Append data to file

[Bargeton]

Hello,

I have a workflow which compute a table results.

I will execute this workflow daily (or weekly, or monthly).

I need to write the new computed results, merging it with the previous ones already written into a file.

It's not just an "append" to do, as the previous execution and the current one, may have overlap results.

So basically, I need to

- read the existing results file

- compute the new result (it's independant from reading the previous results).

- merge / join both results tables

  ** On left output of the join, I will have all previous results not in current ones

  ** On right output of the join, I will have all new results

  ** In middle output, it's the duplicated results

- then write left + middle + right to the file (overwritte the file).

This  is working well... if I already have an existing file.

But at the first execution, it bug as there is no existing file to feed the input/read module.

How can I acheive this?

Regards,

Alex

[David-Carnes]

@Bargeton 
Ok, here is one way; use a batch macro.

First,  use the Directory tool to see if the file exists.

Then let the macro decide which Container to destroy.

I've attached the two CSV files for the proof of concept.  Put them  somewhere and play  with  removing and returning the test.csv file.

I thought of a   way to do this in the R tool.  If you  want that,  say something in the comments.

David