InterceptorsContextCreator

Kind: Class

Source: packages/core/interceptors/interceptors-context-creator.ts

Part of: Core

InterceptorsContextCreator resolves the interceptors that apply to a Nest handler, including global, controller-level, and method-level metadata. It converts interceptor classes or instances into concrete NestInterceptor instances using the current module and request context.

Extends: ContextCreator

Methods

Where it refuses work

• InterceptorsContextCreator stops the work with an early return when isEmpty(metadata).
• InterceptorsContextCreator stops the work with an early return when isObject.
• InterceptorsContextCreator stops the work with an early return when !instanceWrapper.
• InterceptorsContextCreator stops the work with an early return when !this.moduleContext.
• InterceptorsContextCreator stops the work with an early return when !moduleRef.
• InterceptorsContextCreator stops the work with an early return when !this.config.

Diagram

mermaid
graph LR
  A[Global Interceptors] --> D[InterceptorsContextCreator.create]
  B[Controller @UseInterceptors] --> D
  C[Handler @UseInterceptors] --> D
  D --> E[createConcreteContext]
  E --> F[getInterceptorInstance]
  F --> G[Module Injectable Wrapper]
  G --> H[NestInterceptor[]]

Usage

ts
import {
  CallHandler,
  ExecutionContext,
  Injectable,
  NestInterceptor,
  UseInterceptors,
} from '@nestjs/common';
import { Observable } from 'rxjs';
import { tap } from 'rxjs/operators';

@Injectable()
export class LoggingInterceptor implements NestInterceptor {
  intercept(context: ExecutionContext, next: CallHandler): Observable<unknown> {
    const handlerName = context.getHandler().name;

    console.log(`Before ${handlerName}`);

    return next.handle().pipe(
      tap(() => console.log(`After ${handlerName}`)),
    );
  }
}

@UseInterceptors(LoggingInterceptor)
export class UsersController {
  findAll() {
    return [];
  }
}

Nest internally uses InterceptorsContextCreator to collect LoggingInterceptor metadata, resolve its injectable instance, and execute it around the controller handler.

AI Coding Instructions

• Preserve interceptor resolution order: global interceptors should be applied before controller- and handler-scoped interceptors.
• Support both interceptor instances ({ intercept() {} }) and interceptor classes resolved through the module injector.
• Return only valid NestInterceptor instances; unresolved providers should be filtered out rather than causing downstream failures.
• Respect request-scoped providers by resolving instances with the active ContextId and optional inquirer identifier.
• When adding interceptor metadata, use Nest’s @UseInterceptors() integration rather than directly constructing this internal context creator.

Relationships

• IMPORTS → INTERCEPTORS_METADATA
• IMPORTS → Controller
• IMPORTS → NestInterceptor
• IMPORTS → Type
• IMPORTS → isEmpty
• IMPORTS → isFunction

Used by

4 references from 4 files. Each is a place in this repository where the symbol is actually used — go read one rather than trusting an example.

Imported by (4)

• RpcHandlerMetadata — packages/microservices/context/rpc-context-creator.ts:35
• MicroservicesModule — packages/microservices/microservices-module.ts:23
• WsHandlerMetadata — packages/websockets/context/ws-context-creator.ts:34
• SocketModule — packages/websockets/socket-module.ts:27