[Solved] Identify the error in this custom decorator usage and how to fix it:import { SetMetadata } from '@nestjs/common'; function Permissions(permissions: string[]) { return (target: any, key:... | NestJS

NestJS - Guards

Identify the error in this custom decorator usage and how to fix it:

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

function Permissions(permissions: string[]) {
  return (target: any, key: string) => {
    Reflect.defineMetadata('permissions', permissions, target, key);
  };
}

class UserController {
  @Permissions(['read'])
  getUser() {
    return 'user';
  }
}

AThe decorator must be applied to the class, not method

BThe decorator is missing the return type annotation

CThe decorator should use SetMetadata instead of Reflect.defineMetadata

DThe decorator function parameters are incorrect; should include descriptor

Step-by-Step Solution

Solution:

Step 1: Check decorator implementation
The decorator manually calls Reflect.defineMetadata, which works but is not recommended in NestJS.
Step 2: Use NestJS helper for consistency
SetMetadata is the standard NestJS helper that wraps Reflect.defineMetadata and ensures compatibility with Reflector and other NestJS internals.
Final Answer:
The decorator should use SetMetadata instead of Reflect.defineMetadata -> Option C
Quick Check:
Use SetMetadata for custom decorators in NestJS [OK]

Quick Trick: Always use SetMetadata helper for custom decorators [OK]

Common Mistakes:

Using Reflect.defineMetadata directly instead of SetMetadata
Ignoring NestJS decorator conventions
Misunderstanding decorator parameters

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Identify the error in this custom decorator usage and how to fix it:

Step 1: Check decorator implementation

Step 2: Use NestJS helper for consistency

Final Answer:

Quick Check:

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