Скачать или смотреть Why is my redux state not updating after dispatch? Here’s the solution!

Are you struggling with Redux state updates in your React app? Discover why your Redux state is not updating after dispatch and learn the solution step by step!
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This video is based on the question https://stackoverflow.com/q/68016219/ asked by the user 'Luteya Coulston' ( https://stackoverflow.com/u/13769800/ ) and on the answer https://stackoverflow.com/a/68016478/ provided by the user 'Rishav Maskey' ( https://stackoverflow.com/u/9178147/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Why is my Redux State Not Updating After Dispatch? Here’s the Solution!

When working with Redux in a React application, you may encounter a frustrating issue: the state appears to be updated in Redux DevTools but doesn't reflect in your components. This can be puzzling, especially if you're using middleware like redux-thunk for asynchronous actions. In this guide, we'll explore a common scenario that leads to this problem and provide you with a clear and actionable solution.

Understanding the Problem

In the scenario you've described, you're using redux-thunk to dispatch an action that fetches posts from an API. The action seems to work correctly since you can see the data in Redux DevTools after dispatching. However, your component does not re-render with the fetched posts. Let's take a look at your action and reducer to diagnose the issue:

Your Action

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Your Reducer

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Your Component

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What Could Be Going Wrong?

The root cause of the issue lies in how the state is being updated in your reducer. In Redux, it is crucial not to mutate the state directly. When you call state.push(), you are modifying the existing state array, which can lead to unexpected behavior and cause React to not detect any changes in the state for re-rendering.

The Solution: Immutable State Updates

To resolve the issue, you need to update the state immutably. Instead of pushing new posts into the existing state array, create a new array that contains the existing state and the new posts. This can be achieved using the spread operator. Here’s how to update your reducer:

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Why This Works

When you return a new array instead of mutating the existing state, Redux can correctly detect the changes made to the state. This signals React to re-render components that depend on that particular piece of state. As a result, the Home component will receive the updated posts once the action is dispatched successfully.

Conclusion

By ensuring that you create a new array when updating state in your Redux reducers, you can prevent unexpected behaviors in your React components. This not only adheres to Redux best practices but also ensures your application's data flow remains predictable and manageable.

If you're still facing issues after making this change, make sure to double-check other parts of your Redux setup, such as connecting the reducer properly in your store. Happy coding!