Perhaps I’m just a bit dense but as per the docs JinjaTemplate() should take **kwargs (https://docs.prefect.io/api/unreleased/tasks/strings.html#jinjatemplate). Yet when I pass it keyword arguments it complains about super().__init__() getting unexpected keyword arguments. Bug?

What I understand from the source code, is that task initialization for

JinjaTemplate(Task)

only accepts generic task initialization

**kwargs

, not your formatting params. Formatting params, i.e.

**format_kwargs

are passed strictly at flow runtime, in other words

flow.run()

Ah, that makes sense!

From the comments in source code:

python
    from prefect import Flow
    from prefect.tasks.templates import JinjaTemplate
    message = '''
    Hi {{name}}!  Welcome to Prefect.  Today is {{today}}.
    '''
    msg_task = JinjaTemplate(name="message body", template=message)
    with Flow("string-template") as flow:
            output = msg_task(name="Marvin")
    flow_state = flow.run()
    print(flow_state.result[output].result)
    # Hi Marvin!  Welcome to Prefect.  Today is 2019-08-28.

I saw that. But my question wasn’t how to reference variables explicitly passed to

JinjaTemplate()

but how to reference variables from the context, which the docs say is possible

oh, my bad. Try the same key name in the jinja template. It looks like it works with

{{today}}

, since the today key is provided by the prefect context.