Solving the Issue of useQuery Returning the Same Quantity in Array Objects

Discover how to fix the problem of `useQuery` returning identical quantity values for different orders in your ecommerce application using Apollo Client and GraphQL.
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Addressing the useQuery Issue in Apollo Client

If you're encountering a frustrating situation where your useQuery in Apollo Client is consistently returning the same product quantity for multiple orders, you're not alone. This issue typically arises in applications that manage data using a cache, and it can lead to confusion and incorrect data representation in your ecommerce platform. In this post, we’ll delve into the reasons behind this problem and how to implement a solution effectively.

The Problem: Identical Quantity Values

To set the stage, let's consider an example from an ecommerce website that allows users to order grocery products. After adding an apple with a quantity of 4, when the user adds another order with a quantity of 10 for the same product, the expectation is to see distinct quantities for each order. However, due to the way data is fetched and cached, you may find that both orders reflect the initial quantity of 4 — leading to misleading information for your users.

Here's a snippet of the problematic query that demonstrates this behavior:

[[See Video to Reveal this Text or Code Snippet]]

GraphQL Query Overview

Your GraphQL query might look something like this:

[[See Video to Reveal this Text or Code Snippet]]

The query retrieves all orders for a user, displaying product details including the orderedQuantity. However, if you're observing that all orders reflect the quantity of the first order, the caching mechanism is likely at play.

The Solution: Adjusting the Fetch Policy

To resolve this issue, a straightforward yet effective solution is to modify the fetchPolicy in your useQuery. Here’s how:

Change the Fetch Policy

Switching from "cache-and-network" to "no-cache" ensures that Apollo Client directly fetches the data from the server each time the query executes, bypassing the cache entirely.

Change your query setup to:

[[See Video to Reveal this Text or Code Snippet]]

Key Benefits of Using no-cache

Fresh Data: Ensures that the frontend always receives the most up-to-date data from the server.

No Need for Manual Updates: When using no-cache, there is no requirement to manually update the query results after completing a mutation for placing new orders.

Additional Considerations

While adjusting the fetch policy to "no-cache" should effectively solve the immediate issue, here are other considerations to keep in mind:

Mutation Updates: If you are already updating the query results after placing an order, ensure that the updates use the latest data to avoid mixing old cached entries with new values.

Performance: Be mindful that using no-cache may have performance trade-offs, as it increases the frequency of network requests. Evaluate the user experience to ensure efficiency is maintained.

Conclusion

In summary, if you find that your useQuery always returns the same product quantity for multiple orders, adjusting the fetchPolicy to "no-cache" can help mitigate this issue. By ensuring your application has access to fresh data from the server, you can provide a clearer and more accurate representation of orders to your users.

By addressing the cache strategy in Apollo Client, not only does this resolve the issue at hand, but it also enhances the overall reliability of your data-fetching mechanisms. Happy coding!