Proof of Concept

This proof of concept demonstrates how to store an Excel file to Onedrive/Sharepoint and open the file with Excel Online using Dotnet Framework 4.61.

Microsoft Graph Api

This application use the Microsoft Graph API to store files in a Sharepoint Site. Documentation for the Microsoft Graph SDK.

Authentication

The web application authenticates to Microsoft using a Service Principal.

Create a Service Principal

To create a service princial go to the Azure Portal and sign in as a Global Administrator

1. Go to Microsoft Entra Id
2. Click Enterprise Applications
3. Click New application
4. Click Create your own application
5. Give the aplication a name and select Register an application to integrate with Microsoft Entra ID (App you're developing), click Next
6. Select Accounts in this organizational directory only (Your tenanat name only - Single tenant) and click Register

Grant Graph API permissions to the Service Principal

1. Search for your application in Entra Id | App Registrations
2. Select Api Permissions and click Add a permission
3. Select Microsoft Graph
4. Select Application Permission
5. Type Files in the serachbar and select Files.ReadWrite.All and click Add Permission
6. Click Grant admin consent for Your tenanat name

Create a Client Secret for your service principal

1. Search for your application in Entra Id | App Registrations
2. Select Certificates & secrets and click New Client Secret
3. Give your secret a name and expire date and click Add

Important

Copy and store the client secret value in a secure location. This is the only time you are allowed to do this

Configure the application to use the service principal

The application use the Azure.Identity nuget package, and the code expects the following environment variables

Variable name	Value
AZURE_CLIENT_ID	ID of a Microsoft Entra application
AZURE_CLIENT_SECRET	The application's client secrets
AZURE_TENANT_ID	ID of the application's Microsoft Entra tenant