Questions
3 of 5
1What is the difference between UseGuards, UseInterceptors, UsePipes, and UseFilters — can they all be applied at the same levels?
2How do you test a guard, interceptor, or pipe in isolation using TestingModule in NestJS?
3What is ExecutionContext in NestJS and why is it central to guards, interceptors, and filters?
4What is the binding order precedence when the same enhancer type is applied at global, controller, and method level in NestJS?
5What is the complete NestJS request lifecycle in order?
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03 / 05

What is ExecutionContext in NestJS and why is it central to guards, interceptors, and filters?

ExecutionContext extends ArgumentsHost and provides metadata about the current execution — the transport type (HTTP, WebSocket, RPC) and which handler and class will process it. Its getHandler() and getClass() methods are used with Reflector to read @SetMetadata() values for RBAC and feature flags.

ExecutionContext methods and transport switching
Why ExecutionContext is central:
  1. 1

    getHandler() and getClass() give guards and interceptors access to the matched route metadata.

  2. 2

    switchToHttp(), switchToWs(), switchToRpc() make enhancers transport-agnostic.

  3. 3

    Used by Reflector to read @SetMetadata() values — essential for RBAC, @Public(), feature flags.

  4. 4

    ArgumentsHost (parent interface) is used by exception filters; ExecutionContext extends it with handler/class info.