Using @RequestBody to Map JSON to a Class with @Builder in Spring

---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Use @RequestBody to map JSON to a class with @Builder

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Using @RequestBody to Map JSON to a Class with @Builder in Spring

In modern web applications, handling JSON data efficiently is crucial. One common task in a Spring application is mapping a JSON request body to a Java class. This is typically done using the @RequestBody annotation. However, developers occasionally face challenges when leveraging the @Builder annotation from Lombok. If you've encountered a situation where your POST request works fine initially but fails once you add the @Builder annotation, you're not alone. In this guide, we’ll explore how to effectively use both @RequestBody and @Builder together in your Spring Boot applications.

The Problem

You have implemented a REST API where you're using the @RequestBody annotation to receive JSON payloads in your controller method. However, when you augment your model class (in this case, Card) with the @Builder annotation, you encounter issues during request processing. This can lead to failure in mapping the incoming JSON data to your class, resulting in error responses and unexpected behavior.

Here is a snippet of your current controller code:

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

And your model class looks like this:

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

The Solution

To resolve this issue, you need to ensure that your class can be instantiated correctly when Spring tries to bind the JSON data to it. The @Builder annotation alone does not create a default constructor, which is necessary for Spring to instantiate the class with the data it receives. By adding the @NoArgsConstructor and @AllArgsConstructor annotations from Lombok, you can solve this problem effectively.

Step 1: Update the Model Class

You need to modify your Card class to include these two additional annotations:

@NoArgsConstructor: This annotation generates a constructor with no arguments.

@AllArgsConstructor: This annotation generates a constructor that accepts one argument for each field in the class.

Here’s how your updated Card class should look:

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

Step 2: What Each Annotation Does

@Data: Generates boilerplate code like getters, setters, toString, etc.

@Builder: Provides a builder pattern for creating instances of Card without needing to specify parameters in order.

@NoArgsConstructor: Allows the framework to create an instance of Card without needing any constructor arguments, which is essential for deserialization.

@AllArgsConstructor: This can be handy if you need to create instances easily in other parts of your application.

Step 3: Verify Your Controller

Make sure your controller remains as it originally was, with no additional changes needed in the method signature:

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

Conclusion

Using the @RequestBody to map JSON data in Spring is straightforward when you have the correct setup. By incorporating @NoArgsConstructor and @AllArgsConstructor along with @Builder, you ensure that your classes can be instantiated properly, enabling smooth deserialization of JSON payloads.

By following the steps outlined above, you can easily overcome the issues related to using @Builder with @RequestBody. Now you can move forward with confidence, mapping your JSON data to Java objects seamlessly in your Spring applications!

If you have any further questions or need additional assistance, feel free to reach out or leave a comment below. Happy coding!