Manipulate csv contents

[stuioco]

Added 3 templating functions to manipulate csv content.

• csvCountRows - returns the number of rows in the data source
• csvDeleteRows - deletes rows with a matching provided field value
• csvAddRow - adds a new row from a provided array

Docs are also updated

[stuioco]

Hi Tommy, the main reason to extend the csv capability from read only to read/write is that it gives a much simpler and more natural mechanism to simulate structured data persistence between calls than having to use journal indexing which can be confusing for complex processes.

[kapishmalik]

It is quite unconventional to do so. We can make another api call to add or delete the data instead of displaying it using template function.

[stuioco]

I agree it's unconventional, but not necessarily a bad idea. I'm struggling to see how using just api calls we can implement a sandbox environment that needs to simulate a mutable persistent back-end that supports CRUD operations on known data structures.

[kapishmalik]

Can't we write middleware to update CSV and it shows that data instead of templating function. Can you help us understand your use case?