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Discover how to fix the issue with `Kotlin Gson toJson` returning double quoted strings when encoding JSON objects. Explore the right practices for using Retrofit and Gson with your Kotlin classes.
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Understanding the Kotlin Gson toJson Issue: Avoiding Double Quoted Strings

When working with JSON in Kotlin, using the Gson library is quite common for encoding and decoding JSON objects. However, a common issue that developers face is the output of double-quoted strings when using Gson.toJson(). In this post, we will explore why this issue occurs and how to resolve it effectively.

The Problem: Double Quoted Strings

Imagine you are trying to encode a JSON object from a Kotlin class using Gson, like so:

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

After encoding, you might notice that the result is wrapped in double quotes:

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

However, what you were expecting was:

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

This discrepancy can be quite frustrating. So, let’s delve into the reasons behind this behavior.

The Root Cause: Incorrect Use of Retrofit

The issue often arises not from Gson itself but from how you handle this encoded data when sending it to a server, particularly with Retrofit. Many developers attempt to send their JSON strings directly as follows:

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

In this scenario, the requestJson is already a JSON string when passed to the @ Body, resulting in it being encapsulated again in quotes.

The Solution: Directly Passing the Object

To avoid this issue, the correct approach is to pass the object directly without encoding it into a JSON string. The Retrofit library, in conjunction with Gson, can handle the conversion for you. Here’s how to implement it properly:

Step 1: Adjust Your AuthService Interface

Change your AuthService interface to accept the RequestData object directly:

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

Step 2: Use the Data Class Directly

Instead of converting the data class to a JSON string, simply use it like this:

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

Conclusion

In summary, the Kotlin Gson toJson() method may lead to unexpected results if not correctly integrated with Retrofit for network requests. Always ensure that you’re passing data types expected by your API interface rather than pre-encoding them into strings. By using the approach outlined above, you can avoid the double-quoted string issue and ensure that your JSON objects are constructed correctly.

This practice not only enhances code readability but also keeps your interactions with APIs clean and efficient. If you have encountered this issue, try implementing the proper method outlined here, and you should see improved results in your Kotlin applications.