124 lines
4.5 KiB
Python
Executable File
124 lines
4.5 KiB
Python
Executable File
#!/usr/bin/env python
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# Copyright 2013-2017 DataStax, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# silence warnings just for demo -- applications would typically not do this
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import os
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os.environ['CQLENG_ALLOW_SCHEMA_MANAGEMENT'] = '1'
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import logging
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log = logging.getLogger()
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log.setLevel('INFO')
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handler = logging.StreamHandler()
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handler.setFormatter(logging.Formatter("%(asctime)s [%(levelname)s] %(name)s: %(message)s"))
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log.addHandler(handler)
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from uuid import uuid4
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from cassandra.cqlengine import columns
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from cassandra.cqlengine import connection
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from cassandra.cqlengine import management
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from cassandra.cqlengine import ValidationError
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from cassandra.cqlengine.models import Model
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from cassandra.cqlengine.query import BatchQuery, LWTException
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KEYSPACE = "testkeyspace"
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class FamilyMembers(Model):
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__keyspace__ = KEYSPACE
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id = columns.UUID(primary_key=True, default=uuid4)
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surname = columns.Text(primary_key=True)
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name = columns.Text(primary_key=True)
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birth_year = columns.Integer()
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sex = columns.Text(min_length=1, max_length=1)
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def validate(self):
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super(FamilyMembers, self).validate()
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if self.sex and self.sex not in 'mf':
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raise ValidationError("FamilyMember.sex must be one of ['m', 'f']")
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if self.birth_year and self.sex == 'f':
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raise ValidationError("FamilyMember.birth_year is set, and 'a lady never tells'")
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def main():
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connection.default()
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# Management functions would normally be used in development, and possibly for deployments.
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# They are typically not part of a core application.
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log.info("### creating keyspace...")
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management.create_keyspace_simple(KEYSPACE, 1)
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log.info("### syncing model...")
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management.sync_table(FamilyMembers)
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# default uuid is assigned
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simmons = FamilyMembers.create(surname='Simmons', name='Gene', birth_year=1949, sex='m')
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# add members to his family later
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FamilyMembers.create(id=simmons.id, surname='Simmons', name='Nick', birth_year=1989, sex='m')
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sophie = FamilyMembers.create(id=simmons.id, surname='Simmons', name='Sophie', sex='f')
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nick = FamilyMembers.objects(id=simmons.id, surname='Simmons', name='Nick')
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try:
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nick.iff(birth_year=1988).update(birth_year=1989)
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except LWTException:
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print "precondition not met"
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log.info("### setting individual column to NULL by updating it to None")
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nick.update(birth_year=None)
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# showing validation
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try:
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FamilyMembers.create(id=simmons.id, surname='Tweed', name='Shannon', birth_year=1957, sex='f')
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except ValidationError:
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log.exception('INTENTIONAL VALIDATION EXCEPTION; Failed creating instance:')
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FamilyMembers.create(id=simmons.id, surname='Tweed', name='Shannon', sex='f')
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log.info("### add multiple as part of a batch")
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# If creating many at one time, can use a batch to minimize round-trips
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hogan_id = uuid4()
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with BatchQuery() as b:
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FamilyMembers.batch(b).create(id=hogan_id, surname='Hogan', name='Hulk', sex='m')
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FamilyMembers.batch(b).create(id=hogan_id, surname='Hogan', name='Linda', sex='f')
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FamilyMembers.batch(b).create(id=hogan_id, surname='Hogan', name='Nick', sex='m')
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FamilyMembers.batch(b).create(id=hogan_id, surname='Hogan', name='Brooke', sex='f')
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log.info("### All members")
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for m in FamilyMembers.all():
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print m, m.birth_year, m.sex
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log.info("### Select by partition key")
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for m in FamilyMembers.objects(id=simmons.id):
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print m, m.birth_year, m.sex
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log.info("### Constrain on clustering key")
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for m in FamilyMembers.objects(id=simmons.id, surname=simmons.surname):
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print m, m.birth_year, m.sex
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log.info("### Constrain on clustering key")
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kids = FamilyMembers.objects(id=simmons.id, surname=simmons.surname, name__in=['Nick', 'Sophie'])
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log.info("### Delete a record")
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FamilyMembers(id=hogan_id, surname='Hogan', name='Linda').delete()
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for m in FamilyMembers.objects(id=hogan_id):
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print m, m.birth_year, m.sex
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management.drop_keyspace(KEYSPACE)
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if __name__ == "__main__":
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main()
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