In Palantir Foundry, how can I detect whether my Transform is running in a Preview?

Question

I have a PySpark Transform that makes an API call, causing external side-effects. Because Preview runs on a sample of the input rows, previewing the transform causes bad API calls to be made.

Is there a way to detect whether my transform is running in Preview, so that I can avoid making the API calls in that case?

My code so far:

from transforms.api import transform_df, Input, incremental


@incremental()
@transform_df(
    df=Input("my_input")
)
def compute(df):
    return make_api_call(df)

Answer 1

You can check something like this from within your transform code:

from transforms.api import TransformContext

def is_preview(ctx: TransformContext) -> bool:
    return ctx.__class__.__name__ in {
        "PreviewTransformContext",
        "IncrementalPreviewTransformContext",
    }