Execute dplyr operation only if column exists

Question

Drawing on the discussion on conditional dplyr evaluation I would like conditionally execute a step in pipeline depending on whether the reference column exists in the passed da

Answer 1

I know I'm late to the party, but here's an answer somewhat more in line with what you were originally thinking:

mtcars %>%
  filter(am == 1) %>%
  {
    if("cyl" %in% names(.)) filter(., cyl == 4) else .
  }

Basically, you were missing the . in filter. Note this is because the pipeline doesn't add . to filter(expr) since it is in an expression surrounded by {}.