Middlewares

In DolphJS, standard Express middlewares can be seamlessly integrated into your modern, decorator-driven architecture. Middlewares are functions that have access to the request object (req), the response object (res), and the next middleware function in the application’s request-response cycle.

Route-Level Middlewares

To apply a middleware to a specific route, use the @UseMiddleware() decorator. This is useful for data validation, logging, or specific route authentication.

import { DolphControllerHandler } from '@dolphjs/dolph/classes';
import { Dolph } from '@dolphjs/dolph/common';
import { Route, Post, DBody, DRes, UseMiddleware, DRequest } from '@dolphjs/dolph/decorators';
import { DRequest, DResponse, DNextFunc, SuccessResponse } from '@dolphjs/dolph/common';

// Example custom validation middleware
const validatePayload = (req: DRequest, res: DResponse, next: DNextFunc) => {
    if (!req.body.username) {
        return res.status(400).json({ error: 'Username is required' });
    }
    next();
};

@Route('users')
export class UserController extends DolphControllerHandler<Dolph> {
    @Post('create')
    @UseMiddleware(validatePayload) // Executed before the route handler
    async createUser(@DBody() body: any, @DRes() res: DRequest) {
        SuccessResponse({ res, message: 'User created successfully', data: { user: body } });
    }
}

Built-in Middlewares (Global)

DolphJS automatically provides and configures several global middlewares if they are enabled in your dolph_config.yaml:

CORS: Handles Cross-Origin Resource Sharing.
Helmet: Adds security headers.
JSON Parser: Parses incoming requests with JSON payloads (express.json()).
URL Encoded: Parses URL-encoded bodies (express.urlencoded()).

These middlewares run globally before the request ever reaches your Controller logic.

Chaining Middlewares

You can chain multiple middlewares on a single route by passing them as a sequence to @UseMiddleware(), or by using the decorator multiple times.

import { UseMiddleware, Post } from '@dolphjs/dolph/decorators';

@Post('upload')
@UseMiddleware(checkRateLimit)
@UseMiddleware(validateFileFormat)
async uploadFile() {
  // Logic executes only if both middlewares call next()
}