Shopify App OAuth 

Shopify apps that will be installed on multiple shops must implement Shopfiy's OAuth process to get installed. Gadget provides a well-tested implementation of Shopify's OAuth out of the box for each Gadget app.

Gadget's Shopify OAuth implementation 

Gadget implements Shopify OAuth on behalf of each Gadget application. To complete the OAuth process, your application needs to redirect merchant visits into Gadget's OAuth flow, and then handle the final request once the flow is complete.

Here's the OAuth process in detail:

1. The OAuth process is initiated by the merchant when they install the app from the Shopify App Store or a given install link.
2. The merchant is redirected to the App URL as set in the Shopify Partners dashboard for your application. If the merchant hasn't installed the app before, the app is responsible for initiating the OAuth process to install the application. Gadget provides a default App URL of /api/shopify/install-or-render which will do this automatically.
3. The app initiates installation by redirecting the merchant to Gadget's OAuth kickoff endpoint. Gadget's generated frontend UI detects uninstalled merchants and does this automatically.
4. Gadget's OAuth implementation redirects the merchant to Shopify's OAuth consent screen.
5. The merchant views the app's requested permissions.
6. The merchant confirms consent for these scopes, and clicks the Install button.
7. Shopify marks the app as installed, and redirects the merchant to the OAuth Callback URL as set in the Shopify Partners dashboard for your application. If configured correctly, this will send the merchant back to Gadget's platform OAuth implementation at /api/connections/shopify/auth/callback.
8. Gadget's platform OAuth implementation runs the install action on the shopifyShop model, recording the given access_token from Shopify and running any custom action code you've added to your app.
9. Gadget's platform OAuth implementation redirects the merchant to your app embedded within the Shopify Admin.
10. The merchant views the app's UI in the embedded iframe, rendering the frontend React application from your app's frontend folder.

Configuration values 

Gadget provides a value for both the App URL and the OAuth Callback URL for saving in the Partners dashboard. Gadget recommends using the defaults provided when creating your application:

Find the values for your application in the Shopify section of your application's Shopify Connection page in the Gadget editor.

In the past, Gadget recommended that Shopify applications utilize the /shopify/install URL as the configuration value for their App URL setting within Shopify. This URL served as the entry point where Shopify directed both newly uninstalled merchants looking to install an app and existing merchants seeking to use the application. The performance of this particular route was critical, as it represented the initial interaction each merchant had with your application.

Now, Gadget introduces a high-performance entry point tailored for Shopify applications, designed to enhance the Largest Contentful Paint (LCP) time of your app. This new route will initiate the OAuth and installation process for new merchants, while seamlessly redirecting existing merchants to the / route to render the frontend experience of your application. Gadget has optimized this route to deliver the fastest possible performance, and it doesn't require activating the serverless runtime for your application, ensuring consistently low latency.

For new applications, Gadget will automatically use this URL as the default setting. However, for existing applications, you can leverage this improved route by updating your App URL to <your-app-domain>/api/shopify/install-or-render.

Customization 

If you'd like to change the behavior of your application's OAuth implementation, you can take over the App URL by adding a custom route to your application. For example, you can add a custom route at routes/shopify/GET-install.js

Here's an example route that implements the same behavior as Gadget's default that you can customize:

routes/shopify/GET-install.js
JavaScript
Copy
1import { RouteContext } from "gadget-server";
2
3/**
4 * Route handler for GET install
5 *
6 * @param { RouteContext<{ Querystring: { hmac: string; shop: string; apiKey: string; host: string; embedded?: "1" } }> } route context - see: https://docs.gadget.dev/guides/http-routes/route-configuration#route-context
7 *
8 */
9export default async function route({ request, reply, api, logger, connections }) {
10  const { query, gadgetContext } = request;
11  const { hmac, shop: shopDomain, embedded, host: base64Host } = query;
12  const { apiKey } = gadgetContext;
13
14  if (!hmac || !shopDomain) {
15    // Before rendering this route, Gadget will automatically verify the hmac on your behalf when both of these parameters are present
16    // If either is missing, then this is not a request initiated by Shopify so we'll redirect to the root page
17    return await reply.redirect("/");
18  }
19
20  // if you have two or more apps configured for the same environment, it's possible that you could install the same shop twice on the same environment
21  // if we don't find one with this api key, going through the OAuth flow will update any existing shop record with the new api key from this app
22  const shop = (
23    await api.shopifyShop.findMany({
24      filter: {
25        myshopifyDomain: { equals: shopDomain },
26        installedViaApiKey: { equals: apiKey },
27        state: { inState: "created.installed" },
28      },
29    })
30  )[0];
31
32  // An array of all the Shopify scopes that your Gadget app requires
33  const requiredScopes = Array.from(
34    connections.shopify.configuration.requiredScopes
35  );
36
37  // This is the single entry point to your app from Shopify. It is both the route that is hit on the initial app install
38  // as well as every time a merchant clicks on your app in their admin
39  if (shop) {
40    const hasAllRequiredScopes = requiredScopes.every((requiredScope) =>
41      shop.grantedScopes?.includes(requiredScope)
42    );
43    if (embedded) {
44      return await reply.redirect("/?" + new URLSearchParams(query).toString());
45    } else {
46      const host = Buffer.from(base64Host, "base64").toString("ascii");
47      return await reply.redirect(`https://${host}/apps/${apiKey}`);
48    }
49  } else {
50    // If there's no shop record, this is a fresh install, proceed through OAuth with Shopify
51    logger.info({ shop }, "New app installation, redirecting through OAuth flow");
52  }
53
54  // This route will kick-off an OAuth flow with Shopify, pass along all parameters from Shopify (hmac, host, shop, etc)
55  const redirectURL =
56    "/api/connections/auth/shopify?" + new URLSearchParams(query).toString();
57
58  // Redirect the merchant through the OAuth flow to grant all required scopes to your Gadget app.
59  // At the end of this flow, the App URL in the connection configuration will point back to this route
60  await reply.redirect(redirectURL.toString());
61}