Source code for airflow.providers.common.sql.sensors.sql
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from __future__ import annotations
from operator import itemgetter
from typing import TYPE_CHECKING, Any, Callable, Mapping, Sequence
from airflow.exceptions import AirflowException
from airflow.hooks.base import BaseHook
from airflow.providers.common.sql.hooks.sql import DbApiHook
from airflow.sensors.base import BaseSensorOperator
if TYPE_CHECKING:
from airflow.utils.context import Context
[docs]class SqlSensor(BaseSensorOperator):
"""
Run a SQL statement repeatedly until a criteria is met.
This will keep trying until success or failure criteria are met, or if the
first cell is not either ``0``, ``'0'``, ``''``, or ``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 the output
of selector as the only argument, and returns a boolean (optional).
:param failure: Failure criteria for the sensor is a Callable that takes the output
of selector as the only argument and returns a boolean (optional).
:param selector: Function which takes the resulting row and transforms it before
it is passed to success or failure (optional). Takes the first cell by default.
: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", "hook_params", "parameters")
[docs] template_ext: Sequence[str] = (".hql", ".sql")
def __init__(
self,
*,
conn_id: str,
sql: str,
parameters: Mapping[str, Any] | None = None,
success: Callable[[Any], bool] | None = None,
failure: Callable[[Any], bool] | None = None,
selector: Callable[[tuple[Any]], Any] = itemgetter(0),
fail_on_empty: bool = False,
hook_params: Mapping[str, Any] | None = None,
**kwargs,
) -> None:
self.conn_id = conn_id
self.sql = sql
self.parameters = parameters
self.success = success
self.failure = failure
self.selector = selector
self.fail_on_empty = fail_on_empty
self.hook_params = hook_params
super().__init__(**kwargs)
def _get_hook(self) -> DbApiHook:
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) -> bool:
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:
message = "No rows returned, raising as per fail_on_empty flag"
raise AirflowException(message)
else:
return False
condition = self.selector(records[0])
if self.failure is not None:
if callable(self.failure):
if self.failure(condition):
message = f"Failure criteria met. self.failure({condition}) returned True"
raise AirflowException(message)
else:
message = f"self.failure is present, but not callable -> {self.failure}"
raise AirflowException(message)
if self.success is not None:
if callable(self.success):
return self.success(condition)
else:
message = f"self.success is present, but not callable -> {self.success}"
raise AirflowException(message)
return bool(condition)