How can I upsert a datatable current numeric value

Questions
1

Describe the problem/error/question

i do have a simple workflow that reads my gmail and aggretates email by number of occurences, and the idea is to store them in a datatable.

The datatable just holds : email, total_ocurrences.

When the email is not present, it just upserts the column total_ocurrences with the incoming value from the previous node, json.total_ocurrences, for the same given email.

But when the email is already present, the upsert must read the current row total_ocurrences and increase it by the incoming json.total_ocurrences.

I haven’t found any mean to read current datatable row column, ¿ how can it be read ?

What is the error message (if any)? None,

Please share your workflow

Share the output returned by the last node

Information on your n8n setup

  • n8n version: 1.118.0
  • Database (default: SQLite): Sqlite
  • n8n EXECUTIONS_PROCESS setting (default: own, main): own
  • Running n8n via (Docker, npm, n8n cloud, desktop app): nom
  • Operating system: linux
2

There might be a better way, but I would replace the Upsert with a forked path for the row existing or not and then merge afterward. That way you can reference the existing value if the row is there.