How to Use Microsoft Graph API to Access Planner Tasks in C#

Introduction to Microsoft Graph API

• Microsoft Graph API is a gateway to access data and intelligence from Microsoft 365. It provides a unified programmability model that you can use to access the tremendous amount of data in Microsoft 365, including the Planner tasks.

Create a Microsoft Graph Application

• You will need a registered application in Azure Active Directory (AAD). Make sure your application has the necessary permissions to access Planner tasks. Required permissions usually include `Tasks.ReadWrite` or similar, depending on the level of access your application needs.

Obtain Authorization

• For accessing Microsoft Graph API in C#, you need to implement OAuth 2.0 authentication to get an access token. You will be using either the `Authorization Code Grant` or the `Client Credentials Grant` depending on whether you are accessing the data on behalf of a user or on behalf of an application.
• Use the MSAL (Microsoft Authentication Library) for this purpose, which simplifies the process.
• Here is a basic snippet to acquire a token using the client credentials flow:

var app = ConfidentialClientApplicationBuilder.Create(clientId)
    .WithClientSecret(clientSecret)
    .WithAuthority(new Uri(authority))
    .Build();

var scopes = new[] { "https://graph.microsoft.com/.default" };

AuthenticationResult result = await app.AcquireTokenForClient(scopes).ExecuteAsync();

string accessToken = result.AccessToken;

Install Microsoft Graph SDK

• To facilitate the communication with Microsoft Graph, install the Graph SDK in your project. It provides fluent models and helpers that make API interactions simple and intuitive.
• Use the Package Manager Console to install the Microsoft Graph SDK:

Install-Package Microsoft.Graph

Setup the Graph Service Client

• Initialize the GraphServiceClient with your access token. The GraphServiceClient is the main class you will use to make requests to Microsoft Graph.

GraphServiceClient graphClient = new GraphServiceClient(
    new DelegateAuthenticationProvider((requestMessage) =>
    {
        requestMessage.Headers.Authorization =
            new AuthenticationHeaderValue("bearer", accessToken);

        return Task.CompletedTask;
    }));

Access Plans and Tasks

• Retrieve the list of plans to which a user has access using `graphClient`. Plans are part of the Planner, and each plan can contain several tasks.
• For accessing tasks under a specific plan, you need the plan's ID. Retrieve tasks using the plan ID, as shown below:

// Retrieve planner plans
var plans = await graphClient.Me.Planner.Plans.Request().GetAsync();

foreach (var plan in plans)
{
    Console.WriteLine($"Plan: {plan.Title}");
    
    // Retrieve tasks for a specific planner plan
    var tasks = await graphClient.Planner.Plans[plan.Id].Tasks.Request().GetAsync();
    
    foreach (var task in tasks)
    {
        Console.WriteLine($"Task: {task.Title} - Due: {task.DueDateTime}");
    }
}

Handling Errors and Pagination

• Since Planner may return numerous tasks or plans, Microsoft Graph API handles pagination. Always check for additional pages of results using the `NextPageRequest` property.
• Handle exceptions such as authentication failures, network errors, etc., using try-catch blocks around your asynchronous API requests.

try
{
    var tasks = await graphClient.Me.Planner.Tasks.Request().GetAsync();
    
    if (tasks.NextPageRequest != null)
    {
        // Fetch additional pages
        var moreTasks = await tasks.NextPageRequest.GetAsync();
    }
}
catch (ServiceException ex)
{
    Console.WriteLine($"Error: {ex.Message}");
}

Conclusion

• Using the Microsoft Graph API with C# allows for detailed interaction with Microsoft Planner data, offering the ability to integrate and automate operations within the Microsoft 365 ecosystem.
• By leveraging the Microsoft Graph SDK, the complexity of making API calls is greatly reduced, facilitating rapid development of functionality.