Better way to access Outlook Calendar without UI in a background application

Question

Scenarios for accessing the Calendar usually involve the user signing in and granting consent to give delegated permissions. This seems to apply to both Office 365 and Graph APIs.

I have seen solutions here for accessing Calendar without UI, but it involves storing the username and password which is less than desired. The other option is using the Graph API with application permission - unfortunately, the Calendars.ReadWrite permission is for all users: "Read and write calendars in all mailboxes". It's unlikely I can get this access granted by an admin as I work in a large company, not to mention I simply don't need that much access.

So my question is, is there any way to get application permission (or any other way to access outlook calendar without UI) for only a handful of users?

Answer 1

You can use scoping https://github.com/microsoftgraph/microsoft-graph-docs/blob/master/concepts/auth-limit-mailbox-access.md which allows application permissions to be limited to a subset of user. What type of application are you actually trying to create ? Something like getSchedule https://docs.microsoft.com/en-us/graph/api/calendar-getschedule?view=graph-rest-1.0&tabs=http can be used by the logged on user to query another users FreeBusy permission and retrieve a limited subset of information about appointments eg Start,End,Subject,location which is often ample for a lot of calendar applications.