I’m thrilled to introduce a new lightweight package aimed at simplifying error management in Next.js applications: nextjs-centralized-error-handler. As developers, we often encounter challenges with error handling, especially within frameworks like Next.js, where traditional methods can lead to repetitive code and overlooked scenarios.
Drawing inspiration from my experience with the Yii2 framework—where built-in error classes streamline error management without the need to hardcode status codes or messages—I recognized a similar need in the Node.js ecosystem. This realization prompted the development of custom error classes within this package, enhancing both consistency and usability.
Important Note: This package is currently in beta. As a newly released tool, your feedback is essential for identifying potential issues and improving its stability. I encourage you to try out the nextjs-centralized-error-handler package and share your insights, whether through bug reports or suggestions for improvement. Together, we can strengthen this package for the Next.js community.
Install the Package
npm install nextjs-centralized-error-handler # or yarn add nextjs-centralized-error-handler
Wrap Your API Route Handler
// pages/api/example.js
const { errorHandler, BadRequestError } = require('nextjs-centralized-error-handler');
const handler = async (req, res) => {
if (!req.body.name) {
throw new BadRequestError('Name is required.');
}
res.status(200).json({ message: 'Success' });
};
export default errorHandler(handler);
Customize Error Handling (Optional)
npm install nextjs-centralized-error-handler # or yarn add nextjs-centralized-error-handler
Next.js 13’s middleware offers powerful global interception capabilities, ideal for tasks like authentication and general request validation. However, nextjs-centralized-error-handler enhances error handling by providing fine-grained, route-level control and detailed responses that middleware alone does not cover. Here’s how this package complements and extends Next.js middleware:
Route-Specific Error Management: With nextjs-centralized-error-handler, each route can define its own contextual error handling, with tailored messages that match the route’s functionality. This modularity is essential for complex applications with varied error handling needs across different endpoints.
Custom Error Classes with Detailed Responses: The package introduces custom error classes (e.g., BadRequestError, UnauthorizedError) with structured, frontend-friendly JSON responses. These responses are enriched with metadata like status codes and error types, ensuring predictable and standardized error handling for backend and frontend teams.
Enhanced Security and Data Privacy: Only errors that are intentional instances of CustomError have their status codes and messages sent to the client. For unexpected errors, a generic error message is used, and sensitive details are kept server-side, minimizing information leakage.
Logging and Integration with Monitoring Tools: Supports integration with logging services (e.g., Sentry, Datadog), enabling detailed error tracking and debugging beyond what middleware alone can achieve.
Customizable and Extensible Error Handling: The CustomError class is fully extensible, allowing developers to define application-specific errors, creating flexible error-handling strategies as applications evolve.
By combining Next.js middleware with nextjs-centralized-error-handler, you achieve a robust and flexible error-handling solution that supports both global and route-specific needs.
Next.js 13 introduces global middleware, enabling request-level interception for tasks such as authentication and general validation. Below is a comparison showing how Next.js 13 middleware differs from nextjs-centralized-error-handler and when to use each.
Next.js 13 middleware can be defined globally and applied across all routes that match a specified pattern. This is useful for high-level operations like logging or authorization.
npm install nextjs-centralized-error-handler # or yarn add nextjs-centralized-error-handler
While Next.js middleware is useful for global, high-level tasks, nextjs-centralized-error-handler enables route-specific error handling with custom error classes for fine-grained control. Here’s how both work together:
| Feature | Next.js 13 Middleware | nextjs-centralized-error-handler |
|---|---|---|
| Scope | Global, based on route pattern matching | Route-specific, applied individually to each handler |
| Use Case | Authentication, global request validation | Detailed error handling, custom error messages |
| Custom Error Responses | Limited, generalized JSON responses | Structured, frontend-compatible JSON responses |
| Custom Error Classes | ❌ | ✅ |
| Error Logging Integration | ❌ | ✅ (supports Sentry, Datadog, etc.) |
| Fine-Grained Control | ❌ | ✅ |
| Preventing Information Leakage | Limited, as it handles errors globally without distinguishing between error types | Enhanced, distinguishes between custom and unexpected errors to prevent sensitive data exposure |
| Integration with Route Handlers | Middleware runs before route handlers, cannot modify responses within handlers | Wraps individual route handlers, allowing for customized responses per route |
| Extensibility | Limited to what middleware can handle globally | Highly extensible through custom error classes and configurable options |
While Next.js middleware provides a powerful mechanism for high-level request interception, it’s important to note that middleware operates before the execution of the route handler. This means that any exceptions thrown inside the handler will not be caught by the middleware; instead, this will lead to a generic 500 Internal Server Error being returned to the client. In contrast, nextjs-centralized-error-handler excels at fine-grained error handling within individual API routes. This section clarifies their distinct roles and demonstrates how they can be used together effectively.
Imagine you are building an API route that requires a user's name to be provided in the request body. If the name is missing, you want to respond with a clear and specific error message. Let's see how each approach handles this scenario.
In Next.js, middleware can be used to validate requests globally. However, it cannot catch exceptions thrown within individual route handlers.
npm install nextjs-centralized-error-handler # or yarn add nextjs-centralized-error-handler
// pages/api/example.js
const { errorHandler, BadRequestError } = require('nextjs-centralized-error-handler');
const handler = async (req, res) => {
if (!req.body.name) {
throw new BadRequestError('Name is required.');
}
res.status(200).json({ message: 'Success' });
};
export default errorHandler(handler);
What Happens Here:
In contrast, nextjs-centralized-error-handler provides a higher-order function that captures errors thrown in route handlers.
const handler = async (req, res) => {
// Your logic here
};
const options = {
logger: customLoggerFunction,
defaultMessage: 'Something went wrong!',
formatError: (error, req) => ({
message: error.message,
type: error.name,
timestamp: new Date().toISOString(),
}),
};
export default errorHandler(handler, options);
What Happens Here:
Combining both Next.js middleware and nextjs-centralized-error-handler provides a comprehensive error-handling strategy:
Middleware (middleware.js):
npm install nextjs-centralized-error-handler # or yarn add nextjs-centralized-error-handler
Route Handler (pages/api/example.js):
// pages/api/example.js
const { errorHandler, BadRequestError } = require('nextjs-centralized-error-handler');
const handler = async (req, res) => {
if (!req.body.name) {
throw new BadRequestError('Name is required.');
}
res.status(200).json({ message: 'Success' });
};
export default errorHandler(handler);
Explanation:
By using Next.js middleware for request-level checks and nextjs-centralized-error-handler for response-level error handling, you achieve both broad validation and fine-grained error management.
In traditional Node.js/Express applications, centralized error handling is often managed through middleware, which intercepts requests and errors consistently across routes. In Next.js, however, API routes don’t support middleware in the same way, creating challenges for centralized error handling. nextjs-centralized-error-handler fills this gap by using a higher-order function to provide route-specific error handling across all API routes.
In Express, centralized error handling is achieved through middleware functions, which allow for reusable error management across routes:
const handler = async (req, res) => {
// Your logic here
};
const options = {
logger: customLoggerFunction,
defaultMessage: 'Something went wrong!',
formatError: (error, req) => ({
message: error.message,
type: error.name,
timestamp: new Date().toISOString(),
}),
};
export default errorHandler(handler, options);
In this approach, errors are passed to next(error), which then triggers centralized error-handling middleware to respond consistently across routes.
With nextjs-centralized-error-handler, you get middleware-like behavior tailored for Next.js through a higher-order function (errorHandler) that wraps route handlers, intercepting and managing errors at the route level:
npm install nextjs-centralized-error-handler # or yarn add nextjs-centralized-error-handler
With nextjs-centralized-error-handler, you avoid repetitive error-handling code in each route. Instead, custom error classes and the errorHandler higher-order function provide centralized, consistent error responses, simplifying maintenance and extending error handling across the entire application.
Error handling ensures that an application can respond to unexpected conditions (e.g., invalid input, lack of access) gracefully. Instead of crashing, an application with robust error handling will provide helpful feedback to users and log errors for debugging.
Next.js API routes support a global middleware approach, but they don’t natively support route-specific, fine-grained error handling like Express. Each route handler would otherwise need individual error management, leading to redundant code and inconsistent error responses. nextjs-centralized-error-handler addresses this by providing a higher-order function, errorHandler, that wraps route handlers to ensure consistent and centralized error handling at the route level.
npm install nextjs-centralized-error-handler # or yarn add nextjs-centralized-error-handler
// pages/api/example.js
const { errorHandler, BadRequestError } = require('nextjs-centralized-error-handler');
const handler = async (req, res) => {
if (!req.body.name) {
throw new BadRequestError('Name is required.');
}
res.status(200).json({ message: 'Success' });
};
export default errorHandler(handler);
Import errorHandler and custom error classes into your Next.js API route:
const handler = async (req, res) => {
// Your logic here
};
const options = {
logger: customLoggerFunction,
defaultMessage: 'Something went wrong!',
formatError: (error, req) => ({
message: error.message,
type: error.name,
timestamp: new Date().toISOString(),
}),
};
export default errorHandler(handler, options);
The package includes several predefined error classes:
These classes simplify error creation without hardcoding status codes in each route:
// middleware.js (placed at the root of the app)
import { NextResponse } from 'next/server';
export function middleware(req) {
// Example of request validation or general logging
if (!req.headers.get('Authorization')) {
return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
}
return NextResponse.next(); // Continue to the route handler
}
// Optional: Configure route matching
export const config = {
matcher: '/api/:path*', // Applies middleware only to /api/* routes
};
If you simply instantiate an error without specifying a message, it defaults to a pre-defined, user-friendly message.
// middleware.js
import { NextResponse } from 'next/server';
export function middleware(req) {
try {
// You can include any logic here that might throw an error
return NextResponse.next(); // Proceed to the route handler
} catch (error) {
// Handle the error and return an appropriate response
return NextResponse.json({ error: 'An error occurred while processing your request.' }, { status: 500 });
}
}
To address specific needs beyond predefined classes, the package is designed to be extensible, allowing you to create unique custom errors for advanced use cases. You can extend the base CustomError class to define your own error types, tailored to specific business logic. Here are some examples of custom errors you might create:
// pages/api/example.js
const handler = async (req, res) => {
if (!req.body.name) {
throw new Error('Name is required.'); // This will not be caught by middleware
}
res.status(200).json({ message: `Hello, ${req.body.name}!` });
};
export default handler;
This example defines a custom ConflictError (HTTP 409), which can be thrown in cases where a resource conflict occurs. Creating custom errors allows you to handle unique business logic or application-specific needs efficiently.
In addition to supporting traditional API routes, nextjs-centralized-error-handler can also be utilized with the App Router introduced in Next.js 13. Here’s how to implement error handling in your App Router using the package.
You can create a route in your App Router and use the error handler to manage errors effectively.
npm install nextjs-centralized-error-handler # or yarn add nextjs-centralized-error-handler
Using the App Router allows for a clean and structured way to manage errors while leveraging the powerful capabilities of nextjs-centralized-error-handler. By combining both, you ensure that your application handles errors effectively, regardless of the routing method used.
Beyond custom errors, this package allows developers to fully control the behavior of error handling by:
You can configure the errorHandler with options for custom logging, error formatting, and default messages:
// pages/api/example.js
const { errorHandler, BadRequestError } = require('nextjs-centralized-error-handler');
const handler = async (req, res) => {
if (!req.body.name) {
throw new BadRequestError('Name is required.');
}
res.status(200).json({ message: 'Success' });
};
export default errorHandler(handler);
The formatError function is highly flexible, allowing you to create detailed and structured error responses that fit your application’s requirements. Below are some example configurations showcasing the versatility of formatError:
const handler = async (req, res) => {
// Your logic here
};
const options = {
logger: customLoggerFunction,
defaultMessage: 'Something went wrong!',
formatError: (error, req) => ({
message: error.message,
type: error.name,
timestamp: new Date().toISOString(),
}),
};
export default errorHandler(handler, options);
// middleware.js (placed at the root of the app)
import { NextResponse } from 'next/server';
export function middleware(req) {
// Example of request validation or general logging
if (!req.headers.get('Authorization')) {
return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
}
return NextResponse.next(); // Continue to the route handler
}
// Optional: Configure route matching
export const config = {
matcher: '/api/:path*', // Applies middleware only to /api/* routes
};
// middleware.js
import { NextResponse } from 'next/server';
export function middleware(req) {
try {
// You can include any logic here that might throw an error
return NextResponse.next(); // Proceed to the route handler
} catch (error) {
// Handle the error and return an appropriate response
return NextResponse.json({ error: 'An error occurred while processing your request.' }, { status: 500 });
}
}
The formatError function provides the flexibility to add or omit fields based on your requirements, making it easy to generate structured, informative error responses. These options make the package adaptable to diverse applications by providing developers the ability to standardize error messaging and traceability across their API.
The errorHandler higher-order function wraps each route handler individually, capturing all exceptions—both expected and unexpected—without requiring repetitive try-catch blocks. This approach ensures that even third-party or unforeseen errors are intercepted, allowing for consistent and secure error responses across all routes.
To protect sensitive data, our package distinguishes between intentional, known errors (e.g., CustomError instances) and unexpected errors:
Custom Errors Only: Only errors created as instances of CustomError (or its subclasses) include their statusCode and message in the client response, providing clear, user-friendly error feedback for known issues.
Generic Handling of Unexpected Errors: For errors that aren’t instances of CustomError—such as third-party library issues or unforeseen server errors—errorHandler automatically applies a status code of 500 and a generic message ("An internal server error occurred"). This prevents sensitive information from being inadvertently exposed to clients.
While keeping responses to the client secure and generalized, errorHandler also supports server-side logging. This allows unexpected errors to be logged and monitored internally without revealing details to the client, combining security with effective error tracking.
Consider an API route that relies on a third-party library, which may throw errors we can’t predict:
npm install nextjs-centralized-error-handler # or yarn add nextjs-centralized-error-handler
If thirdPartyLibrary.doSomething() throws an error that isn’t a CustomError, errorHandler will:
The errorHandler function distinguishes between custom errors and unexpected errors:
By catching all errors in this way, nextjs-centralized-error-handler provides a robust, secure, and unified error-handling solution tailored for Next.js applications, with built-in protections to prevent unintended data exposure.
Below are real-world scenarios demonstrating how nextjs-centralized-error-handler can simplify error handling across various use cases.
Note: If an error is instantiated without a specific message, a default, user-friendly message is provided automatically.
Use Case: Ensure that only specific HTTP methods (e.g., POST) are allowed for an API route and provide a meaningful error message if the method is incorrect.
In this example, MethodNotAllowedError is thrown if the incoming request uses any method other than POST, ensuring consistent, user-friendly feedback. If no custom message is provided, the default message, "Method not allowed," will be used.
npm install nextjs-centralized-error-handler # or yarn add nextjs-centralized-error-handler
Use Case: Check for the presence of required parameters in the request and respond with a structured error if validation fails.
Here, BadRequestError is thrown when a required parameter (name) is missing. If no custom message is specified, the default message, "It seems there was an error with your request," is used.
// pages/api/example.js
const { errorHandler, BadRequestError } = require('nextjs-centralized-error-handler');
const handler = async (req, res) => {
if (!req.body.name) {
throw new BadRequestError('Name is required.');
}
res.status(200).json({ message: 'Success' });
};
export default errorHandler(handler);
Use Case: Restrict access to authorized users only. If the user is not authenticated, respond with an UnauthorizedError to signal unauthorized access.
In this example, UnauthorizedError is used to ensure only authenticated users can access the route. If no custom message is provided, it defaults to "Unauthorized access. Please log in."
const handler = async (req, res) => {
// Your logic here
};
const options = {
logger: customLoggerFunction,
defaultMessage: 'Something went wrong!',
formatError: (error, req) => ({
message: error.message,
type: error.name,
timestamp: new Date().toISOString(),
}),
};
export default errorHandler(handler, options);
Use Case: Reject requests that contain a payload exceeding a defined size, helping to prevent misuse or denial-of-service attacks.
If the payload exceeds a specific limit, PayloadTooLargeError is thrown to inform the client. Without a custom message, the default message, "Request entity too large," will be displayed.
// middleware.js (placed at the root of the app)
import { NextResponse } from 'next/server';
export function middleware(req) {
// Example of request validation or general logging
if (!req.headers.get('Authorization')) {
return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
}
return NextResponse.next(); // Continue to the route handler
}
// Optional: Configure route matching
export const config = {
matcher: '/api/:path*', // Applies middleware only to /api/* routes
};
If you want to include additional metadata or customize error responses, nextjs-centralized-error-handler allows you to define a formatError function. This function can be tailored to include extra fields, such as request paths or timestamps.
For full details, see the Customizing Error Handling Behavior section. Here's a quick example:
// middleware.js
import { NextResponse } from 'next/server';
export function middleware(req) {
try {
// You can include any logic here that might throw an error
return NextResponse.next(); // Proceed to the route handler
} catch (error) {
// Handle the error and return an appropriate response
return NextResponse.json({ error: 'An error occurred while processing your request.' }, { status: 500 });
}
}
To enhance observability, nextjs-centralized-error-handler supports custom logging through any service, such as Sentry, Datadog, or a custom logging solution. By passing a logging function (such as Sentry.captureException) to errorHandler, you can monitor errors in real-time while ensuring security and efficiency.
A "custom logger" is any logging function or external service (such as console.log, Sentry.captureException, or a custom implementation) that you provide to errorHandler to log errors server-side. This logging function is not part of nextjs-centralized-error-handler itself, but the package is designed to integrate seamlessly with the logger of your choice.
If you’re using Sentry, a popular monitoring tool, you can integrate it with this package for production error tracking:
Note on Sentry: Sentry helps developers track, debug, and resolve issues in real time. Integrating Sentry with nextjs-centralized-error-handler allows you to log errors in production, providing insight into where and why failures occur without exposing sensitive details.
The example below demonstrates how to use Sentry’s captureException function as a logger with errorHandler.
npm install nextjs-centralized-error-handler # or yarn add nextjs-centralized-error-handler
This setup captures errors for monitoring, while safeguarding against exposing sensitive information to clients. By leveraging custom loggers, nextjs-centralized-error-handler combines robust security with effective error tracking, ensuring a secure and observable application environment.
As this package is newly released, I am aware of the importance of stability in production environments. While I have conducted testing, the real-world usage and feedback from the community are crucial for identifying any potential issues and improving the package further.
I encourage developers to integrate nextjs-centralized-error-handler into their projects and share their experiences. Whether it’s bug reports, suggestions for improvement, or simply sharing how it has helped streamline error management in your applications, your feedback is invaluable. Together, we can enhance this package and make it even more effective for the Next.js community.
I hope that nextjs-centralized-error-handler will greatly enhance error management for Next.js developers, offering a comprehensive and user-friendly approach to handling errors. By centralizing error management, leveraging custom error classes, and integrating smoothly with logging services, this package tackles common pain points in Next.js application development.
I invite the dev.to community to provide feedback and contribute to the project, as your insights are invaluable for refining this package. You can check out the package on npm and explore the GitHub repository for further details!
Explore the package and contribute to its development:
Your input is crucial for identifying issues and enhancing stability. I encourage you to experiment with nextjs-centralized-error-handler and share your experiences. Together, we can advance this package for the Next.js community.
Thank you for your support, and I’m excited to hear your thoughts and experiences!
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