Revamp user_capabilities with new copy fields

Add copy fields corresponding to new server-side copying

Refactor the way user_capabilities are delivered
 - move the prefetch definition from views to serializer
 - store temporary mapping in serializer context
 - use serializer backlinks to denote polymorphic prefetch model exclusions

awx/main/utils/common.py

@@ -32,6 +32,7 @@ from django.db import DatabaseError
 from django.utils.translation import ugettext_lazy as _
 from django.db.models.fields.related import ForeignObjectRel, ManyToManyField
 from django.db.models.query import QuerySet
+from django.db.models import Q
 
 # Django REST Framework
 from rest_framework.exceptions import ParseError, PermissionDenied
@@ -44,7 +45,7 @@ logger = logging.getLogger('awx.main.utils')
 __all__ = ['get_object_or_400', 'get_object_or_403', 'camelcase_to_underscore', 'memoize', 'memoize_delete',
            'get_ansible_version', 'get_ssh_version', 'get_licenser', 'get_awx_version', 'update_scm_url',
            'get_type_for_model', 'get_model_for_type', 'copy_model_by_class',
-           'copy_m2m_relationships', 'cache_list_capabilities', 'to_python_boolean',
+           'copy_m2m_relationships', 'prefetch_page_capabilities', 'to_python_boolean',
            'ignore_inventory_computed_fields', 'ignore_inventory_group_removal',
            '_inventory_updates', 'get_pk_from_dict', 'getattrd', 'NoDefaultProvided',
            'get_current_apps', 'set_current_apps', 'OutputEventFilter',
@@ -503,7 +504,6 @@ def get_model_for_type(type):
     '''
     Return model class for a given type name.
     '''
-    from django.db.models import Q
     from django.contrib.contenttypes.models import ContentType
     for ct in ContentType.objects.filter(Q(app_label='main') | Q(app_label='auth', model='user')):
         ct_model = ct.model_class()
@@ -516,30 +516,31 @@ def get_model_for_type(type):
         raise DatabaseError('"{}" is not a valid AWX model.'.format(type))
 
 
-def cache_list_capabilities(page, prefetch_list, model, user):
+def prefetch_page_capabilities(model, page, prefetch_list, user):
     '''
-    Given a `page` list of objects, the specified roles for the specified user
-    are save on each object in the list, using 1 query for each role type
+    Given a `page` list of objects, a nested dictionary of user_capabilities
+    are returned by id, ex.
+    {
+        4: {'edit': True, 'start': True},
+        6: {'edit': False, 'start': False}
+    }
+    Each capability is produced for all items in the page in a single query
 
-    Examples:
-    capabilities_prefetch = ['admin', 'execute']
+    Examples of prefetch language:
+    prefetch_list = ['admin', 'execute']
       --> prefetch the admin (edit) and execute (start) permissions for
           items in list for current user
-    capabilities_prefetch = ['inventory.admin']
+    prefetch_list = ['inventory.admin']
       --> prefetch the related inventory FK permissions for current user,
           and put it into the object's cache
-    capabilities_prefetch = [{'copy': ['inventory.admin', 'project.admin']}]
+    prefetch_list = [{'copy': ['inventory.admin', 'project.admin']}]
       --> prefetch logical combination of admin permission to inventory AND
           project, put into cache dictionary as "copy"
     '''
-    from django.db.models import Q
     page_ids = [obj.id for obj in page]
+    mapping = {}
     for obj in page:
-        obj.capabilities_cache = {}
-
-    skip_models = []
-    if hasattr(model, 'invalid_user_capabilities_prefetch_models'):
-        skip_models = model.invalid_user_capabilities_prefetch_models()
+        mapping[obj.id] = {}
 
     for prefetch_entry in prefetch_list:
 
@@ -583,11 +584,9 @@ def cache_list_capabilities(page, prefetch_list, model, user):
 
         # Save data item-by-item
         for obj in page:
-            if skip_models and obj.__class__.__name__.lower() in skip_models:
-                continue
-            obj.capabilities_cache[display_method] = False
-            if obj.pk in ids_with_role:
-                obj.capabilities_cache[display_method] = True
+            mapping[obj.pk][display_method] = bool(obj.pk in ids_with_role)
+
+    return mapping
 
 
 def validate_vars_type(vars_obj):