Log Requests and Responses in Middleware

Implement a logger middleware

Middleware plays a vital role in shaping the behavior of an application’s HTTP requests and responses. In this lesson, we’ll explore NestJS middleware and, more specifically, how to implement a logger middleware.

Middleware in NestJS allows us to intervene in the request-response cycle, performing actions before or after a request is handled. Once implemented, the logger middleware will be a powerful tool for tracking and analyzing incoming requests. This not only aids in debugging but also provides valuable insights into the application’s runtime behavior.

Middleware

In NestJS, middleware acts as a middleman between the client and route handlers. We can use middleware to intercept incoming HTTP requests before the request reaches the route handler or to manipulate the response object before the response is sent back. With middleware, we can perform various cross-cutting operations, like logging, authentication, and error handling.

It’s worth noting that we must call the next() middleware function to pass control to the next middleware in the stack after the current middleware completes the execution.

NestJS provides a NestMiddleware interface, and we can use it to implement a custom middleware. For example, the following is a skeleton of authentication middleware: