View previous version data from SharePoint List Item

[hitty08]

Currently I have a people picker column within a SP list. The Column name is 'AssignedTo' and allows for multiple users to be selected. When the initial users are assigned, they are notified of being assigned via a separate flow. It was recently brought to my attention that additional users will start to be assigned after the fact. When additional people are assigned to that column I would like to send an e-mail out (just to the newly assigned people) notifying them that they have been assigned, but not notifying the previously assigned users. I have successfully compared the current version of the list to a previous version (19 to 18) but is it possible to see what 18 was originally? 

What I have done so far is 

1.  When an item is created or modified
2. Get changes for an item or file (properties only)
   1. Chose Site
   2. Choose List
   3. ID = (Dynamic Content) ID 
   4. Since = (Expression) sub(int(triggerOutputs()?['body/{VersionNumber}']),1)
3. Then I run a control to target the AssignedTo Column looking to see if its boolean value has changed 

No matter what I try though, I am always pulling in both the old users and the new ones. I am assuming I need to put version 18 into its own array and then version 19 into its own array, but I am having no luck on how to target just the version 18 data. Any help would be greatly appreciated. 

[shoog]

You can retrieve the previous version of an item using the "Send an HTTP request to SharePoint" action.

Make sure the method is set to GET and send an Accept header with value application/json

The url would be

/_api/web/lists/getByTitle('your list name')/items(yourItemID)/Versions?$filter=IsCurrentVersion eq false&$orderby=versionId desc&$top=1

replace 'your list name' with the list you are using and yourItemID with the item ID.