Скачать или смотреть How to Achieve Automatic snake_case to camelCase Serialization in NestJS

Learn how to automatically serialize JSON request/response from `snake_case` to `camelCase` in NestJS using class-transformer and MikroORM's mapResult method.
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This video is based on the question https://stackoverflow.com/q/62980087/ asked by the user 'Dave Nathanael' ( https://stackoverflow.com/u/9918007/ ) and on the answer https://stackoverflow.com/a/62991696/ provided by the user 'Martin Adámek' ( https://stackoverflow.com/u/3665878/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Transforming snake_case to camelCase in NestJS

If you've ever worked with NestJS and encountered the need to interact with third-party APIs or databases that utilize the snake_case naming convention, you might have faced the challenge of converting these keys to camelCase when dealing with JSON request and response bodies within your controllers.

In this post, we'll explore an efficient way to achieve automatic serialization and deserialization in NestJS - enabling seamless handling of different naming conventions without redundant code.

Understanding the Problem

When building your NestJS application, especially with ORM libraries like MikroORM, you may desire a consistent naming convention across different layers of your application. Commonly, the JSON request bodies sent to your backend might use snake_case, while your JavaScript or TypeScript code typically uses camelCase.

Here’s a brief illustration of the issue:

Incoming Request Body Example (using snake_case):

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

Desired Internal Representation (using camelCase):

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

You can manually map these fields, but that can quickly become tedious and repetitive.

The Solution: Utilizing MikroORM’s mapResult Method

Instead of using decorators like @ Expose, you can streamline the process by leveraging MikroORM's mapResult() method. This allows for automatic conversion of your database results from snake_case to camelCase. Here’s how you can implement this solution.

Step-by-Step Implementation

Define Your Entity:
Ensure your entity is structured correctly to utilize the benefits of MikroORM. Here’s an example of defining the Recipe entity:

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

Use the mapResult() Method:
When you receive data in the snake_case format, utilize the mapResult() method to transform it appropriately:

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

Verify Your Implementation:
After implementing your controller method, ensure your logs or unit tests confirm that the data structure has now changed to camelCase:

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

Conclusion

By using MikroORM’s mapResult() method, you can automatically and efficiently convert your request bodies from snake_case to camelCase, thus maintaining cleaner and more manageable code. This method eliminates the need for repetitive DTOs or manual mapping, allowing you to focus on building your application logic instead.

Don’t let naming conventions slow you down in your NestJS development. Embrace the power of automated serialization and streamline your code for a better development experience.

If you have any questions or need further clarification, feel free to reach out. Happy coding!