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Amit Singh
03/23/2020, 3:27 PM@here I'm getting the following error when calling a task from a test case in pytest. Any clues. thanks
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flow = flow or prefect.context.get("flow", None)
if not flow:
> raise ValueError("Could not infer an active Flow context.")
E ValueError: Could not infer an active Flow context.j
josh
03/23/2020, 3:28 PMHey @Amit Singh how are you calling the task? You may need to use the task’s
.run()e.g.:
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In [2]: @task
...: def a():
...: print(5)
...:
In [3]: a()
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-17-8d7b4527e81d> in <module>
----> 1 a()
~/Desktop/code/prefect/src/prefect/core/task.py in __call__(self, mapped, task_args, upstream_tasks, flow, *args, **kwargs)
395 new = self.copy(**(task_args or {}))
396 new.bind(
--> 397 *args, mapped=mapped, upstream_tasks=upstream_tasks, flow=flow, **kwargs
398 )
399 return new
~/Desktop/code/prefect/src/prefect/core/task.py in bind(self, mapped, upstream_tasks, flow, *args, **kwargs)
447 flow = flow or prefect.context.get("flow", None)
448 if not flow:
--> 449 raise ValueError("Could not infer an active Flow context.")
450
451 self.set_dependencies(
ValueError: Could not infer an active Flow context.
In [4]: a.run()
5c
Chris White
03/23/2020, 3:29 PM
Calling a task instance attempts to bind keyword dependencies, so calling a task instance can only occur when there is a known flow to track those dependencies; calling
task.runa
Amit Singh
03/23/2020, 3:31 PMI have defined defined the task in a like this
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@task(name='create_athena_table_from_file_task')
def create_athena_table_from_file()c
Chris White
03/23/2020, 3:31 PM
this behavior isn’t related to your task definition
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Amit Singh
03/23/2020, 3:31 PMAnd calling it from pytest like this
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response = sm_lib.athena_wrapper.create_athena_table_from_file(**temp_params)c
Chris White
03/23/2020, 3:32 PM
see what i said above about calling a task instance
(and josh’s great example)
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Amit Singh
03/23/2020, 3:35 PMGot it. but i think .run is called only when the task is defined as a class, while i have created a task function here
@Chris White @josh
c
Chris White
03/23/2020, 3:36 PM
the task decorator is just a convenience for creating a Task class and instantiating it for you, so your
create_athena_table_from_fileand so it also has a run method
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Amit Singh
03/23/2020, 3:38 PMThanks a lot guys. It worked
💯 2
c
Chris White
03/23/2020, 3:38 PM
awesome - anytime!