I'm trying to work out how to approve an item in O365. From the looks of the current approval examples the item is not approved based on the task being complete. The 'Update List Item' action doesn't allow you to select the 'Approval Status' field. I've also tried using the 'Call HTTP Web Service' action but I'm unable to get this working in a workflow. I've got it working in a separate REST client Application but in the workflow I'm limited in the format that I can put in the 'Request Content' field of the 'Call HTTP Web Service' action.
Does someone know how to approve an item? Or at least perform an item update using the 'Call HTTP Web Service' action?