Скачать или смотреть Understanding axios Response Issues: Fixing the Undefined Problem

Learn why `axios` may not be returning values correctly and how to resolve the issue in your JavaScript code.
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This video is based on the question https://stackoverflow.com/q/70184048/ asked by the user 'Randy' ( https://stackoverflow.com/u/2012419/ ) and on the answer https://stackoverflow.com/a/70184070/ provided by the user 'Ilijanovic' ( https://stackoverflow.com/u/10990737/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Why Is axios Not Returning Correctly? A Guide to Fixing the Undefined Problem

If you're migrating from the native fetch API to axios in your React application, you might encounter issues where axios returns undefined in your console logs. It can be frustrating when you expected your API call to succeed but found no usable data. In this guide, we'll break down the problem and walk you through a clear solution to ensure that your axios requests return the correct data.

The Problem Breakdown

You might be trying to call an API endpoint using axios similar to how you would do with fetch, and yet you're left with an undefined response when logging the output. Here are key aspects of the initial question posed:

The developer is replacing fetch with axios but is not seeing the expected outcome.

The code indicates that console.log is being used to check the response, yet the expected data is not present.

Confusion arises due to the misuse of response.json() method which is not appropriate for axios.

Solution: Understand axios Responses

Common Issues with axios Responses

The main reason you're encountering an undefined value is that the structure of the axios response differs from that of fetch. In axios, the response is an object that contains a .data property which holds the actual data returned from the server. Here are the steps you should take to correctly retrieve the data using axios:

Check the Response Object:

Instead of using response.json, check the structure of the axios response by logging it:

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

You will see that it has various properties including data, status, statusText, etc.

Access the Data Properly:

To access your API response, you should use:

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

This ensures that you are setting the state with the actual data returned from the API.

Updating Your Code

Here’s how you can revise your code snippet to ensure it works correctly with axios:

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

Conclusion

Transitioning from fetch to axios can introduce confusion, but understanding how to access response data properly clears the air. Always remember to check the structure of your responses when working with different libraries, as they can differ significantly. By identifying the correct property (response.data) to retrieve your data, you'll be on your way to efficiently handling API calls and managing your application state.

If you find yourself stumped again, don't hesitate to log out objects to understand their structure—this simple step can often lead to a swift resolution!