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Object Mapper
=============
cqlengine is the Cassandra CQL 3 Object Mapper packaged with this driver
:ref:`Jump to Getting Started <getting-started>`
Contents
--------
:doc:`cqlengine/upgrade_guide`
For migrating projects from legacy cqlengine, to the integrated product
:doc:`cqlengine/models`
Examples defining models, and mapping them to tables
:doc:`cqlengine/queryset`
Overview of query sets and filtering
:doc:`cqlengine/batches`
Working with batch mutations
:doc:`cqlengine/connections`
Working with multiple sessions
:ref:`API Documentation <om_api>`
Index of API documentation
:doc:`cqlengine/third_party`
High-level examples in Celery and uWSGI
:doc:`cqlengine/faq`
.. toctree::
:hidden:
cqlengine/upgrade_guide
cqlengine/models
cqlengine/queryset
cqlengine/batches
cqlengine/connections
cqlengine/third_party
cqlengine/faq
.. _getting-started:
Getting Started
---------------
.. code-block:: python
import uuid
from cassandra.cqlengine import columns
from cassandra.cqlengine import connection
from datetime import datetime
from cassandra.cqlengine.management import sync_table
from cassandra.cqlengine.models import Model
#first, define a 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)...
# 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", protocol_version=3)
#...and create your CQL 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
|
