Скачать или смотреть Mastering Apollo Client Reactive Variables: A Simple Guide to Triggering Re-renders

Discover how to use `Apollo Client` reactive variables effectively to ensure your components re-render when data updates. This blog demystifies common issues and provides easy solutions.
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Mastering Apollo Client Reactive Variables: A Simple Guide to Triggering Re-renders

When working with Apollo Client in your React application, you may encounter an issue where updating reactive variables does not trigger a re-render of your components. This can be perplexing, especially when you expect your user interface (UI) to reflect the most recent state. In this guide, we will explore how to effectively use reactive variables in Apollo Client and ensure your components re-render as expected.

Understanding the Problem

Here's a typical scenario:

You have a reactive variable (colorVar) defined in a cache file.

You update the value of this variable in one file (File A).

You read the value from this variable in another file (File B), expecting the UI to update.

However, the re-render of File B does not happen after the variable is updated in File A.

This raises the question: How can we ensure that changes in our reactive variables trigger a re-render of dependent components?

The Solution: Setting Up Apollo Client Properly

To resolve this issue, we need to correctly set up the Apollo Client's cache and utilize appropriate methods to trigger re-renders on updates.

Step 1: Setting Up Your Cache File

In your cache file, you'll want to make sure that the reactive variable and its fields are defined correctly. Here's how you can do that:

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

Step 2: Updating the Variable in File A

Whenever you need to update the color variable (for example, setting it to green), you can do so in File A like this:

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

Step 3: Reading the Variable in File B

Next, you need to set up File B to correctly read the value of the color variable. You can achieve this using the useQuery hook with a GraphQL query that accesses your reactive variable.

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

Update: Using the useReactiveVar Hook

From Apollo Client version 3.2.0 onwards, you have the option to use the useReactiveVar hook, which simplifies reading and updating reactive variables. Here's how you can use it in File B:

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

Conclusion

By following the above steps, you can ensure that your reactive variables are correctly set up to trigger re-renders across your components. Utilizing Apollo Client's cache effectively and leveraging reactive variables can enhance the responsiveness of your application, improving user experience.

In summary, always remember to:

Define reactive variables in the Apollo Client's cache configuration.

Use queries or the useReactiveVar hook to access those variables in your components.

Ensure that your components are subscribed to the necessary updates in their state.

With these practices, you can take full advantage of the reactive programming model that Apollo Client provides.

Feel free to reach out if you have any questions or need further clarification on using Apollo Client!