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Data Processing & Logging​

When building a Robot Task that loops through a data file or list of records, two types of logging should be planned from the start:

  • Exception logging — records that could not be processed so they can be reviewed and corrected
  • Processing status logging — tracks which records completed successfully so you know exactly where things stand if a failure occurs mid-run

Planning for both means the process never has to stop on a single bad record, and you always have a clear picture of what was and wasn't processed.

Exception Logging​

An exception log captures records that fail or contain invalid data during the loop, rather than letting the process halt entirely.

General approach:

  1. Create an exceptions Excel workbook at the start of the task

    • Use a New Excel action to open the Excel application
    • Use an Attach to Excel action to set the context for subsequent Excel actions
    • Use a Create Workbook action to create a new workbook
    • Use Set Cell Value actions to write your column headers to the first row

  2. Inside the loop, wrap error-prone steps in an If statement

    • The If statement acts as a catch — evaluate whether the data is valid or whether an error condition exists
    • In the Then or Else block (whichever represents the error condition):
      • Use an Attach to Excel action to reconnect to the exceptions workbook
      • Use Set Cell Value actions to write the record's data and error details to the next row
      • Use a Continue Loop action as the last step in the block — this skips the rest of the current iteration and moves to the next record without stopping the process

  3. At the end of the task, save and close the exceptions workbook

    • Use an Attach to Excel action
    • Use a Save as Workbook action to save to a file path or clipboard
    • Use a Close Workbook action
    • Use a Quit Excel action

The Continue Loop action is what makes exception handling work cleanly in a loop. It allows the process to skip a problem record, log it, and keep moving — rather than stopping entirely or retrying the same record.

Processing Status Logging​

A status log tracks which records have been fully processed. If the job fails partway through, you can see exactly which records completed and which did not.

General approach:

  1. Add a Status column to your List Variable after loading the data file

    • After loading the data file as a List Variable, use a Column - Create action to append a new column (e.g., Status) to the list

  2. At the end of the loop body, mark the record as processed

    • Use a List - Set Value action to write a value like Processed to the Status column for the current row
    • Because this is the last step in the loop, a record only gets marked as processed if every previous step in the iteration completed successfully

  3. Save the list regularly

    • Use a List - Save action at key points (end of each iteration, or at the end of the task) to write the list — including the Status column — to a file or clipboard
    • This gives you a persistent record of what was processed even if the task fails before completing

Combining Both Approaches​

Using both logs together gives you complete coverage:

  • The exception log tells you which records had bad data or triggered errors
  • The status log tells you which records ran to completion

Records that appear in neither log after a failure indicate where the process stopped unexpectedly and can be used to determine where to resume.