Nest.js 拦截器

Docs: https://docs.nestjs.com/interceptors

该对象包含从路由处理程序返回的值

在方法执行之前/之后绑定额外的逻辑

转换函数返回的结果

转换从函数抛出的异常

// logging.interceptor.ts

import { ExecutionContext, Injectable, NestInterceptor, HttpException, HttpStatus } from '@nestjs/common';
import { Observable, throwError, of } from 'rxjs';
import { tap, map, catchError } from 'rxjs/operators';

@Injectable()
export class LoggingInterceptor implements NestInterceptor {
  intercept(context: ExecutionContext, call$: Observable<any>): Observable<any> {
    const now = Date.now();

    if(true){ // 硬编码，直接返回 []
      return of([])
    }
    return call$.pipe(

      catchError(err => {
        return throwError(new HttpException('拦截错误', HttpStatus.BAD_GATEWAY))
      }),

      tap(() => {
        console.log(`${Date.now() - now}ms`);
      }),

      map((data) => {

        // data 为路由的返回值
        console.log(data)
        return data
      })
    );
  }
}

5到6变化

// Before
@Injectable()
export class TransformInterceptor implements NestInterceptor {
  intercept(
    context: ExecutionContext,
    call$: Observable<T>,
  ): Observable<Response<T>> {
    return call$.pipe(map(data => ({ data })));
  }
}

// After
@Injectable()
export class TransformInterceptor implements NestInterceptor {
  intercept(
    context: ExecutionContext,
    next: CallHandler,
  ): Observable<Response<T>> {
    return next
      .handle()
      .pipe(map(data => ({ data })));
  }
}