60 строки
2.2 KiB
Python
60 строки
2.2 KiB
Python
# Licensed to the Apache Software Foundation (ASF) under one
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# or more contributor license agreements. See the NOTICE file
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# distributed with this work for additional information
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# regarding copyright ownership. The ASF licenses this file
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# to you under the Apache License, Version 2.0 (the
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# "License"); you may not use this file except in compliance
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# with the License. You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing,
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# software distributed under the License is distributed on an
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# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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# KIND, either express or implied. See the License for the
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# specific language governing permissions and limitations
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# under the License.
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from typing import Any, Dict, Optional
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from airflow.exceptions import AirflowException
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class DagParam:
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"""
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Class that represents a DAG run parameter.
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It can be used to parameterize your dags. You can overwrite its value by setting it on conf
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when you trigger your DagRun.
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This can also be used in templates by accessing {{context.params}} dictionary.
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**Example**:
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with DAG(...) as dag:
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EmailOperator(subject=dag.param('subject', 'Hi from Airflow!'))
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:param current_dag: Dag being used for parameter.
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:type current_dag: airflow.models.DAG
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:param name: key value which is used to set the parameter
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:type name: str
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:param default: Default value used if no parameter was set.
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:type default: Any
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"""
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def __init__(self, current_dag, name: str, default: Optional[Any] = None):
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if default:
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current_dag.params[name] = default
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self._name = name
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self._default = default
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def resolve(self, context: Dict) -> Any:
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"""Pull DagParam value from DagRun context. This method is run during ``op.execute()``."""
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default = self._default
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if not self._default:
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default = context['params'].get(self._name, None)
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resolved = context['dag_run'].conf.get(self._name, default)
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if not resolved:
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raise AirflowException(f'No value could be resolved for parameter {self._name}')
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return resolved
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