How to add the new value to the existing value using Airtable automation

[RSk]

Hi, My Airtable use case is to maintain Farmer’s finances. We have developed a WhatsApp bot, and by using webhook triggers the information gets stored in Airtable.

I am using webhooks to populate the Expense Amount field. For eg: The bot asks the question about the Expense Amount, as soon as the user answers this question, the webhook triggers, and the value of the Expense Amount gets updated.

What I am trying to achieve is, if the User enters the Expense Amount for the same expense type, the field should add/sum the new value to the previously populated value.

For eg: If the user John, enters the Expense Amount for E1 as 200 again then the Expense Amount field should be 300(100 + 200).
I want to append the new incoming values in the field and not overwrite it. 

Any advice or help is appreciated

[kuovonne]

Can you provide more details on what your webhook currently does? Does it create a new record, or does it find the existing record and overwrite the values? What platform are you using to make these data changes?

I also recommend considering a new linked table where all transactions with the same user and expense type are linked to the same record, and then use a rollup field to sum the values. This will preserve the individual record data and also provide you with the sum.

[RSk]

I have edited the question.

1. The webhook updates the Expense Amount field. 

2. WhatsApp is our source of information, all the information gets stored/ updated based on the bot flow.

Can you please guide me to some articles or similar implementations for reference?