crud-service | basic ruby/sinatra CRUD service gem | DB Client library

I'm having a problem that ngFor isn't working in my app.

I splited my app into separate modules and included import { CommonModule } from '@angular/common'; into my child module and import { BrowserModule } from '@angular/platform-browser'; into my app.modules.ts file, but I still get the error following error.

I am pretty new to Ionic, Angular and Firebase and ran into a problem which I can't solve, even after I read all the threads about it and tried to apply them to my scenario.

Situation: I am building an Ionic4 (Angular) app which should list news articles from the web and is using Firebase's Firestore as a backend. Each article has a sender and a receiver, and I am successfully filtering for all one parameter to get only articles which have "me == receiver". On client side, in the app, I now want to filter additionally for the parameter whether an article is unread or read.

My goal is to do that with Ionic's segments (https://ionicframework.com/docs/api/segment).

I looked through many threats where some were recommending using pipes while others were saying it can be achieved easier. Any solution I tried to apply did not work yet.

My HTML "Tab2.html" is the following:

I have a few microservices, which are exposed through an API-Gateway. The gateway takes care of handling authentication and routing into the system. The services behind the gateway are mostly simple CRUD-Services. Each service exposes its own API and they communicate synchronously via HTTP. All of these services, including the API-Gateway, are "default" NestJS applications.

Let's stick with the Cats example. Whenever the Cat-Service updates or creates a new Cat, I want an CatCreatedEvent or CatUpdatedEvent to be emmited. The event should be pushed into some message broker like RabbitMQ and another service should listen to this event and process the event asynchronously.

I am not sure how to achive this, in terms of how to "inject" RabbitMQ the right way and I am wondering if this approach makes sense in generel. I have seen the CQRS Module for NestJS, but i think CQRS is a bit too much for this domain. Especially because there is no benefit in this domain to split read- and write-models. Maybe I am totally on the wrong track, so I hope you can give me some advises.