Howdy Rafael. It's not so hard. here's something like my folder structure,
using the datastax driver:
/www/mywebsite/cassandraconnection/simpleclient.py
# datastax imports
class SimpleClient():
session = None
def connect(self, nodes, certificate):
# some certification stuff here
cluster = Cluster(nodes, protocol_version=2, cql_version='3.1.7',
port=9042, ssl_options=ssl_options)
self.session = cluster.connect()
self.session.row_factory = dict_factory
# i like using the dict_factory - check out the other options if
you want though.
# but if you don't use the dict_factory then you might have to zip
your own results from cassandra, and results will be formatted in different
ways - that is, a single row will return as a list of dict items iirc,
while multiple rows will return as a list of dicts, but that list is the
first item of a list ( a list wtihin a list).. just kind of awkward results
def close(self):
self.session.cluster.shutdown()
self.session.shutdown()
log.info('Connection closed.')
/www/mywebsite/pyramidstuff/models.py
from cassandraconnection import SimpleClient
Session = SimpleClient()
# because this is imported into the __init__.py, this creates the
SimpleClient() object when your code runs - but note that it does not
connect yet - it just sits there
/www/mywebsite/pyramidstuff/__init__.py
# import the SimpleClient code to expose it
from cassandraconnection import SimpleClient
# import the simple client object
from .models import Session
# because i use uwsgi, i run multiple 'forks' of cassandra. if you don't
fork here, you'll have clashes between your multiple instances of a single
connection to the database clashing. this step in effect creates a separate
connection for each client
from uwsgidecorators import *
@postfork
def connect_cassandra_client():
CaSession.connect(['127.0.0.1'], certificate='/path/here')
print("connection to cassandra made")
# the new version of cassandra highly recommends a clean shutdown, i think
import atexit
@atexit.register
def shutdown_cassandra_client():
Session.close()
print("cassandra conn closed")
having said all that, the new version of cqlengine uses the datastax driver
as a backend, which might be a lot easier to work with - they made that
change in june/july iirc. However, Cassandra updates very, very often, and
I'm doing some unique stuff with it, so I chose not to use cqlengine,
although chances are it's what you want to use.
Oh actually the crummy part is waitress doesn't work well with the datastax
driver for some reason - you'll probably get weird errors and disconects.
I changed to nginx + uwsgi, which isn't very hard to do at all with
pyramid. In the simplest case, set up nginx, and just add a [uwsgi]
section to your development.ini with the necessary things, and use:
$VENV/bin/pip install uwsgi
$VENV/bin/uwsgi --ini-paste /www/mywebsite/pyramidstuff/development.ini
I'm writing parts of this off memory, and trying to summarize the code I am
looking at, so excuse my mistakes please, but it should give you an idea of
a method that works.
use from .models import Session to access the connection, and from there I
either write code in classes which write directly to cassandra, or for a
select few functions I import SimpleClient.py to do like simpler things. I
have to go so I can't finish this gl tho
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