Implement Caching Using Interceptors

Interceptors in NestJS act as middleware components that intercept the incoming requests and outgoing responses, allowing for custom tasks before or after the request reaches the route handlers. They are versatile and can be employed for logging, authentication, validation, and caching. Interceptors can be applied at different scopes: globally at the controller level or at the method level using decorators, such as @UseInterceptors.

In this lesson, we’ll focus on a specific use case of interceptors: caching responses. We’ll learn how to use CacheInterceptor to optimize and cache responses for improved performance. Caching is a powerful technique to enhance application performance by storing and reusing frequently requested data. Understanding how to leverage interceptors for caching purposes can significantly improve the efficiency and responsiveness of a NestJS application.

Interceptors

Interceptors are middleware-like components in NestJS that can intercept incoming requests and outgoing responses. They provide a way to modify, log, or enhance the request/response objects.

Scopes

Interceptors can be applied globally, at the controller level, or, at the method level, using decorators like @UseInterceptors. Applying an interceptor at the global level affects all incoming requests and outgoing responses across the entire NestJS app. When we apply an interceptor at the controller level, it only affects the routes within that specific controller.

Below is an example showing how to apply MyInterceptor to different scopes: