Method runMiddleware

packages/next/src/server/next-server.ts:1615–1789

* This method gets all middleware matchers and execute them when the request * matches. It will make sure that each middleware exists and is compiled and * ready to be invoked. The development server will decorate it to add warns * and errors with rich traces.

(params: {
    request: NodeNextRequest
    response: NodeNextResponse
    parsedUrl: ParsedUrl
    parsed: NextUrlWithParsedQuery
    onWarning?: (warning: Error) => void
  })

   * and errors with rich traces.
   */
  protected async runMiddleware(params: {
    request: NodeNextRequest
    response: NodeNextResponse
    parsedUrl: ParsedUrl
    parsed: NextUrlWithParsedQuery
    onWarning?: (warning: Error) => void
  }) {
    if (process.env.NEXT_MINIMAL) {
      throw new Error(
        'invariant: runMiddleware should not be called in minimal mode'
      )
    }

    // Middleware is skipped for on-demand revalidate requests
    if (
      checkIsOnDemandRevalidate(params.request, this.renderOpts.previewProps)
        .isOnDemandRevalidate
    ) {
      return {
        response: new Response(null, { headers: { 'x-middleware-next': '1' } }),
      } as FetchEventResult
    }

    let url: string

    if (this.nextConfig.skipProxyUrlNormalize) {
      url = getRequestMeta(params.request, 'initURL')!
    } else {
      // For middleware to "fetch" we must always provide an absolute URL
      const query = urlQueryToSearchParams(params.parsed.query).toString()
      const locale = getRequestMeta(params.request, 'locale')

      url = `${getRequestMeta(params.request, 'initProtocol')}://${
        this.fetchHostname || 'localhost'
      }:${this.port}${locale ? `/${locale}` : ''}${params.parsed.pathname}${
        query ? `?${query}` : ''
      }`
    }

    if (!url.startsWith('http')) {
      throw new Error(
        'To use middleware you must provide a `hostname` and `port` to the Next.js Server'
      )
    }

    const page: {
      name?: string
      params?: { [key: string]: string | string[] }
    } = {}

    const middleware = await this.getMiddleware()
    if (!middleware) {
      return { finished: false }
    }
    if (!(await this.hasMiddleware(middleware.page))) {
      return { finished: false }
    }