Shopify Customer Account Extension Prisma Data Fetching Debugging

Understanding Data Fetching Issues in Shopify Customer Account Extensions

This article analyzes a Shopify Community forum discussion regarding data fetching within a Customer Account Extension, specifically using Prisma. The original poster, plutalexandr, encountered a TypeError while attempting to fetch a user's wishlist data. We'll dissect the problem, examine the provided code, and offer solutions based on the community discussion and best practices.

The Problem: "Failed to construct 'Request': Failed to parse URL"

The core issue reported was a TypeError: Failed to construct 'Request': Failed to parse URL from /apps/wishlist/api. This error typically arises when the browser is unable to interpret the provided URL as a valid URL. In the context of a Shopify app running within an extension, this often points to an incorrect relative path or a missing base URL.

Analyzing the Code Snippet

The provided code snippet reveals a React component (FullPageExtension) designed to display a user's wishlist. Let's examine the relevant parts:

async function fetchWishlist() {
  setLoading(true);

  try {
    const token = await shopify.sessionToken.get();

    const res = await fetch('/apps/wishlist/api', {
      headers: {
        Authorization: `Bearer ${token}`,
      },
    });
    const data2 = await res.json();
    setWishlist(data2);

    const productIds = [
      'gid://shopify/Product/7156668629077',
      'gid://shopify/Product/7156669775957',
      'gid://shopify/Product/7156669546581',
      'gid://shopify/Product/7156669775957',
      'gid://shopify/Product/7242516856917',
    ];
    
    const data = await shopify.query(
      `query wishlistProducts($ids: [ID!]!) {
        nodes(ids: $ids) {
          ... on Product {
            id
            title
          onlineStoreUrl
          handle
          priceRange {
            minVariantPrice {
              amount
              currencyCode
            }
          }
          featuredImage {
            url
          }
        }
      }`,
      {
        variables: {
          ids: productIds,
        },
      }
    );

    setLoading(false);
    setWishlist(data.data?.nodes || []);
  } catch (error) {
    setLoading(false);
    console.log(error);
  }
}

The fetchWishlist function attempts to retrieve wishlist data from two sources: first, from /apps/wishlist/api, and second, using the shopify.query function with a GraphQL query to retrieve product details based on product IDs.

Possible Causes and Solutions

Incorrect Relative Path: The most likely cause is that /apps/wishlist/api is not correctly resolving to the full URL of your app's API endpoint. When running in development mode with a tunnel (e.g., ngrok), the app's URL is different from the production URL.
Missing Base URL: The fetch call might be missing the base URL of your Shopify app. You need to ensure that the /apps/wishlist/api path is correctly prefixed with the app's URL.

Actionable Instructions

Here's how to troubleshoot and resolve the URL parsing error:

Verify the App's URL: Ensure that the app's URL is correctly configured in your Shopify Partner dashboard and that the tunnel is active and correctly forwarding traffic.
Use Environment Variables: Store your app's base URL in an environment variable (e.g., process.env.SHOPIFY_APP_URL). This allows you to easily switch between development and production URLs.
Construct the Full URL: In your fetchWishlist function, construct the full URL dynamically using the environment variable:

const appUrl = process.env.SHOPIFY_APP_URL || 'your-default-url'; // Replace 'your-default-url' with a placeholder
const apiUrl = `${appUrl}/apps/wishlist/api`;

const res = await fetch(apiUrl, {
  headers: {
    Authorization: `Bearer ${token}`,
  },
});

Check Tunnel Configuration: If you're using a tunneling service like ngrok, double-check that the tunnel is correctly configured to forward traffic to your local development server.
CORS Issues: While not explicitly mentioned, CORS (Cross-Origin Resource Sharing) issues can sometimes manifest as URL parsing errors. Ensure that your API endpoint is configured to allow requests from your Shopify app's domain.

Additional Considerations

The code also uses shopify.query, which is a recommended approach for fetching data from Shopify's GraphQL API. This method is generally more reliable than directly constructing URLs, especially when dealing with complex data requirements. However, the initial problem was specifically related to the fetch call to /apps/wishlist/api, suggesting that the app might be attempting to fetch data from its own backend in addition to using Shopify's API.

Conclusion

Debugging URL parsing errors in Shopify Customer Account Extensions requires careful attention to URL construction, environment variables, and tunnel configurations. By following the steps outlined above, developers can effectively resolve these issues and ensure that their extensions can reliably fetch data from both Shopify's API and their own backend services.

Troubleshooting Shopify Customer Account Extension Data Fetching with Prisma