How to Send Meeting Invites Using Microsoft Graph API in C#

Integrate Microsoft Graph SDK

• Microsoft Graph API interacts through requests to Microsoft's cloud services. To simplify C# interactions, integrate the Microsoft Graph SDK. Use NuGet to install the SDK in your project.

 

• Open the NuGet Package Manager in your Visual Studio project and search for Microsoft.Graph to install the library.

 

Install-Package Microsoft.Graph

Authenticate with the Graph API

• Before sending requests, authenticate using Azure AD. This involves getting an access token and configuring your application for necessary permissions (like Calendar.ReadWrite).

 

• Use OAuth 2.0 authentication flow to get the access token. This involves registering your application in Azure AD and using client credentials or interactive user sign-in.

 

• Consider implementing an authentication provider using Microsoft's InteractiveBrowserCredential from the Azure.Identity library for simple setups.

 

using Azure.Identity;
using Microsoft.Graph;

var clientSecretCredential = new ClientSecretCredential(
    "<tenant-id>",
    "<client-id>",
    "<client-secret>"
);

GraphServiceClient graphClient = new GraphServiceClient(clientSecretCredential);

Create a Calendar Event

• Construct a new Event object specifying the details like subject, body, start time, end time, attendees, and location.

 

• Ensure to format the timezone and date-time correctly using ISO 8601 as followed by Microsoft Graph API.

 

var @event = new Event
{
    Subject = "Meeting Invitation",
    Body = new ItemBody
    {
        ContentType = BodyType.Html,
        Content = "Please attend this meeting."
    },
    Start = new DateTimeTimeZone
    {
        DateTime = "2023-10-15T14:00:00",
        TimeZone = "Pacific Standard Time"
    },
    End = new DateTimeTimeZone
    {
        DateTime = "2023-10-15T15:00:00",
        TimeZone = "Pacific Standard Time"
    },
    Location = new Location
    {
        DisplayName = "Conference Room"
    },
    Attendees = new List<Attendee>
    {
        new Attendee
        {
            EmailAddress = new EmailAddress
            {
                Address = "user@example.com",
                Name = "User Name"
            },
            Type = AttendeeType.Required
        }
    }
};

Send the Meeting Invite

• Use the GraphServiceClient instance to make a request to create the event in the user's calendar using the events API.

 

• Specify the calendar, typically identified by the user's email or their unique ID.

 

• Handle exceptions and responses to ensure proper feedback and logging.

 

try
{
    await graphClient.Users["<user-object-id>"].Events
        .Request()
        .AddAsync(@event);

    Console.WriteLine("Meeting invite sent successfully.");
}
catch (ServiceException ex)
{
    Console.WriteLine($"Error sending invite: {ex.Message}");
}

Manage Permissions

• Verify that your Azure AD application has all required Graph API permissions. At minimum, Calendars.ReadWrite permission is necessary to create and manage events.

 

• Depending on your application scenario, consider using both delegated and application permissions for broader access rights.

 

• Ensure that users consent to permissions if your app runs in a delegated permission mode.