How to Properly Manage useState with Data Fetching in React Native

Learn how to correctly order data-fetching and `useState` in React Native to avoid common pitfalls when working with asynchronous data.
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How to Properly Manage useState with Data Fetching in React Native

As a newcomer to React Native, encountering issues while managing state, especially when it relates to data fetching, can be quite common. If you're using Apollo Client for fetching data with GraphQL, you may face a specific problem: the warning about rendering more hooks than during the previous render. This is usually due to the placement of useState hooks relative to conditional rendering in your component. In this guide, we will explore the issue and its solution in a clear and concise manner.

Understanding the Problem

In the initial code snippet provided, the user is attempting to manage states for a search query and filtered items alongside a data fetching operation. The setup is as follows:

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

The error message:

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

indicates that the number of hooks being rendered varies depending on the conditional checks. This is bad practice because hooks are expected to be called in the same order during every render cycle.

The Solution

To solve this issue, we'll need to restructure how we handle state management in relation to the asynchronous data fetching. The solution involves utilizing the useEffect hook, which allows us to run side effects in functional components.

Step-by-Step Breakdown

Initialize State Outside Conditional Statements:
Move the initialization of useState for displayed before any conditional statement. You can initialize it to an empty string or an empty array depending on your needs.

Use useEffect to Update State:
Use the useEffect hook to update the displayed state whenever the data you fetched changes. This way, you ensure that your component will re-render with the new data once fetched.

Here's how it can be implemented:

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

Key Points to Remember

Placement of Hooks: Always place your state and effect hooks at the top level of your functional components. This ensures they are called in the same order on each render.

Initial State: It's perfectly fine to initialize your state based on an empty value first and then update it later in the effect.

Asynchronous Data Handling: Learn to embrace the asynchronous nature of data fetching, using hooks like useEffect to manage side effects effectively.

By following these principles, you'll not only fix the rendering issue but also improve your overall understanding of state management in React Native applications.

Conclusion

Managing data fetching and state with hooks in React Native can seem daunting at first, especially with asynchronous code. However, by restructuring your code and effectively using useEffect, you can prevent common pitfalls and build robust applications. Embrace these patterns, and soon, you'll have your React Native components handling data like a pro. Happy coding!