Call all child records through API

Hi. I want to call all the Sales Invoice Items to connect to PowerBI. Using the /api/resource/Sales%20Invoice%20Item I get a Not Permitted message. I do not want to pass Invoice by Invoice to get the data, I want to connect directly to this doctype. How can I give such permission?
Any help is appreciated.

Hi Pablo, I’m having the same issue, did you find any way to do it?

I don’t think this is possible via the REST API, by design. It should be possible to do with a whitelisted method or a server script, however.