HttpAdapterHost

Kind: Class

Source: packages/core/helpers/http-adapter-host.ts

Part of: Core

Defines the HttpAdapterHost object.

HttpAdapterHost wraps the underlying platform-specific HttpAdapter. The HttpAdapter is a wrapper around the underlying native HTTP server library (e.g., Express). The HttpAdapterHost object provides methods to get and set the underlying HttpAdapter.

HttpAdapterHost provides access to the platform-specific HttpAdapter used by the application, such as the Express or Fastify adapter. It acts as a shared integration point for framework features that need to inspect or interact with the underlying HTTP server without depending on a specific platform.

Diagram

mermaid
graph LR
  A[Nest Application] --> B[HttpAdapterHost]
  B --> C[HttpAdapter]
  C --> D[Express Adapter]
  C --> E[Fastify Adapter]
  D --> F[Native Express Server]
  E --> G[Native Fastify Server]

Usage

ts
import { Injectable } from '@nestjs/common';
import { HttpAdapterHost } from '@nestjs/core';

@Injectable()
export class ServerInfoService {
  constructor(
    private readonly adapterHost: HttpAdapterHost,
  ) {}

  getPlatform(): string {
    const httpAdapter = this.adapterHost.httpAdapter;

    return httpAdapter.getType(); // "express" or "fastify"
  }

  getHttpServer() {
    return this.adapterHost.httpAdapter.getHttpServer();
  }
}

AI Coding Instructions

• Inject HttpAdapterHost through Nest's dependency injection container instead of creating it manually in application services.
• Access the current platform adapter through the httpAdapter property; avoid casting directly to Express or Fastify unless platform-specific behavior is required.
• Use adapter abstraction methods such as getType() and getHttpServer() to keep integrations portable across supported HTTP platforms.
• Ensure the HTTP adapter has been initialized before relying on native server behavior, especially in bootstrap, testing, or lifecycle-sensitive code.