I'm using Microsoft Flow to add records to a feature service using the HTTP action. I want to also use Flow to add a PDF attachment to the newly created feature. I'm creating the PDF in the same Flow, so I can use the File content in a later step. I can get the feature's objectID and pass this into the URI, but I can't work out how to add the PDF to the body of the request. I've tried composing it as Base64 and this doesn't work either.
Please can someone help?