How to Create a Shopify App with .NET and C#: A Step-by-Step Guide

Step 4: Create Your Shopify App's Authentication Flow

Now that you have your OAuth credentials, you can create your app's authentication flow. This flow will allow your app to authenticate with Shopify and access its APIs. Follow these steps:

1. Create a new ASP.NET MVC controller called "AuthController".
2. Add the following code to the controller:



public class AuthController : Controller
{
private readonly string _apiKey = "YOUR_API_KEY";
private readonly string _apiSecret = "YOUR_API_SECRET";
public ActionResult Index()
{
    string redirectUrl = $"https://{Request.Url.Host}/auth/callback";
    string authUrl = $"https://{_apiKey}:{_apiSecret}@{Request.QueryString["shop"]}.myshopify.com/admin/oauth/authorize?client_id={_apiKey}&scope=read_products,write_products&redirect_uri={redirectUrl}";
    return Redirect(authUrl);
}
public ActionResult Callback(string shop, string code)
{
    string accessTokenUrl = $"https://{_apiKey}:{_apiSecret}@{shop}.myshopify.com/admin/oauth/access_token";
    var values = new NameValueCollection
    {
        { "client_id", _apiKey },
        { "client_secret", _apiSecret },
        { "code", code }
    };
    using (var client = new WebClient())
    {
        var response = client.UploadValues(accessTokenUrl, values);
        var responseString = Encoding.Default.GetString(response);
        var qs = HttpUtility.ParseQueryString(responseString);
        string accessToken = qs["access_token"];
        // Save the access token to a cookie or database for future use
        return RedirectToAction("Index", "Home");
    }

This code defines two actions:

• The Index action handles the initial authentication request. It redirects the user to the Shopify authorization page, passing along your app's client ID, scopes, and redirect URL.
• The Callback action handles the callback from Shopify. It exchanges the authorization code for an access token, which you can use to make authenticated API requests to Shopify. In this example, the access token is saved to a cookie or database for future use.

Note that in the code above, you'll need to replace the placeholders for your app's API key and secret.

Step 5: Make Authenticated Requests to the Shopify API

Now that you have an access token, you can make authenticated requests to the Shopify API using the Shopify .NET SDK. Here's an example:

var service = new ProductService("YOUR_SHOPIFY_DOMAIN", "YOUR_ACCESS_TOKEN");var product = new Product
{
Title = "My new product",
BodyHtml = "This is the description of my new product.",
Vendor = "MyVendor",
ProductType = "MyProductType",
Published = true,
Variants = new List
{
new ProductVariant
{
Price = "19.99",
Option1 = "Default",
Sku = "MY_PRODUCT_SKU"
}
}
};
product = service.Create(product).Result;

This code creates a new product in Shopify using the authenticated API client. Note that in the code above, you'll need to replace the placeholders for your Shopify domain and access token.

Conclusion

In this tutorial, we've covered the basics of creating a Shopify app with .NET and C#. By following these steps, you should now have a working app that can authenticate with Shopify and make authenticated API requests. From here, you can build out your app's functionality and add more features to create a robust Shopify app.

If you're new to .NET or C#, don't worry! There are plenty of resources available online to help you get started, including documentation and tutorials. And if you get stuck, don't hesitate to reach out to the Shopify developer community for help.

Happy coding!