@xfeature/nestjs

A NestJS integration for @xfeature/core that provides decorators for feature-flagging controllers and modules.

Installation

bun add @xfeature/nestjs

Quick Start

1. Define your features

import { defineFeature, registerFeatures } from '@xfeature/core';

export const Features = registerFeatures({
  UserManagement: defineFeature('user-management', {
    Registration: defineFeature('registration'),
    Profile: defineFeature('profile')
  }),
  Analytics: defineFeature('analytics')
});

2. Use features in your NestJS application

import { Controller } from '@nestjs/common';
import { FeatureController } from '@xfeature/nestjs';
import { Features } from './features';

@FeatureController(Features.UserManagement)
export class UserController {
  @Get()
  getUsers() {
    // This controller is only accessible when user-management feature is enabled
    return this.userService.getUsers();
  }
}

@FeatureController(Features.UserManagement.Registration)
export class RegistrationController {
  @Post()
  register(@Body() userData: any) {
    // This controller is only accessible when user-management.registration feature is enabled
    return this.userService.register(userData);
  }
}

3. Feature-flag entire modules

import { Module } from '@nestjs/common';
import { FeatureModule } from '@xfeature/nestjs';
import { Features } from './features';

@FeatureModule(Features.Analytics)
export class AnalyticsModule {
  // This module is only loaded when analytics feature is enabled
}

API Reference

@FeatureController(feature, options?)

Decorator that conditionally applies @Controller() based on feature flag state.

@FeatureController(Features.UserManagement)
export class UserController {
  // Controller is only registered when user-management feature is enabled
}

@FeatureModule(feature, options?)

Decorator that conditionally applies @Module() based on feature flag state.

@FeatureModule(Features.Analytics)
export class AnalyticsModule {
  // Module is only registered when analytics feature is enabled
}

Best Practices

1. Organize Features Hierarchically: Use nested features to group related functionality

   const Features = {
     Ecommerce: defineFeature('ecommerce', {
       Cart: defineFeature('cart'),
       Payment: defineFeature('payment')
     })
   };

2. Use Environment Variables: Features are automatically loaded from environment variables

   # Enable specific features
   FEATURES="user-management,analytics,user-management.registration"

3. Feature Naming: Use kebab-case for feature names to ensure consistency

   defineFeature('user-management') // ✅ Good
   defineFeature('userManagement') // ❌ Avoid

License

This project is licensed under the MIT License - see the LICENSE file for details.