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cqlengine documentation

Users of versions < 0.16, the default keyspace 'cqlengine' has been removed. Please read this before upgrading: :ref:`Breaking Changes <keyspace-change>`

cqlengine is a Cassandra CQL 3 Object Mapper for Python

:ref:`getting-started`

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Contents:

Getting Started

#first, define a model
from cqlengine import columns
from cqlengine import Model

class ExampleModel(Model):
    example_id      = columns.UUID(primary_key=True, default=uuid.uuid4)
    example_type    = columns.Integer(index=True)
    created_at      = columns.DateTime()
    description     = columns.Text(required=False)

#next, setup the connection to your cassandra server(s)...
>>> from cqlengine import connection

# see http://datastax.github.io/python-driver/api/cassandra/cluster.html for options
# the list of hosts will be passed to create a Cluster() instance
>>> connection.setup(['127.0.0.1'], "cqlengine")

# if you're connecting to a 1.2 cluster
>>> connection.setup(['127.0.0.1'], "cqlengine", protocol_version=1)

#...and create your CQL table
>>> from cqlengine.management import sync_table
>>> sync_table(ExampleModel)

#now we can create some rows:
>>> em1 = ExampleModel.create(example_type=0, description="example1", created_at=datetime.now())
>>> em2 = ExampleModel.create(example_type=0, description="example2", created_at=datetime.now())
>>> em3 = ExampleModel.create(example_type=0, description="example3", created_at=datetime.now())
>>> em4 = ExampleModel.create(example_type=0, description="example4", created_at=datetime.now())
>>> em5 = ExampleModel.create(example_type=1, description="example5", created_at=datetime.now())
>>> em6 = ExampleModel.create(example_type=1, description="example6", created_at=datetime.now())
>>> em7 = ExampleModel.create(example_type=1, description="example7", created_at=datetime.now())
>>> em8 = ExampleModel.create(example_type=1, description="example8", created_at=datetime.now())

#and now we can run some queries against our table
>>> ExampleModel.objects.count()
8
>>> q = ExampleModel.objects(example_type=1)
>>> q.count()
4
>>> for instance in q:
>>>     print instance.description
example5
example6
example7
example8

#here we are applying additional filtering to an existing query
#query objects are immutable, so calling filter returns a new
#query object
>>> q2 = q.filter(example_id=em5.example_id)

>>> q2.count()
1
>>> for instance in q2:
>>>     print instance.description
example5

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