Additional refactoring to use the QuerySequence wrapper, so that we can still

use len() and slicing on SQLAlchemy query results.  We also don't need to
list()-ify the results in the tests.  This isn't perfect, but at least it
doesn't introduce yet another layer violation.

4 files changed, 14 insertions, 21 deletions

diff --git a/src/mailman/rest/helpers.py b/src/mailman/rest/helpers.py
index a7bbc2bae..6a1408988 100644
--- a/src/mailman/rest/helpers.py
+++ b/src/mailman/rest/helpers.py
@@ -139,16 +139,14 @@ class CollectionMixin:
         return etag(resource)
 
     def _get_collection(self, request):
-        """Return the collection as a list-like object.
+        """Return the collection as a sequence.
 
-        The returned value must support iteration and slicing. It can for
-        example be a concrete list or an SQLAlchemy request.
-
-        This method must be implemented by subclasses.
+        The returned value must support the collections.abc.Sequence
+        API.  This method must be implemented by subclasses.
 
         :param request: An http request.
         :return: The collection
-        :rtype: list
+        :rtype: collections.abc.Sequence
         """
         raise NotImplementedError
 
@@ -165,12 +163,9 @@ class CollectionMixin:
         # get turned into HTTP 400 errors.
         count = request.get_param_as_int('count', min=0)
         page = request.get_param_as_int('page', min=1)
-        try:
-            total_size = collection.count()
-        except TypeError:
-            total_size = len(collection)
+        total_size = len(collection)
         if count is None and page is None:
-            return 0, total_size, list(collection)
+            return 0, total_size, collection
         list_start = (page - 1) * count
         list_end = page * count
         return list_start, total_size, collection[list_start:list_end]
diff --git a/src/mailman/rest/lists.py b/src/mailman/rest/lists.py
index 70f100f25..a4d2da56a 100644
--- a/src/mailman/rest/lists.py
+++ b/src/mailman/rest/lists.py
@@ -47,7 +47,6 @@ from mailman.rest.members import AMember, MemberCollection
 from mailman.rest.post_moderation import HeldMessages
 from mailman.rest.sub_moderation import SubscriptionRequests
 from mailman.rest.validator import Validator
-from sqlalchemy.orm.exc import NoResultFound, MultipleResultsFound
 from zope.component import getUtility
 
 
@@ -152,14 +151,12 @@ class AList(_ListBase):
         """Return a single member representation."""
         if self._mlist is None:
             return NotFound(), []
-        try:
-            the_member = getUtility(ISubscriptionService).find_members(
-                email, self._mlist.list_id, role).one()
-        except NoResultFound:
+        members = getUtility(ISubscriptionService).find_members(
+            email, self._mlist.list_id, role)
+        if len(members) == 0:
             return NotFound(), []
-        except MultipleResultsFound:
-            raise AssertionError('Too many matches')
-        return AMember(request.context['api_version'], the_member.member_id)
+        assert len(members) == 1, 'Too many matches'
+        return AMember(request.context['api_version'], members[0].member_id)
 
     @child(roster_matcher)
     def roster(self, request, segments, role):
diff --git a/src/mailman/rest/members.py b/src/mailman/rest/members.py
index b41afe18a..12a413f42 100644
--- a/src/mailman/rest/members.py
+++ b/src/mailman/rest/members.py
@@ -31,7 +31,7 @@ from mailman.interfaces.address import IAddress, InvalidEmailAddressError
 from mailman.interfaces.listmanager import IListManager
 from mailman.interfaces.member import (
     AlreadySubscribedError, DeliveryMode, MemberRole, MembershipError,
-    MembershipIsBannedError, MissingPreferredAddressError, NotAMemberError)
+    MembershipIsBannedError, MissingPreferredAddressError)
 from mailman.interfaces.registrar import IRegistrar
 from mailman.interfaces.subscriptions import (
     ISubscriptionService, RequestRecord, TokenOwner)
diff --git a/src/mailman/rest/post_moderation.py b/src/mailman/rest/post_moderation.py
index ca3e228ba..746503ba9 100644
--- a/src/mailman/rest/post_moderation.py
+++ b/src/mailman/rest/post_moderation.py
@@ -31,6 +31,7 @@ from mailman.rest.helpers import (
     CollectionMixin, bad_request, child, etag, no_content, not_found, okay,
     path_to)
 from mailman.rest.validator import Validator, enum_validator
+from mailman.utilities.queries import QuerySequence
 from zope.component import getUtility
 
 
@@ -148,7 +149,7 @@ class HeldMessages(_HeldMessageBase, CollectionMixin):
 
     def _get_collection(self, request):
         requests = IListRequests(self._mlist)
-        return requests.of_type(RequestType.held_message)
+        return QuerySequence(requests.of_type(RequestType.held_message))
 
     def on_get(self, request, response):
         """/lists/listname/held"""