Parse cloudcode beforeSave obtain pre-updated object

Question

In a beforeSave hook I want to obtain the state of the object prior to the update. In this particular case it is to stop a user from changing their choice once

Answer 1

You can use Parse DirtyKeys to identify which field has changed.

   Parse.Cloud.beforeSave(Parse.User, function(request, response) {
  for (dirtyKey in request.object.dirtyKeys()) {
    if (dirtyKey === "yourfieldname") {
      response.error("User is not allowed to modify " + dirtyKey);
      return;
    }
  }
  response.success();
});