The Rows Exist step allows you to react to an empty input stream. It is useful if you’d like to react to inputs that are empty, such as a SQL query result containing no rows, a file being empty, or simply that a particular branch in your data flow did not see a single row.
The step has two output gates. If any rows arrive at the step, they are passed through the yes gate. If no rows arrive at the step, and all input steps supplying rows have signaled that they are done, the Rows Exist step generates a single row through its no gate with all fields set to nil.
You can then take care of any processing that needs to happen if there are no input rows at all.
The following example setup fails the flow if all input rows are filtered out as invalid.
Check out the following files for examples on how the flow operates depending on whether valid rows are present:
rows-exist.dfl (14.4 KB)
no-rows-exist.dfl (14.9 KB)