Optimizing Error Handling: Reducing Redundant Try-Catch Blocks

In any application, error handling is critical to maintain stability and reliability. Typically, a common way to handle errors is by using try-catch blocks. While effective, this approach can clutter the code, make it less DRY, decrease readability, and complicate maintenance.

In this post, we will explore a more efficient way to handle errors in a TypeScript OOP-based application using NestJS by leveraging decorators.

The Problem with try-catch Blocks

1. Code Duplication: As the number of methods increases in a class, duplicating the same try-catch blocks across various methods becomes inefficient and harder to manage.
2. Reduced Readability: Nesting try-catch blocks leads to nested code blocks, which can make the code more difficult to read and understand.
3. Poor Exception Propagation: If exceptions are caught too early, they may not propagate to higher layers of the application where they can be handled more appropriately, missing opportunities for centralized error handling.

The Solution: Using Decorators for Error Handling

Instead of repeating try-catch blocks, we can centralize error handling using decorators. This approach keeps the code cleaner, more readable, and easier to maintain.

In NestJS, we can use decorators to intercept method calls and handle errors globally across services. Let's see how we can achieve this.

Step 1: Defining the Error Handling Decorator
Here's how we can create a decorator to handle errors in methods:

This decorator wraps the method execution in a try-catch block.
Any error caught is logged, and an RpcException is thrown to signal an error in a gRPC-based service.
Note: This example uses RpcException, which is specific to gRPC microservices. If you're not using gRPC, you can replace it with an appropriate exception type (e.g., HttpException for HTTP-based services).

Step 2: Using the Decorator in Services
Once the decorator is defined, you can apply it to any service method that needs centralized error handling:

• By adding @HandleErrors() above a method, you ensure that any error occurring within that method will be caught by the decorator and handled appropriately.

Conclusion

By adopting decorators for error handling, you can reduce the number of redundant try-catch blocks in your code, making it cleaner, more readable, and easier to maintain.

Centralizing error handling through decorators helps you:

• Keep your code DRY (Don't Repeat Yourself).
• Handle exceptions more systematically.
• Improve readability and reduce clutter in methods.

In summary, this approach allows you to manage errors more efficiently by handling them at the right level and letting exceptions propagate when necessary. This makes debugging and maintaining your code much simpler.