I am getting `'FunctionTask' object is not iterable` error. Can anyone point me out, what it is?

Akshay Verma

08/19/2019, 1:04 PM

I am getting

'FunctionTask' object is not iterable

error. Can anyone point me out, what it is?

Jeremiah

08/19/2019, 1:05 PM

Hi @Akshay Verma, it sounds like you are trying to iterate over a task (or possibly the result of calling a task, which is also a task). Hard to say without more code - can you provide an example?

Akshay Verma

08/19/2019, 1:11 PM

i am doing the following:

Copy code

@task
def generate_context_level_data(mlsi, lvnr, tol):
    ml, ci = td_split_clv(mlsi, lvnr, tol)
    return ml, ci

td_input = {'a': 1, 'b': 2, 'c': 3}
with Flow('TD') as flow:
    td_input = Parameter("td_input")
    context_level_ml, context_level_ci = generate_context_level_data(td_input['a'],
                                                 td_input['b'],
                                                 td_input['c'])

Jeremiah

08/19/2019, 1:12 PM

Ah ok, it’s because you are assigning the result of

generate_context_level_data

to two variables (

context_level_ml

and

context_level_ci

), but Prefect doesn’t know what the result of

generate_context_level_data

is, so Python can’t do that unpacking.

Jeremiah

08/19/2019, 1:12 PM

Try this instead:

Jeremiah

08/19/2019, 1:12 PM

Copy code

context_result = generate_context_level_data(...)
context_level_ml = context_result[0]
context_level_ci = context_result[1]

Jeremiah

08/19/2019, 1:13 PM

Python will let us index an unknown object like

context_result

, but not unpack it.

Jeremiah

08/19/2019, 1:14 PM

(Note, I can’t promise this will work exactly as written because it depends on what is actually coming out of

generate_context_level_data

but this pattern should work — return a single object from your task, then index it appropriately)

Akshay Verma

08/19/2019, 1:22 PM

ahhh, will try that thanks

Jeremiah

08/19/2019, 1:23 PM

@Marvin archive “Error unpacking task: `'FunctionTask' object is not iterable`”

Jeremiah

08/19/2019, 1:23 PM

@Chris White some help 😉

Akshay Verma

08/19/2019, 1:47 PM

@Jeremiah thanks, that helps! Then I have to make sure what get passed around between

task

Chris White

08/19/2019, 6:13 PM

@Marvin archive “Error unpacking task: `'FunctionTask' object is not iterable`”

Marvin

08/19/2019, 6:13 PM

https://github.com/PrefectHQ/prefect/issues/1380

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