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

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

canActivate(ctx: ExecutionContext): boolean { // Determine transport type const type = ctx.getType(); // 'http' | 'ws' | 'rpc' // Switch to the right context const req = ctx.switchToHttp().getRequest (); const ws = ctx.switchToWs().getClient(); const rpc = ctx.switchToRpc().getData(); // Read route metadata via Reflector const handler = ctx.getHandler(); // method reference const cls = ctx.getClass(); // controller class reference const roles = this.reflector.getAllAndOverride ('roles', [ handler, cls, ]); } getHandler() and getClass() give guards and interceptors access to the matched route metadata. switchToHttp(), switchToWs(), switchToRpc() make enhancers transport-agnostic. Used by Reflector to read @SetMetadata() values — essential for RBAC, @Public(), feature flags. ArgumentsHost (parent interface) is used by exception filters; ExecutionContext extends it with handler/class info.

Difficulty: 6/10

guards, interceptors, 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
getHandler() and getClass() give guards and interceptors access to the matched route metadata.
2
switchToHttp(), switchToWs(), switchToRpc() make enhancers transport-agnostic.
3

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

Difficulty: 6/10

guards, interceptors, 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
getHandler() and getClass() give guards and interceptors access to the matched route metadata.
2
switchToHttp(), switchToWs(), switchToRpc() make enhancers transport-agnostic.
3

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

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

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