There is a point in the docs about providing inputs to an op that made me stop:

An op only starts to execute once all of its inputs have been resolved. Inputs can be resolved in two ways:

• The upstream output that the input depends on has been successfully emitted and stored.

• The input was stubbed through config.

https://docs.dagster.io/concepts/ops-jobs-graphs/ops#inputs How does one “stub” an input “through config”? Is it somehow possible to have a simple op

@op
def my_op(my_input:str):
    # do something with my_input
    # ...

and provide

my_input

through a Pythonic config object without having to do something like this:

@op(ins={"my_input": In(Optional[str], default_value=None)})
def my_op(config: MyConfig, my_input:str | None = None):
    my_input = my_input if my_input is not None else config.configured_input

I wouldn’t consider the latter as “stubbing” the input, given that all the gymnastics around finding the actual value is done in the body of the function. Am I missing something here?

If you want a simple add a parameter to an op, you can do that. If you’re going to do a MyConfig, I don’t see why you wouldn’t add

my_input

to that. Here’s an example op with an array of Outputs passed to it

@op(ins={"start": In(Nothing)})
def OrderPipeline(context, nums: List[Output]):
    shell_script_runner(context, "MyOrderPipeline.ksh")

Hi Andras, The “stubbing” being referred to here is using the “inputs” field for an op on the run config schema:

from dagster import job, op

@op
def foo(a: int) -> int:
    return a + 1

@job
def foo_job():
    foo()

foo_job.execute_in_process(
    run_config={"ops": {"foo": {"inputs": {"a": 1}}}}
)

I realize the terminology is confusing, but this is separate from the “config” for the op, (i.e. what the op’s config schema defines).

Hi @sean, totally makes sense, thanks! Can I contribute to the docs to clarify this?

Thanks for the offer, but it’s such a small change that it’s not worth the overhead of a community PR, so I created a PR that links to the right place: https://github.com/dagster-io/dagster/pull/14991

👍