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 shutdown-fix

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example_mapper.py

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#!/usr/bin/env python

# Copyright 2013-2016 DataStax, Inc.

#

# 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.

# silence warnings just for demo -- applications would typically not do this

import os

os.environ['CQLENG_ALLOW_SCHEMA_MANAGEMENT'] = '1'

import logging

log = logging.getLogger()

log.setLevel('INFO')

handler = logging.StreamHandler()

handler.setFormatter(logging.Formatter("%(asctime)s [%(levelname)s] %(name)s: %(message)s"))

log.addHandler(handler)

from uuid import uuid4

from cassandra.cqlengine import columns

from cassandra.cqlengine import connection

from cassandra.cqlengine import management

from cassandra.cqlengine import ValidationError

from cassandra.cqlengine.models import Model

from cassandra.cqlengine.query import BatchQuery, LWTException

KEYSPACE = "testkeyspace"

class FamilyMembers(Model):

__keyspace__ = KEYSPACE

id = columns.UUID(primary_key=True, default=uuid4)

surname = columns.Text(primary_key=True)

name = columns.Text(primary_key=True)

birth_year = columns.Integer()

sex = columns.Text(min_length=1, max_length=1)

def validate(self):

super(FamilyMembers, self).validate()

if self.sex and self.sex not in 'mf':

raise ValidationError("FamilyMember.sex must be one of ['m', 'f']")

if self.birth_year and self.sex == 'f':

raise ValidationError("FamilyMember.birth_year is set, and 'a lady never tells'")

def main():

connection.default()

# Management functions would normally be used in development, and possibly for deployments.

# They are typically not part of a core application.

log.info("### creating keyspace...")

management.create_keyspace_simple(KEYSPACE, 1)

log.info("### syncing model...")

management.sync_table(FamilyMembers)

# default uuid is assigned

simmons = FamilyMembers.create(surname='Simmons', name='Gene', birth_year=1949, sex='m')

# add members to his family later

FamilyMembers.create(id=simmons.id, surname='Simmons', name='Nick', birth_year=1989, sex='m')

sophie = FamilyMembers.create(id=simmons.id, surname='Simmons', name='Sophie', sex='f')

nick = FamilyMembers.objects(id=simmons.id, surname='Simmons', name='Nick')

try:

nick.iff(birth_year=1988).update(birth_year=1989)

except LWTException:

print "precondition not met"

# showing validation

try:

FamilyMembers.create(id=simmons.id, surname='Tweed', name='Shannon', birth_year=1957, sex='f')

except ValidationError:

log.exception('INTENTIONAL VALIDATION EXCEPTION; Failed creating instance:')

FamilyMembers.create(id=simmons.id, surname='Tweed', name='Shannon', sex='f')

log.info("### add multiple as part of a batch")

# If creating many at one time, can use a batch to minimize round-trips

hogan_id = uuid4()

with BatchQuery() as b:

FamilyMembers.batch(b).create(id=hogan_id, surname='Hogan', name='Hulk', sex='m')

FamilyMembers.batch(b).create(id=hogan_id, surname='Hogan', name='Linda', sex='f')

FamilyMembers.batch(b).create(id=hogan_id, surname='Hogan', name='Nick', sex='m')

FamilyMembers.batch(b).create(id=hogan_id, surname='Hogan', name='Brooke', sex='f')

log.info("### All members")

for m in FamilyMembers.all():

print m, m.birth_year, m.sex

log.info("### Select by partition key")

for m in FamilyMembers.objects(id=simmons.id):

print m, m.birth_year, m.sex

log.info("### Constrain on clustering key")

for m in FamilyMembers.objects(id=simmons.id, surname=simmons.surname):

print m, m.birth_year, m.sex

log.info("### Constrain on clustering key")

kids = FamilyMembers.objects(id=simmons.id, surname=simmons.surname, name__in=['Nick', 'Sophie'])

log.info("### Delete a record")

FamilyMembers(id=hogan_id, surname='Hogan', name='Linda').delete()

for m in FamilyMembers.objects(id=hogan_id):

print m, m.birth_year, m.sex

management.drop_keyspace(KEYSPACE)

if __name__ == "__main__":

main()