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Extension Decorators

Nubie provides a robust way to build custom decorators via two abstract classes:

  • NubieExtensionMethodDecorator — for method-level behaviors (e.g. enforcing headers)
  • NubieExtensionParamDecorator — for parameter-level access (e.g. custom param extractors)

These give you full control over request/response handling without diving into middleware manually.

Method-Level Extension: Header Check​

Create decorators that run before route handlers and access full Express req, res, next.

Example: Require Header Key​

import { Request, Response, NextFunction } from "express";
import {
  NubieExtensionMethodDecorator,
  NubieError,
  HttpStatusCodes,
} from "nubie";

class HeaderDecorator extends NubieExtensionMethodDecorator {
  constructor(public readonly key: string) {
    super();
  }

  async executeAsync(
    req: Request,
    res: Response,
    next: NextFunction
  ): Promise<void> {
    if (req.headers[this.key]) return;
    throw new NubieError(
      "MissingRequiredHeader",
      HttpStatusCodes.BadRequest,
      `${this.key} is missing in request headers`
    );
  }
}

const Header = NubieExtensionMethodDecorator.createDecorator(HeaderDecorator);

export default Header;

Usage​

@HttpGet("/secure-data")
@Header("x-client-id")
async getDataAsync() {

}

If the header x-client-id is missing, the decorator throws a 400 Bad Request with a custom error message.

Param-Level Extension: Custom Parameter Access​

Build custom parameter decorators that return extracted values — like req.params, req.query, etc.

Example: Param Reader​

import { Request, Response, NextFunction } from "express";
import { NubieExtensionParamDecorator } from "nubie";

class ParamDecorator extends NubieExtensionParamDecorator {
  constructor(public readonly param: string) {
    super();
  }

  async executeAsync(req: Request): Promise<unknown> {
    return req.params[this.param];
  }
}

const Param = NubieExtensionParamDecorator.createDecorator(ParamDecorator);

export default Param;

Usage​

@HttpGet("/users/:id")
async getUserAsync(@Param("id") userId: string) {
  console.log("User ID:", userId);
}

Automatically extracts the id param from the URL and injects it into your handler.