How to pass a variable along the pipeline?
I have a pipeline that looks like this:
The Snaps are:
List all files in a given Box directory
Filter the files according to a mask
Read the matching Excel file into the pipeline
Con...
Forum Discussion
The best approach here would be to use a child pipeline to execute on each file to be read. That way the pipeline is only ever dealing with a single structure.
Where is this parameter coming from? Can you describe the scenario a little more?
Correct, there is no way to pass a variable “up”. To elaborate on that a bit, the snaps all run in parallel, so there would be a race between the snap that is passing the variable “up” and the snap that is trying to read the variable. For example, if there were two files coming in, the Write snap might see the first file name in one execution and the second file name in another execution.
I can see how that would happen, but could that not be controlled with a ForEach Snap that serializes the processing?
The use case you are thinking of would require a child pipeline due to the race condition, however it is not a requirement for the pipeline I am developing as (a) there will only be one file, and (b) it is acceptable to stop processing and throw an error if there is more than one file.
Hmm, I’m not quite sure what you mean here. The PipeExec snap basically obsoletes the ForEach snap.
That’s not going to be true in the general case. So, we can’t add something so error prone and hope that people only use it in the right situations.
