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# Authors:
# Jason Gerard DeRose <jderose@redhat.com>
#
# Copyright (C) 2008 Red Hat
# see file 'COPYING' for use and warranty information
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation; version 2 only
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
"""
Base classes for standard CRUD operations.
"""
import backend, frontend, errors
class Add(frontend.Method):
def get_args(self):
yield self.obj.primary_key
for arg in self.takes_args:
yield arg
def get_options(self):
for param in self.obj.params_minus_pk():
yield param
for option in self.takes_options:
yield option
class Get(frontend.Method):
def get_args(self):
yield self.obj.primary_key
class Del(frontend.Method):
def get_args(self):
yield self.obj.primary_key
class Mod(frontend.Method):
def get_args(self):
yield self.obj.primary_key
def get_options(self):
for param in self.obj.params_minus_pk():
yield param.__clone__(required=False)
class Find(frontend.Method):
def get_args(self):
yield self.obj.primary_key
def get_options(self):
for param in self.obj.params_minus_pk():
yield param.__clone__(required=False)
class CrudBackend(backend.Backend):
"""
Base class defining generic CRUD backend API.
"""
def create(self, **kw):
"""
Create a new entry.
This method should take key word arguments representing the
attributes the created entry will have.
If this methods constructs the primary_key internally, it should raise
an exception if the primary_key was passed. Likewise, if this method
requires the primary_key to be passed in from the caller, it should
raise an exception if the primary key was *not* passed.
This method should return a dict of the exact entry as it was created
in the backing store, including any automatically created attributes.
"""
raise NotImplementedError('%s.create()' % self.name)
def retrieve(self, primary_key, attributes):
"""
Retrieve an existing entry.
This method should take a two arguments: the primary_key of the
entry in question and a list of the attributes to be retrieved.
If the list of attributes is None then all non-operational
attributes will be returned.
If such an entry exists, this method should return a dict
representing that entry. If no such entry exists, this method
should return None.
"""
raise NotImplementedError('%s.retrieve()' % self.name)
def update(self, primary_key, **kw):
"""
Update an existing entry.
This method should take one required argument, the primary_key of the
entry to modify, plus optional keyword arguments for each of the
attributes being updated.
This method should return a dict representing the entry as it now
exists in the backing store. If no such entry exists, this method
should return None.
"""
raise NotImplementedError('%s.update()' % self.name)
def delete(self, primary_key):
"""
Delete an existing entry.
This method should take one required argument, the primary_key of the
entry to delete.
"""
raise NotImplementedError('%s.delete()' % self.name)
def search(self, **kw):
"""
Return entries matching specific criteria.
This method should take keyword arguments representing the search
criteria. If a key is the name of an entry attribute, the value
should be treated as a filter on that attribute. The meaning of
keys outside this namespace is left to the implementation.
This method should return and iterable containing the matched
entries, where each entry is a dict. If no entries are matched,
this method should return an empty iterable.
"""
raise NotImplementedError('%s.search()' % self.name)
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