Скачать или смотреть Solving the state not updated inside specified function Issue in React Native

Discover how to effectively manage state in functional components within React Native for a seamless user experience.
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This video is based on the question https://stackoverflow.com/q/64802941/ asked by the user 'NewbiewDev' ( https://stackoverflow.com/u/14609908/ ) and on the answer https://stackoverflow.com/a/64803115/ provided by the user 'Mateusz Rostkowski' ( https://stackoverflow.com/u/13138046/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding State Management in React Native

Managing state in React Native, especially within functional components, can sometimes feel daunting. A common issue that developers encounter is updating state in response to user interactions, such as form submissions. Here, we will explore a specific case where the state appears to not update as expected and how to resolve it.

The Problem

Let's consider an example where you have a registration screen in your React Native application. You define an initial state, but when you attempt to update it after a form submission, the state does not reflect the changes correctly.

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What’s Going Wrong?

In the above code snippet:

You are trying to log the current state immediately after calling setState().

The issue arises because state updates in React are asynchronous - they don’t take effect immediately.

This leads to the first part of your confusion: why does state.current_state still print 'initial'?

Additionally, using this.state and this.setState() in a functional component will lead to errors, as these concepts are used in class components rather than functional ones.

The Solution

Instead of relying on immediate state updates after calling setState(), you can utilize the useEffect hook to observe changes to the state. Here’s how you can revise your code:

Step 1: Utilize useEffect

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Step 2: Adding Logic Based on State Change

You can enhance your useEffect to perform actions based on the new state. For instance, you might want to run specific logic when the state transitions to 'login_process'.

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Conclusion

By understanding the asynchronous nature of state updates in React Native, you can better manage state in your applications. Remember to use the useEffect hook to react to changes in state rather than attempting to log or use the updated state immediately after calling setState(). This method not only tidies up your code but ensures that your components respond correctly to state transitions.

With these strategies in hand, you can now manage state in your React Native applications with greater confidence and effectiveness!