j-martin / cqlengine

Cassandra CQL 3 Object Mapper for Python

cqlengine

cqlengine is a Cassandra CQL 3 Object Mapper for Python

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

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Installation

pip install cqlengine

Getting Started on your local machine

#first, define a model
import uuid
from cqlengine import columns
from cqlengine.models import Model

class ExampleModel(Model):
    read_repair_chance = 0.05 # optional - defaults to 0.1
    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) and the default keyspace...
>>> from cqlengine import connection
>>> connection.setup(['127.0.0.1'], "cqlengine")

# or if you're still on cassandra 1.2
>>> connection.setup(['127.0.0.1'], "cqlengine", protocol_version=1)

# create your keyspace.  This is, in general, not what you want in production
# see https://cassandra.apache.org/doc/cql3/CQL.html#createKeyspaceStmt for options
>>> from cqlengine.management import create_keyspace
>>> create_keyspace("cqlengine", "SimpleStrategy", 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

Contributing

If you'd like to contribute to cqlengine, please read the contributor guidelines

Authors

cqlengine was developed primarily by (Blake Eggleston)blakeeggleston and Jon Haddad, with contributions from several others in the community.