- What Is Middleware?
- Middleware is a piece of code that runs before a request is completed. It acts as a bridge between the incoming request and your application.
- By leveraging middleware, you gain flexibility and control over how requests are handled and responses are modified.
- Use Cases for Middleware:
- Authentication and Authorization: Middleware ensures user identity and checks session cookies before granting access to specific pages or API routes.
- Server-Side Redirects: You can redirect users at the server level based on conditions (e.g., locale or user role).
- Path Rewriting: Dynamically rewrite paths to API routes or pages based on request properties (useful for A/B testing or legacy paths).
- Bot Detection: Protect your resources by detecting and blocking bot traffic.
- Logging and Analytics: Capture and analyze request data before processing by the page or API.
- Feature Flagging: Enable or disable features dynamically for seamless rollouts or testing.
- When to Be Mindful of Middleware
- :Complex Data Fetching and Manipulation: Middleware isn’t designed for direct data fetching or manipulation; use route handlers or server-side utilities instead.
- Heavy Computational Tasks: Keep middleware lightweight to avoid delays in page load. For heavy computations, use dedicated route handlers.
- Extensive Session Management: While basic session tasks can be handled by middleware, extensive session management should be done elsewhere.
- Direct Database Operations: Avoid performing direct database operations within middleware; use route handlers or server-side utilities.
- Convention for Defining Middleware:Create a file named
middleware.ts(or.js) in the root of your project. - Organize middleware logic modularly by breaking out functionalities into separate files and importing them into the main
middleware.ts. - Enforce a single middleware file to simplify configuration, prevent conflicts, and optimize performance.