Скачать или смотреть Solving Unhandled Rejection (TypeError): state.push is not a function in Redux Thunk

Learn how to fix the common Redux Thunk error caused by incorrect state assignment. This post breaks down the problem and provides a clear solution to ensure smooth state management in your React applications.
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Understanding the Issue with Redux Thunk State Management

If you've encountered the error Unhandled Rejection (TypeError): state.push is not a function while using Redux Thunk in your React application, you're not alone. This issue commonly arises due to an incorrect state structure. In this guide, we'll explore the root cause of this error and walk you through the solution in manageable steps.

The Background of the Problem

When you're working with Redux Thunk, proper management of your application's state is crucial. In this scenario, the error occurs because of how the state is being set when you retrieve data from the API.

What Happens When the State Mutates?

Initial State: Your initial state is set as an empty array:

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Fetching Data: During the fetching process of dictionary data, you make an API call to https://vocabulary-app-be.herokuapp.c.... The response from this API is an object, not an array, structured like this:

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Mutating State: When you update the state with the action payload that contains the dictionary data, you inadvertently change the structure of your state from an array to an object. This is because the action's payload is an object containing the dictData key, leading to issues when trying to use array methods like push.

The Solution: Correctly Structuring Your State

To resolve this issue, you need to adjust your Redux Thunk logic so that you're directly updating the state with the dictionary data array, rather than an object. Here's how:

Step 1: Modify the Async Thunk

Change your getDictionaryAsync function so that it returns just the data property from the fetched JSON object. Update your existing code from this:

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to:

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Complete Async Thunk Code

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Step 2: Adjust the Reducer

Next, modify your extraReducers section within your slice definition to accept the new payload structure. Change it from setting state directly to this:

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Complete Reducer Code

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Conclusion

By ensuring that your actions directly return the desired data structure, you maintain the integrity of your state management without risking type errors. Redux Thunk can be complex, but by correctly managing how you handle your state, you can simplify your debugging process and enhance the performance of your React applications.

Key Takeaway

Ensure that when you're dealing with Redux states and API responses, you align the expected data structures for smooth and dependable state management.

If you continue to face issues or have any further questions regarding Redux Thunk or state management in your React projects, feel free to leave a comment below!