Hi Alex,
I've checked your link and see following mistakes:
1 In your "read" service you don't pass "_id" for current item to get.
See details: http://prntscr.com/42sm9r/direct
2 In your "query" service you don't correctly pass "where" request parameter.
See details: http://prntscr.com/42sn9l/direct
In "where" you should add JS code:
pre
//In this object you need set correct search criteria.
var whereObject = {role: "Instructor"};
return JSON.stringify(whereObject);
/pre
On "success" event for "query_instructor" datasource you have JS code where you "create" or "list" instructors.
If i've understand you corretly you need to "create" or "update" service. So please check it out.
Regards.