Export calendar Items to a CSV file using Microsoft Graph and Powershell

For the last couple of years the most constantly popular post by number of views on this blog has been Export calendar Items to a CSV file using EWS and Powershell closely followed by the contact exports scripts. It goes to show this is just a perennial issue that exists around Mail servers, I think the first VBS script I wrote to do this type of thing was late 90's against Exchange 5.5 using cdo 1.2.

Now it's 2020 and if your running Office365 you should really be using the Microsoft Graph API to do this. So what I've done is create a PowerShell Module (and I made it a one file script for those that are more comfortable with that format) that's a port of the EWS script above that is so popular. This script uses the ADAL library for Modern Authentication (which if you grab the library from the PowerShell gallery will come down with the module). Most EWS properties map one to one with the Graph and the Graph actually provides better information on recurrences then EWS did. Where extended properties where used in the EWS script the equivalent is used in the Graph. (The only real difference is the AppointmentState property which is a strongly typed property in EWS but I had to use the Extended property in the Graph).

Just a couple of things if your new to Microsoft Graph scripts and Modern Authentication that you need to know

1. You need an Approved Azure Application registration to use this (or any script that is going to access the Graph). The Microsoft walk-throughs https://docs.microsoft.com/en-us/graph/auth-register-app-v2 are pretty good at describing how to do this. Specific config I recommend you use

"https://login.microsoftonline.com/common/oauth2/nativeclient" as the redirectURL (this is part of the Suggested Redirect URIs for public clients (mobile, desktop)).

2. Permission for the above

You only need the following permissions for this script to work, Calendar.Read gives you rights to the calendar the account that is being used and Calendar.Read.Shared gives you read access to any calendars that the account being used has been granted access to (eg via delegation, admin portal or add-mailboxpermission). 

Then you just need to copy the Application (client) ID guid from the overview screen in the Applicaiton Registration  and use that as in the -clientId paraemter in the Export-GCECalendarToCSV cmdlet.

I've included a demo multi tenant app registration as the default in the module that just has these rights which you can use for testing but I would always recommend you create you own.

You can install the module which will give you access to the Export-GCECalendarToCSV and Export-GCECalendar cmdlets from the Powershell gallery https://www.powershellgallery.com/packages/MSGraph-ExportCalendar/  (see the instruction on that page).

Or if you want to take the script and modify it yourself its located on GitHub https://github.com/gscales/Powershell-Scripts/blob/master/MSGraph-ExportCalendar/functions/Export-GCECalendarToCSV.ps1

Simple example of exporting the last 7 days of calendar appointment to csv

Export-GCECalendarToCSV -MailboxName gscales@datarumble.com -StartTime (Get-Date).AddDays(-7) -EndTime (Get-Date) -FileName c:\temp\Last7.csv

Using Azure device code authentication on a arduino iot 33 and getting the Teams presence from the Microsoft Graph

A while ago I published this post on accessing the Graph directly from an Arduino, this made use of the "resource owner password credentials grant" (meaning it used a hard coded username and password). Once you have enabled MFA (multi factor authentication) on an account this grant no longer works because you have no ability to provide the other factors for the Authentication to succeed.  For devices like Arduino's or most IOT devices that have very limited UI capabilities this is where device code authentication can be used.

The way Device Code Authentication works is instead of posting the user credentials to the token endpoint to get an access token, you make a post first to the /v2.0/devicecode endpoint which will then give you a specific user code to use to authenticate with on another device. You then visit http://microsoft.com/devicelogin (on a pc or mobile device) enter the user code and authenticate as the required user doing any extra MFA authentication. In the meantime the limited UI device polls the Token Endpoint and once authentication has been completed(on the external device) instead of the endpoint returning a pending error the poll results will be a normal Access token (and refresh token) that can then be used to access any Graph resources you have access to.

Visually on the Serial port here is what the whole process looks like on the Arduino

The last part of this code makes a request to get the Presence from Microsoft Teams which was introduced into beta in the Microsoft Graph in December see https://docs.microsoft.com/en-us/graph/api/resources/presence?view=graph-rest-beta.

So putting this all together you can make a simple Teams presence light with a circuit like (circuit is for demonstration purposes only)

and processing the Presence result you can get returned from the Graph using the code I've referenced below

A few notes on Device code Authentication, its important when you setup your App Registration in the Azure Portal that you mark your registration as public "Treat application as a public client" eg

Device code requests must be made against the Tenant endpoint (so you can't use the common endpoint). In the code I've included discovery code that gets the tenant specific endpoint to use based on the domain name stored in the Secrets file.

Also if your reading this because your following the documentation for Device code on https://docs.microsoft.com/en-us/azure/active-directory/develop/v2-oauth2-device-code and you can't get it to work there is an issue with the payload information in the document. Where device_code is used as a parameter name in the payload in the documentation it should just be code with your device code as the value.

I've put the sketch which contains the code I've used for Device Code authentication and grabbing the presence from the Microsoft Graph on GitHub here https://github.com/gscales/MS-Graph-Arduino/tree/master/MSGraph-Presence please refer to my previous article on details on getting you code up and running on an Arduino Iot33 which include downloading the SSL certs to the device which is required (also flash the firmware).

A couple of notes on the code because the Json parsing library I used can't handle the access token response I needed to manually parse the token out (which is a little frustrating) but is one of the chanllendges of working with Arduino's and dealing with the issues that limited memory causes.