SharePoint 2013 Workflow Cannot Append Attendee Field Properly (Registration Calendar)

Question

Trying to figure out how to implement the solution outlined HERE Put quite a few hours into using a secondary registration list that uses the Title as a Lookup to the Calendar Event Title. That's all well and good but for the life of me can't get the work flow to pipe in the registrant to the "Attendees" field. The best I got was it wiped out what was in there and replaced with the "current user". Tried many variations of fashioning a variable out of the existing users in that field and add ;[WorkFlow Context:Initiator] to it but doesn't work. Then started looking at the SPUser code and tried with VS 2012. After much struggle getting VS 2012 to connect to the SharePoint 2013 site it throws a million errors on the deployment. I basically added a visual web part and threw two buttons in there- Register & Unregister. On the Register button I added your code to the Click session but I am sure I am missing something (many errors like 'SPUser' is a type and cannot be used as an expressing, 'user' is not declared, 'SPFieldUserVAlueCollection' is a type and cannot be used as an expression...).

If you can offer any help I'm not a coder so this one is tough for me- Or if there is a way I am missing to add another field to the Calendar list and have it stored as an array perhaps I can accomplish it that way (don't think its possible)

Also tried setting an email workflow to match the "Created By" field on this secondary list where the Title matches the Event name. This would also meet the requirement where the calendar list can trigger a workflow based on "item changed" and send to anyone who resgistered

Answer 1

Well the answer is kind of silly. The only thing I didn't try was creating the attendees field variable using login name, semicolon delimited. That was the ticket. I actually moved towards doing all this right in the calendar list, and used a secondary list to write some info to for things that can't be recorded in an array in calendar.

The biggest issue that remains is being able to (in SharePoint 2013 Ent) hide the Edit Button for users that NEED to have Edit access just to run the workflow to get their name in the attendee field. The workflow is presented as a custom "register" button on the ribbon so I want to show that but not "Edit" Tried some of the things I saw like adding JS to a content editor web part but it seems to just hide all the appts on the page hosting the calendar web part.