Скачать или смотреть How to Successfully Pass TypeScript Arrays with Axios to Your Java Backend

A detailed guide on how to pass a TypeScript object containing an array to a Java backend using Axios, while troubleshooting common issues with array initialization.
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Passing TypeScript Objects with Arrays Using Axios

In modern web development, the interplay between frontend and backend technologies is pivotal. If you're working with TypeScript on the front end and Java on the backend, you may find yourself needing to pass complex data structures like objects containing arrays. In this post, we will break down how to pass a TypeScript object with an array to your Java backend using Axios. Along the way, we will address common pitfalls that may arise in the process.

The Problem

Consider a scenario where you have an object in TypeScript that includes an array of strings, and you want to send this object to your Java backend using Axios for further processing. A common issue arises when the way you initialize the array impacts its behavior when data is sent over the network.

Example of Array Initialization

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When you initialize an array like this, everything seems to work perfectly. However, if you initialize it as follows:

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

Then add elements via a loop:

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

You may find that the backend receives an empty array. This is not just frustrating, but it can also lead to confusion, especially considering that initializing the array with values, followed by adding more, leads to only the static values being retrieved on the Java side.

The Solution

After some troubleshooting, the issue turned out to be related to the timing of when the data was sent versus when the array was populated.

Identifying the Root Cause

The core of the problem lay in the data source for filling the array. The data was being read from an external file using the FileReader. If the API request is made before the array is completely filled, it results in the backend receiving an empty array.

How to Ensure Proper Data Flow

To ensure your Java backend receives all the required data, follow these steps:

Load Your Data Properly: Make sure to handle asynchronous file loading correctly. Use the onload function of the FileReader to ensure that the array is fully filled before making the API call.

Structure Your API Request: Once your data is ready, only then should you initiate the API request to pass your TypeScript object with the populated array.

Here’s a refined version of your API request function:

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

Important Notes

Always make sure that asynchronous operations are completed before proceeding with dependent actions.

Use error handling to catch issues with array initialization or API requests.

Conclusion

Passing complex objects containing arrays from TypeScript to a Java backend using Axios can seem daunting, but by understanding your data flow and ensuring that your arrays are properly initialized and populated, you can avoid many common pitfalls. Always test your flow and ensure that your data is ready before sending out requests, and you'll find that integration between your frontend and backend becomes much smoother.

If you encountered similar issues or have additional tips, feel free to share in the comments!