def _get_limit_param(request, max_limit):
"""Extract integer limit from request or fail."""
try:
limit = int(request.GET.get('limit', 0))
if limit >= 0:
return limit
except ValueError:
pass
msg = _("Limit must be an integer 0 or greater and not '%d'")
raise exceptions.BadRequest(resource='limit', msg=msg)
def update(self, request, id, body=None, **kwargs):
"""Updates the specified entity's attributes."""
parent_id = kwargs.get(self._parent_id_name)
try:
payload = body.copy()
except AttributeError:
msg = _("Invalid format: %s") % request.body
raise exceptions.BadRequest(resource='body', msg=msg)
payload['id'] = id
self._notifier.info(request.context, self._resource + '.update.start',
payload)
body = Controller.prepare_request_body(request.context,
body,
False,
self._resource,
self._attr_info,
allow_bulk=self._allow_bulk)
action = self._plugin_handlers[self.UPDATE]
# Load object to check authz
# but pass only attributes in the original body and required
# by the policy engine to the policy 'brain'
field_list = [
name for (name, value) in (self._attr_info).items()
if (value.get('required_by_policy') or value.get('primary_key')
or 'default' not in value)
]
# Ensure policy engine is initialized
policy.init()
orig_obj = self._item(request,
id,
field_list=field_list,
parent_id=parent_id)
orig_obj.update(body[self._resource])
attribs = attributes.ATTRIBUTES_TO_UPDATE
orig_obj[attribs] = body[self._resource].keys()
try:
policy.enforce(request.context, action, orig_obj)
except exceptions.PolicyNotAuthorized:
# To avoid giving away information, pretend that it
# doesn't exist
msg = _('The resource could not be found.')
raise webob.exc.HTTPNotFound(msg)
obj_updater = getattr(self._plugin, action)
kwargs = {self._resource: body}
if parent_id:
kwargs[self._parent_id_name] = parent_id
obj = obj_updater(request.context, id, **kwargs)
result = {self._resource: self._view(request.context, obj)}
notifier_method = self._resource + '.update.end'
self._notifier.info(request.context, notifier_method, result)
return result
def paginate_query(query, model, limit, sorts, marker_obj=None):
"""Returns a query with sorting / pagination criteria added.
Pagination works by requiring a unique sort key, specified by sorts.
(If sort keys is not unique, then we risk looping through values.)
We use the last row in the previous page as the 'marker' for pagination.
So we must return values that follow the passed marker in the order.
With a single-valued sort key, this would be easy: sort_key > X.
With a compound-values sort key, (k1, k2, k3) we must do this to repeat
the lexicographical ordering:
(k1 > X1) or (k1 == X1 && k2 > X2) or (k1 == X1 && k2 == X2 && k3 > X3)
The reason of didn't use OFFSET clause was it don't scale, please refer
discussion at https://lists.launchpad.net/openstack/msg02547.html
We also have to cope with different sort directions.
Typically, the id of the last row is used as the client-facing pagination
marker, then the actual marker object must be fetched from the db and
passed in to us as marker.
:param query: the query object to which we should add paging/sorting
:param model: the ORM model class
:param limit: maximum number of items to return
:param sorts: array of attributes and direction by which results should
be sorted
:param marker: the last item of the previous page; we returns the next
results after this value.
:rtype: sqlalchemy.orm.query.Query
:return: The query with sorting/pagination added.
"""
if not sorts:
return query
# A primary key must be specified in sort keys
assert not (limit and len(
set(dict(sorts).keys())
& set(model.__table__.primary_key.columns.keys())) == 0)
# Add sorting
for sort_key, sort_direction in sorts:
sort_dir_func = sqlalchemy.asc if sort_direction else sqlalchemy.desc
try:
sort_key_attr = getattr(model, sort_key)
except AttributeError:
# Extension attribute doesn't support for sorting. Because it
# existed in attr_info, it will be catched at here
msg = _("%s is invalid attribute for sort_key") % sort_key
raise n_exc.BadRequest(resource=model.__tablename__, msg=msg)
if isinstance(sort_key_attr.property, RelationshipProperty):
msg = _("The attribute '%(attr)s' is reference to other "
"resource, can't used by sort "
"'%(resource)s'") % {
'attr': sort_key,
'resource': model.__tablename__
}
raise n_exc.BadRequest(resource=model.__tablename__, msg=msg)
query = query.order_by(sort_dir_func(sort_key_attr))
# Add pagination
if marker_obj:
marker_values = [getattr(marker_obj, sort[0]) for sort in sorts]
# Build up an array of sort criteria as in the docstring
criteria_list = []
for i, sort in enumerate(sorts):
crit_attrs = [(getattr(model, sorts[j][0]) == marker_values[j])
for j in moves.xrange(i)]
model_attr = getattr(model, sort[0])
if sort[1]:
crit_attrs.append((model_attr > marker_values[i]))
else:
crit_attrs.append((model_attr < marker_values[i]))
criteria = sqlalchemy.sql.and_(*crit_attrs)
criteria_list.append(criteria)
f = sqlalchemy.sql.or_(*criteria_list)
query = query.filter(f)
if limit:
query = query.limit(limit)
return query
