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from airflow.contrib.hooks.cassandra_hook import CassandraHook
from airflow.sensors.base_sensor_operator import BaseSensorOperator
from airflow.utils.decorators import apply_defaults
[docs]class CassandraTableSensor(BaseSensorOperator):
"""
Checks for the existence of a table in a Cassandra cluster.
For example, if you want to wait for a table called 't' to be created
in a keyspace 'k', instantiate it as follows:
>>> cassandra_sensor = CassandraTableSensor(table="k.t",
... cassandra_conn_id="cassandra_default",
... task_id="cassandra_sensor")
"""
[docs] template_fields = ('table',)
@apply_defaults
def __init__(self, table, cassandra_conn_id, *args, **kwargs):
"""
Create a new CassandraTableSensor
:param table: Target Cassandra table.
Use dot notation to target a specific keyspace.
:type table: str
:param cassandra_conn_id: The connection ID to use
when connecting to Cassandra cluster
:type cassandra_conn_id: str
"""
super(CassandraTableSensor, self).__init__(*args, **kwargs)
self.cassandra_conn_id = cassandra_conn_id
self.table = table
[docs] def poke(self, context):
self.log.info('Sensor check existence of table: %s', self.table)
hook = CassandraHook(self.cassandra_conn_id)
return hook.table_exists(self.table)