气流:在下一个任务中获取上一个任务 ID [英] Airflow: Get previous task id in the next task

问题描述

我有 2 个任务.在第一个中，python 运算符计算一些东西，在第二个中，我想在 Http 运算符中使用 python 运算符的输出.这是我的代码:

I have 2 tasks. In the first, python operator computes something and in the second I want to use the output of the python operator in the Http operator. Here is my code:

source_list = ['account', 'sales']

for source_type in source_list:
    t2 = PythonOperator(
                task_id='compute_next_gather_time_for_' + source_type,
                python_callable=compute_next_gather_time,
                provide_context=True,
                trigger_rule=TriggerRule.ALL_SUCCESS,
                op_args=[source_type],
                retries=3
            )

    t3 = SimpleHttpOperator(
                task_id='request_' + source_type + '_report',
                method='POST',
                http_conn_id='abc',
                endpoint=endpoint,
                data=json.dumps({
                    "query": {
                        "start": "{{ task_instance.xcom_pull(task_ids='prev_task_id') }}",
                        "stop": str(yesterday),
                        "fields": [
                            1
                        ]
                    }
                }),
                headers={"Content-Type": "application/json", "Authorization": 'abc'},
                response_check=lambda response: True if len(response.json()) == 0 else False,
                log_response=True,
                retries=3
            )

查询:我想在其数据变量中传递 t3 中的先前任务 ID.我不知道该怎么做，因为 t2 任务 id 不是恒定的.它随着 source_type 的变化而变化.显然，当我尝试它时并没有呈现它.

Query: I want to pass previous task id in t3 in its data variable. I am not sure how to do that since t2 task id is not constant. It changes with changing source_type. Evidently, when I tried it did not render it.

推荐答案

我之前没有在我的任何 DAG 中使用过 Jinja 模板，但是我遇到了类似的问题，我需要从特定的对象中检索 XCOM 值具有动态生成的 task_id 的任务.

I haven't used Jinja templating in any of my DAGs before, but I have been faced with similar problems where I was needing to retrieve XCOM values from a particular task that has a dynamically generated task_id.

您可以按照在 T2 中定义 task_id 的相同方式在 T3 中定义 task_ids.例如:

You could define the task_ids in T3 in the same way you defined the task_id in T2. For example:

source_list = ['account', 'sales']

for source_type in source_list:

    task_id='compute_next_gather_time_for_' + source_type

    t2 = PythonOperator(
                task_id=task_id,
                python_callable=compute_next_gather_time,
                provide_context=True,
                trigger_rule=TriggerRule.ALL_SUCCESS,
                op_args=[source_type],
                retries=3
            )

    t3 = SimpleHttpOperator(
                task_id='request_' + source_type + '_report',
                method='POST',
                http_conn_id='abc',
                endpoint=endpoint,
                data=json.dumps({
                    "query": {
                        "start": "{{ task_instance.xcom_pull(task_ids=task_id) }}",
                        "stop": str(yesterday),
                        "fields": [
                            1
                        ]
                    }
                }),
                headers={"Content-Type": "application/json", "Authorization": 'abc'},
                response_check=lambda response: True if len(response.json()) == 0 else False,
                log_response=True,
                retries=3
            )

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