Build Go apps with Microsoft Graph

This tutorial teaches you how to build a Go console app that uses the Microsoft Graph API to access data on behalf of a user.

In this tutorial, you will:

• Get the signed-in user
• List the user's inbox messages
• Send an email

Prerequisites

Before you start this tutorial, you should have Go installed on your development machine.

You should also have a Microsoft work or school account with an Exchange Online mailbox. If you don't have a Microsoft 365 tenant, you might qualify for one through the Microsoft 365 Developer Program; for details, see the FAQ. Alternatively, you can sign up for a one-month free trial or purchase a Microsoft 365 plan.

Register an application for user authentication

Register an application that supports user authentication using device code flow. You can register an application using the Microsoft Entra admin center, or by using the Microsoft Graph PowerShell SDK.

Create a Go console app

Begin by initializing a new Go module using the Go CLI. Open your command-line interface (CLI) in a directory where you want to create the project. Run the following command.

go mod init graphtutorial

Install dependencies

Before moving on, add dependencies that you use later.

• Azure Identity Client Module for Go to authenticate the user and acquire access tokens.
• Microsoft Graph SDK for Go to make calls to the Microsoft Graph.
• GoDotEnv for reading environment variables from .env files.

To install the dependencies, run the following commands in your CLI.

go get github.com/Azure/azure-sdk-for-go/sdk/azidentity
go get github.com/microsoftgraph/msgraph-sdk-go
go get github.com/joho/godotenv

Load application settings

Next, add the details of your app registration to the project.

1. Create a file in the same directory as go.mod named .env and add the following code.

   CLIENT_ID=YOUR_CLIENT_ID_HERE
   TENANT_ID=common
   GRAPH_USER_SCOPES=user.read,mail.read,mail.send
   

2. Update the values according to the following table.

   Setting	Value
   CLIENT_ID	The client ID of your app registration
   TENANT_ID	If you chose the option to only allow users in your organization to sign in, change this value to your tenant ID. Otherwise leave as common.

   Tip

   Optionally, you can set these values in a separate file named .env.local.

Design the app

Continue by creating a simple console-based menu.

1. Create a new directory in the same directory as go.mod named graphhelper.

2. Add a new file in the graphhelper directory named graphhelper.go and add the following code.

   package graphhelper
   
   import (
       "context"
       "fmt"
       "os"
       "strings"
   
       "github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
       "github.com/Azure/azure-sdk-for-go/sdk/azidentity"
       auth "github.com/microsoft/kiota-authentication-azure-go"
       msgraphsdk "github.com/microsoftgraph/msgraph-sdk-go"
       "github.com/microsoftgraph/msgraph-sdk-go/models"
       "github.com/microsoftgraph/msgraph-sdk-go/users"
   )
   
   type GraphHelper struct {
       deviceCodeCredential *azidentity.DeviceCodeCredential
       userClient           *msgraphsdk.GraphServiceClient
       graphUserScopes      []string
   }
   
   func NewGraphHelper() *GraphHelper {
       g := &GraphHelper{}
       return g
   }
   

   This code creates a basic GraphHelper type that you extend in later sections to use Microsoft Graph.

3. Create a file in the same directory as go.mod named graphtutorial.go. Add the following code.

   package main
   
   import (
       "fmt"
       "graphtutorial/graphhelper"
       "log"
       "time"
   
       "github.com/joho/godotenv"
   )
   
   func main() {
       fmt.Println("Go Graph Tutorial")
       fmt.Println()
   
       // Load .env files
       // .env.local takes precedence (if present)
       godotenv.Load(".env.local")
       err := godotenv.Load()
       if err != nil {
           log.Fatal("Error loading .env")
       }
   
       graphHelper := graphhelper.NewGraphHelper()
   
       initializeGraph(graphHelper)
   
       greetUser(graphHelper)
   
       var choice int64 = -1
   
       for {
           fmt.Println("Please choose one of the following options:")
           fmt.Println("0. Exit")
           fmt.Println("1. Display access token")
           fmt.Println("2. List my inbox")
           fmt.Println("3. Send mail")
           fmt.Println("4. Make a Graph call")
   
           _, err = fmt.Scanf("%d", &choice)
           if err != nil {
               choice = -1
           }
   
           switch choice {
           case 0:
               // Exit the program
               fmt.Println("Goodbye...")
           case 1:
               // Display access token
               displayAccessToken(graphHelper)
           case 2:
               // List emails from user's inbox
               listInbox(graphHelper)
           case 3:
               // Send an email message
               sendMail(graphHelper)
           case 4:
               // Run any Graph code
               makeGraphCall(graphHelper)
           default:
               fmt.Println("Invalid choice! Please try again.")
           }
   
           if choice == 0 {
               break
           }
       }
   }
   

4. Add the following placeholder methods at the end of the file. You implement them in later steps.

   func initializeGraph(graphHelper *graphhelper.GraphHelper) {
       // TODO
   }
   
   func greetUser(graphHelper *graphhelper.GraphHelper) {
       // TODO
   }
   
   func displayAccessToken(graphHelper *graphhelper.GraphHelper) {
       // TODO
   }
   
   func listInbox(graphHelper *graphhelper.GraphHelper) {
       // TODO
   }
   
   func sendMail(graphHelper *graphhelper.GraphHelper) {
       // TODO
   }
   
   func makeGraphCall(graphHelper *graphhelper.GraphHelper) {
       // TODO
   }
   

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

Next step