Source code for airflow.sensors.sql
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from typing import Sequence
from airflow.exceptions import AirflowException
from airflow.hooks.base import BaseHook
from airflow.hooks.dbapi import DbApiHook
from airflow.sensors.base import BaseSensorOperator
from airflow.utils.context import Context
[docs]class SqlSensor(BaseSensorOperator):
"""
Runs a sql statement repeatedly until a criteria is met. It will keep trying until
success or failure criteria are met, or if the first cell is not in (0, '0', '', None).
Optional success and failure callables are called with the first cell returned as the argument.
If success callable is defined the sensor will keep retrying until the criteria is met.
If failure callable is defined and the criteria is met the sensor will raise AirflowException.
Failure criteria is evaluated before success criteria. A fail_on_empty boolean can also
be passed to the sensor in which case it will fail if no rows have been returned
:param conn_id: The connection to run the sensor against
:param sql: The sql to run. To pass, it needs to return at least one cell
that contains a non-zero / empty string value.
:param parameters: The parameters to render the SQL query with (optional).
:param success: Success criteria for the sensor is a Callable that takes first_cell
as the only argument, and returns a boolean (optional).
:param failure: Failure criteria for the sensor is a Callable that takes first_cell
as the only argument and return a boolean (optional).
:param fail_on_empty: Explicitly fail on no rows returned.
:param hook_params: Extra config params to be passed to the underlying hook.
Should match the desired hook constructor params.
"""
[docs] template_fields: Sequence[str] = ('sql',)
[docs] template_ext: Sequence[str] = (
'.hql',
'.sql',
)
def __init__(
self,
*,
conn_id,
sql,
parameters=None,
success=None,
failure=None,
fail_on_empty=False,
hook_params=None,
**kwargs,
):
self.conn_id = conn_id
self.sql = sql
self.parameters = parameters
self.success = success
self.failure = failure
self.fail_on_empty = fail_on_empty
self.hook_params = hook_params
super().__init__(**kwargs)
def _get_hook(self):
conn = BaseHook.get_connection(self.conn_id)
hook = conn.get_hook(hook_params=self.hook_params)
if not isinstance(hook, DbApiHook):
raise AirflowException(
f'The connection type is not supported by {self.__class__.__name__}. '
f'The associated hook should be a subclass of `DbApiHook`. Got {hook.__class__.__name__}'
)
return hook
[docs] def poke(self, context: Context):
hook = self._get_hook()
self.log.info('Poking: %s (with parameters %s)', self.sql, self.parameters)
records = hook.get_records(self.sql, self.parameters)
if not records:
if self.fail_on_empty:
raise AirflowException("No rows returned, raising as per fail_on_empty flag")
else:
return False
first_cell = records[0][0]
if self.failure is not None:
if callable(self.failure):
if self.failure(first_cell):
raise AirflowException(f"Failure criteria met. self.failure({first_cell}) returned True")
else:
raise AirflowException(f"self.failure is present, but not callable -> {self.failure}")
if self.success is not None:
if callable(self.success):
return self.success(first_cell)
else:
raise AirflowException(f"self.success is present, but not callable -> {self.success}")
return bool(first_cell)
