Middleware

Middleware is for registering middlewares to intercept and manipulate resources (request, response, ...) before handling route action.

By implementing IAbyssalMiddleware, we can easily create a middleware and apply it for Abyss.ts.

Create a middleware

To create a configuration, we will create a class that will implement interface IAbyssalMiddleware.

import { RequestContext, type MikroORM } from '@mikro-orm/core';

import type { AbyssalContext, IAbyssalMiddleware } from '@abyss.ts/core';

import { InjectOrm } from './decorators';

export class MikroOrmMiddleware implements IAbyssalMiddleware {
  constructor(@InjectOrm() private readonly orm: MikroORM) {}

  public use(
    _ctx: AbyssalContext<unknown>,
    next: (...args: TAny) => TAny,
  ): void {
    RequestContext.create(this.orm.em, next);
  }
}

A middleware has only one method use to receive AbyssalContext to intercept the request and next to move on to next middleware (if any).

NOTE

Always remember to call next or else you will be stuck at this step.

You can inject services from IoC to the constructor of the middleware. And use it in the use method.

NOTE

You can only inject services from all configurations that you already applied and from all middlewares that are registered before this middleware.

Apply global middleware

import { ExpressApplication } from '@abyss.ts/express-runner';
import { MikroOrmConfiguration, MikroOrmMiddleware } from '@abyss.ts/mikro-orm';

ExpressApplication.create()
  .useBodyParser()
  .usePort({
    port: 4_000,
    isStrict: true,
  })
  .useConfiguration(MikroOrmConfiguration)
  .useMiddleware(MikroOrmMiddleware)
  .run();

The middleware will be registered like a pipeline. That means the middlewares are applied from left to right.