MiddlewareBuilder

Kind: Class

Source: packages/core/middleware/builder.ts

Part of: Core

MiddlewareBuilder collects middleware registrations and converts them into normalized MiddlewareConfiguration entries for the framework’s middleware pipeline. It exposes a fluent apply() API through MiddlewareConfigProxy, while build() returns the accumulated configurations and getHttpAdapter() provides access to the underlying HTTP server adapter.

Implements: MiddlewareConsumer

Methods

Where it refuses work

• MiddlewareBuilder stops the work with an early return when route.method !== item.method.

Diagram

mermaid
graph LR
  A[Application Module] --> B[MiddlewareBuilder]
  B -->|apply(...middleware)| C[MiddlewareConfigProxy]
  C -->|forRoutes / exclude| D[MiddlewareConfiguration]
  B -->|build()| E[MiddlewareConfiguration[]]
  B -->|getHttpAdapter()| F[HttpServer]
  E --> G[Middleware Pipeline]
  F --> G

Usage

ts
import { MiddlewareBuilder } from '@nestjs/core/middleware/builder';
import { RoutesMapper } from '@nestjs/core/middleware/routes-mapper';

// Typically created and used internally by the framework.
const builder = new MiddlewareBuilder(
  new RoutesMapper(container, applicationConfig),
  httpAdapter,
);

builder
  .apply(LoggerMiddleware, AuthenticationMiddleware)
  .exclude('health')
  .forRoutes('users');

const middlewareConfigurations = builder.build();

// The HTTP adapter used to register middleware with the server.
const adapter = builder.getHttpAdapter();

AI Coding Instructions

• Use apply() as the entry point for registering one or more middleware classes/functions; route selection is configured through the returned MiddlewareConfigProxy.
• Call build() only after all middleware registrations are complete, since it returns the builder’s accumulated configuration list.
• Preserve middleware ordering: configurations are processed in registration order, so avoid rearranging stored entries without considering execution order.
• Use getHttpAdapter() when integration code needs server-specific middleware behavior; avoid coupling configuration-building logic directly to a specific HTTP platform.
• Keep route mapping and exclusion logic delegated to MiddlewareConfigProxy and route-mapping utilities rather than duplicating route normalization in the builder.

Relationships

• IMPORTS → HttpServer
• IMPORTS → MiddlewareConsumer
• IMPORTS → Type
• IMPORTS → MiddlewareConfigProxy
• IMPORTS → MiddlewareConfiguration
• IMPORTS → RouteInfo
• IMPORTS → stripEndSlash