02-create-app.md

Create a .NET Core console app

Begin by creating a new .NET Core console project using the .NET Core CLI.

1. Open your command-line interface (CLI) in a directory where you want to create the project. Run the following command.

   dotnet new console -o GraphGettingStarted

2. Once the project is created, verify that it works by changing the current directory to the GraphGettingStarted directory and running the following command in your CLI.

   cd GraphGettingStarted
   dotnet run

   If it works, the app should output Hello World!.

Install dependencies

Before moving on, add some additional dependencies that you will use later.

• Microsoft.Extensions.Configuration.UserSecrets to read application configuration from the .NET development secret store.
• Azure SDK Client Library for Azure Identity to authenticate the user and acquire access tokens.
• Microsoft Graph .NET Client Library to make calls to the Microsoft Graph.

Run the following commands in your CLI to install the dependencies.

dotnet add package Microsoft.Extensions.Configuration.UserSecrets --version 5.0.0
dotnet add package Azure.Identity --version 1.4.1
dotnet add package Microsoft.Graph --version 4.16.0

Design the app

In this section you will create a simple console-based menu.

Open Program.cs in a text editor (such as Visual Studio Code) and replace its entire contents with the following code.

Console.WriteLine(".NET Core Graph Tutorial\n");

int choice = -1;

while (choice != 0) {
    Console.WriteLine("Please choose one of the following options:");
    Console.WriteLine("0. Exit");
    Console.WriteLine("1. Display access token");
    Console.WriteLine("2. View the signed in user");
    Console.WriteLine("3. View the signed in user emails");
    Console.WriteLine("4. Send an email as the signed in user");

    try
    {
        choice = int.Parse(Console.ReadLine()!);
    }
    catch (System.FormatException)
    {
        // Set to invalid value
        choice = -1;
    }

    switch(choice)
    {
        case 0:
            // Exit the program
            Console.WriteLine("Goodbye...");
            break;
        case 1:
            // Display access token
            break;
        case 2:
            // Get signed in user
            break;
        case 3:
            // Get messages
            break;
        case 4:
            // Send mail
            break;
        default:
            Console.WriteLine("Invalid choice! Please try again.");
            break;
    }
}

This implements a basic menu and reads the user's choice from the command line.

Next step