MiddlewareBase classes

MiddlewareBase extends FlareBase and mirrors controller composition. Register with host.http.use(Cls) or g.use(Cls) inside a group. At host.build(), the class must implement at least one of before(), after(), or finally().

import {
  MiddlewareBase,
  FlareHost,
  flareState,
  Logger,
} from "@flare-ts/core";
import { node } from "@flare-ts/core/node";

const AuthUser = flareState<{ id: string }>("AuthUser");

class AuthMiddleware extends MiddlewareBase {
  public static override deps = [Logger];
  public static override state = [];
  public static override provides = [AuthUser];

  before() {
    const token = this.ctx.req.headers.get("authorization");
    if (!token) return this.unauthorized({ error: "missing token" });
    this.ctx.state.set(AuthUser, { id: "u1" });
  }

  finally() {
    this.inject(Logger).info("request done", {
      user: this.ctx.state.get(AuthUser)?.id ?? null,
    });
  }
}

const host = new FlareHost(node);
host.http.use(AuthMiddleware);

host.http.get("/me", { state: [AuthUser] }, (ctx) => {
  return { id: ctx.state.require(AuthUser).id };
});

const app = host.build();
app.run();

Required static members

Member	Required?	Purpose
static deps	Yes	Services this middleware may inject() ([] if none)
static state	Yes	State tokens this middleware reads ([] if none)
static provides	Optional	State tokens written in before()
static config	Optional	Config tokens this middleware may read

Registration throws at call time if deps or state is missing. Missing lifecycle hooks throw at host.build().

Instance API

Member	Description
this.ctx	FlareHttpContext for the current request
this.inject(token)	Resolve a service from static deps
this.config(token)	Resolve a config token from static config

Optional lifecycle methods:

Method	Signature
before()	MiddlewareOverride | Promise<MiddlewareOverride>
after(result)	MiddlewareOverride | Promise<MiddlewareOverride>
finally(result)	MiddlewareOverride | Promise<MiddlewareOverride>

Response helpers

Protected helpers on MiddlewareBase for short-circuiting from before():

Method	Status
badRequest(body)	400
unauthorized(body)	401
forbidden(body)	403
notFound(body)	404
tooManyRequests(body)	429
error(body)	500

Read request data from this.ctx.req. There is no this.req.

Related

• Inline middleware
• Middleware that provides state: auth pattern walkthrough
• Middleware overview: group exclude and replace