @@ def _group_or_org_list(context, data_dict, is_org=False):
     query = query.filter(model.Group.is_organization == is_org)
     if not is_org:
         query = query.filter(model.Group.type == group_type)
+    if sort_info:
+        sort_field = sort_info[0][0]
+        sort_direction = sort_info[0][1]
+        if sort_field == 'package_count':
+            query = query.group_by(model.Group.id, model.Group.name)
+            sort_model_field = sqlalchemy.func.count(model.Group.id)
+        elif sort_field == 'name':
+            sort_model_field = model.Group.name
+        elif sort_field == 'title':
+            sort_model_field = model.Group.title
+
+        if sort_direction == 'asc':
+            query = query.order_by(sqlalchemy.asc(sort_model_field))
+        else:
+            query = query.order_by(sqlalchemy.desc(sort_model_field))
 
     groups = query.all()
 
-    action = 'organization_show' if is_org else 'group_show'
-
-    group_list = []
-    for group in groups:
-        data_dict['id'] = group.id
-
-        for key in ('include_extras', 'include_tags', 'include_users',
-                    'include_groups', 'include_followers'):
-            if key not in data_dict:
-                data_dict[key] = False
-
-        group_list.append(logic.get_action(action)(context, data_dict))
-
-    group_list = sorted(group_list, key=lambda x: x[sort_info[0][0]],
-        reverse=sort_info[0][1] == 'desc')
-
-    if not all_fields:
-        group_list = [group[ref_group_by] for group in group_list]
+    if all_fields:
+        action = 'organization_show' if is_org else 'group_show'
+        group_list = []
+        for group in groups:
+            data_dict['id'] = group.id
+            for key in ('include_extras', 'include_tags', 'include_users',
+                        'include_groups', 'include_followers'):
+                if key not in data_dict:
+                    data_dict[key] = False
+
+            group_list.append(logic.get_action(action)(context, data_dict))
+    else:
+        group_list = [getattr(group, ref_group_by) for group in groups]
 
     return group_list