I must be missing something obvious. The documentation says

When writing an op, users can optionally provide a first parameter, context. When this parameter is supplied, Dagster will supply a context object to the body of the op.

I have a test asset defined with a test op:

@op
def test_op(context: OpExecutionContext, test: str) -> int:
    <http://context.log.info|context.log.info>(f"test op {test}")
    return 42

@asset
def test_asset() -> int:
    return test_op("test")

Materializing

test_asset

fails with:

dagster._core.errors.DagsterInvalidInvocationError: Compute function of op 'test_op' has context argument, but no context was provided when invoking.

What am I doing wrong here?

What happens if you modify the asset function definition to include

context

?

@asset
def test_asset(context: OpExecutionContext):
    return test_op("test") # might need to pass in context explicitly

Hi! Ops can't be executed within assets. The mental model is that the

@asset

decorator is: • trust this function will produce an asset • the function body is an Op that produces this asset So trying to execute an individual Op within that function body breaks that model. If you'd like to run a function within an

@asset

-decorated function, then you can remove the

@op

decorator and use the function as a normal python fn. If you'd like to run this Op on its own, you can write it in a job and execute that job. And in the advanced use cases, you may want to use Ops to produce assets. To get this granular control, you'd use the

@graph_asset

decorator instead of the

@asset

decorator

Thanks @Tim Castillo, knew I was misunderstanding something basic here.