DI & Decorators

NextRush provides a dependency injection system and decorator-based metadata for building structured, testable applications.

Package Overview

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Package	Purpose
@nextrush/di	Dependency injection container
@nextrush/decorators	Controller and route decorators

How They Work Together

The DI system and decorators are designed to work together:

@Service / @Repository — Mark classes for DI registration
@Controller — Mark classes as HTTP controllers
@Get / @Post — Define route handlers
@Body / @Param — Extract request data
Container — Resolve dependencies automatically

Quick Example

import { createApp, createRouter, listen } from 'nextrush';
import { controllersPlugin, Service, Controller, Get, Post, Body, Param } from 'nextrush/class';

// Service with DI
@Service()
class UserService {
  private users = [{ id: '1', name: 'Alice' }];

  findAll() {
    return this.users;
  }

  create(data: { name: string }) {
    const user = { id: Date.now().toString(), ...data };
    this.users.push(user);
    return user;
  }
}

// Controller with injected service
@Controller('/users')
class UserController {
  constructor(private userService: UserService) {}

  @Get()
  list() {
    return this.userService.findAll();
  }

  @Post()
  create(@Body() data: { name: string }) {
    return this.userService.create(data);
  }
}

// Bootstrap
const app = createApp();
const router = createRouter();
await app.plugin(
  controllersPlugin({
    router,
    root: './src',
    prefix: '/api',
  })
);
app.route('/', router);
await listen(app, 3000);

When to Use

Choose the paradigm that fits your application:

Building REST APIs with multiple endpoints - Need dependency injection for services - Want structured, testable code - Team prefers class-based patterns - Larger codebases with shared services

Building simple APIs - Prototyping - You want minimal moving parts - Prefer functional programming

Setup Requirements

Auto-Import with nextrush

The nextrush meta-package auto-imports reflect-metadata. If you use nextrush, no manual setup is needed beyond these tsconfig.json settings.

If using individual @nextrush/* packages, install reflect-metadata separately:

$ pnpm add reflect-metadata

// main.ts - FIRST LINE (only needed without the nextrush meta-package)
import 'reflect-metadata';

import { createApp } from '@nextrush/core';
// ... rest of imports

Enable decorators in tsconfig.json:

{
  "compilerOptions": {
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true
  }
}

Next Steps

@nextrush/di — Learn the DI container
@nextrush/decorators — Explore all decorators