The Complete Production SOP: How to Deploy and Run NestJS Custom Decorators & Execution Context Extraction in Autonomous AI Agents

---
name: "nestjs-custom-decorators-metadata"
description: "Create clean parameter decorators to extract authenticated users, IP addresses, and metadata."
metadata:
  author: "NestJS"
  version: "1.0.0"
  runtime_compatibility:
    - "codex"
    - "claude-code"
    - "cursor"
    - "windsurf"
triggers:
  - "create custom decorator nestjs"
  - "@currentuser decorator nestjs"
  - "createparamdecorator nestjs"
permissions:
  fs_read: true
  fs_write: "workspace"
  shell_exec: false
  net_access: false
---

# Execution SOP & Rules
1. Use createParamDecorator((data: unknown, ctx: ExecutionContext) => {
     const req = ctx.switchToHttp().getRequest();
     return data && req.user ? req.user[data as string] : req.user;
   });
2. Consume in controller: @Get('profile') getProfile(@CurrentUser() user: UserEntity) { return user; };
3. For metadata decorators: export const IS_PUBLIC_KEY = 'isPublic'; export const Public = () => SetMetadata(IS_PUBLIC_KEY, true);
4. In global guards, check metadata with reflector.getAllAndOverride<boolean>(IS_PUBLIC_KEY, [ctx.getHandler(), ctx.getClass()]);

import { createParamDecorator, ExecutionContext } from '@nestjs/common';
import { Request } from 'express';
import { UserEntity } from '../../users/entities/user.entity';

export const CurrentUser = createParamDecorator(
  (data: keyof UserEntity | undefined, ctx: ExecutionContext) => {
    const request = ctx.switchToHttp().getRequest<Request & { user?: UserEntity }>();
    const user = request.user;
    if (!user) {
      return null;
    }
    return data ? user[data] : user;
  },
);

import { SetMetadata } from '@nestjs/common';

export const IS_PUBLIC_KEY = 'isPublic';
export const Public = () => SetMetadata(IS_PUBLIC_KEY, true);

import { ExecutionContext } from '@nestjs/common';
import { ROUTE_ARGS_METADATA } from '@nestjs/common/constants';
import { CurrentUser } from './current-user.decorator';

function getParamDecoratorFactory(decorator: Function) {
  class Test {
    public testMethod(@decorator() value: unknown) {}
  }
  const args = Reflect.getMetadata(ROUTE_ARGS_METADATA, Test, 'testMethod');
  return args[Object.keys(args)[0]].factory;
}

describe('CurrentUser Decorator', () => {
  it('should extract the full user object from request', () => {
    const factory = getParamDecoratorFactory(CurrentUser);
    const mockUser = { id: 'usr_123', email: '[email protected]' };
    const mockContext = {
      switchToHttp: () => ({
        getRequest: () => ({ user: mockUser }),
      }),
    } as unknown as ExecutionContext;

    const result = factory(undefined, mockContext);
    expect(result).toEqual(mockUser);
  });
});