Solution Approach
To improve error handling, we can create a custom error class called UserNotFoundError that extends the Error class. This custom error class will convey the specific information that the requested user was not found.
Let’s define the UserNotFoundError class:
Javascript
class UserNotFoundError extends Error { constructor(userId: string) { super(`User not found with ID: ${userId}`); this.name = 'UserNotFoundError'; } } |
In this code snippet, we define the UserNotFoundError class that extends the Error class. The constructor of the UserNotFoundError class takes the userId as a parameter and calls the parent Error class constructor with a specific error message that includes the ID of the user. We also set the name property of the error instance to “UserNotFoundError”.
Next, we modify our code to throw an instance of UserNotFoundError instead of a generic Error:
Javascript
function getUserById(req: Request, res: Response) { const userId = req.params.id; const user = findUserById(userId); if (!user) { throw new UserNotFoundError(userId); } res.json(user); } |
Now, when a user with an invalid ID is requested, the server throws an instance of UserNotFoundError, providing a clear and informative error message.
Output (Desired):
Output
In the desired output, the error message indicates the specific error type (UserNotFoundError) and includes the ID of the user that was not found. This information helps in identifying the exact error in the code.
TypeScript Custom Errors in RESTful API
In this article, we will explore the importance of using custom error handling in TypeScript for RESTful APIs. We will begin by highlighting the problem statement, followed by demonstrating the problem with code examples and error outputs. Finally, we will present a solution approach using custom error classes and showcase the desired output. By the end, you will have a clear understanding of how to implement custom errors to improve error handling in your TypeScript-based RESTful APIs.
Contact Us