vmware-nsx/neutron/openstack/common/db/sqlalchemy/utils.py
Mark McClain 380b0e7db6 Rename Quantum to Neutron
This change renames everything to Neutron while providing backwards
compatible adjustments for Grizzly configuration files.

implements blueprint: remove-use-of-quantum

Change-Id: Ie7d07ba7c89857e13d4ddc8f0e9b68de020a3d19
2013-07-06 15:02:43 -04:00

133 lines
4.8 KiB
Python

# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# Copyright 2010-2011 OpenStack Foundation.
# Copyright 2012 Justin Santa Barbara
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""Implementation of paginate query."""
import sqlalchemy
from neutron.openstack.common.gettextutils import _
from neutron.openstack.common import log as logging
LOG = logging.getLogger(__name__)
class InvalidSortKey(Exception):
message = _("Sort key supplied was not valid.")
# copy from glance/db/sqlalchemy/api.py
def paginate_query(query, model, limit, sort_keys, marker=None,
sort_dir=None, sort_dirs=None):
"""Returns a query with sorting / pagination criteria added.
Pagination works by requiring a unique sort_key, specified by sort_keys.
(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)
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 sort_keys: array of attributes by which results should be sorted
:param marker: the last item of the previous page; we returns the next
results after this value.
:param sort_dir: direction in which results should be sorted (asc, desc)
:param sort_dirs: per-column array of sort_dirs, corresponding to sort_keys
:rtype: sqlalchemy.orm.query.Query
:return: The query with sorting/pagination added.
"""
if 'id' not in sort_keys:
# TODO(justinsb): If this ever gives a false-positive, check
# the actual primary key, rather than assuming its id
LOG.warn(_('Id not in sort_keys; is sort_keys unique?'))
assert(not (sort_dir and sort_dirs))
# Default the sort direction to ascending
if sort_dirs is None and sort_dir is None:
sort_dir = 'asc'
# Ensure a per-column sort direction
if sort_dirs is None:
sort_dirs = [sort_dir for _sort_key in sort_keys]
assert(len(sort_dirs) == len(sort_keys))
# Add sorting
for current_sort_key, current_sort_dir in zip(sort_keys, sort_dirs):
sort_dir_func = {
'asc': sqlalchemy.asc,
'desc': sqlalchemy.desc,
}[current_sort_dir]
try:
sort_key_attr = getattr(model, current_sort_key)
except AttributeError:
raise InvalidSortKey()
query = query.order_by(sort_dir_func(sort_key_attr))
# Add pagination
if marker is not None:
marker_values = []
for sort_key in sort_keys:
v = getattr(marker, sort_key)
marker_values.append(v)
# Build up an array of sort criteria as in the docstring
criteria_list = []
for i in range(0, len(sort_keys)):
crit_attrs = []
for j in range(0, i):
model_attr = getattr(model, sort_keys[j])
crit_attrs.append((model_attr == marker_values[j]))
model_attr = getattr(model, sort_keys[i])
if sort_dirs[i] == 'desc':
crit_attrs.append((model_attr < marker_values[i]))
elif sort_dirs[i] == 'asc':
crit_attrs.append((model_attr > marker_values[i]))
else:
raise ValueError(_("Unknown sort direction, "
"must be 'desc' or 'asc'"))
criteria = sqlalchemy.sql.and_(*crit_attrs)
criteria_list.append(criteria)
f = sqlalchemy.sql.or_(*criteria_list)
query = query.filter(f)
if limit is not None:
query = query.limit(limit)
return query