Efficiently maintain a set of objects with 'CRUD-Observables' - rxjs

Question

I've been experimenting with feathersjs and angular2/Rx.
What I'm trying to achieve is building an angular2 service that's wrapping a feathersjs service in such a way that one can just subscribe to an Observable that emits an up-to-date set of items after any kind of CRUD.
It basically works. However, I don't find the way it's done very elegant:
Wrapping and unwrapping every object that's coming in doesn't seem efficient. Am I taking 'Everything's a stream' too far?
getService(){
let data$: Observable<any> = Observable.from([initialSetOfItems]);
let created$: Observable<any> = Observable.fromEvent(feathersService, 'created').map(o => {return {action: 'c', data: o}});
let updated$: Observable<any> = Observable.fromEvent(feathersService, 'updated').map(o => {return {action: 'u', data: o}});
let removed$: Observable<any> = Observable.fromEvent(feathersService, 'removed').map(o => {return {action: 'r', data: o}});
return data$
.merge(created$, updated$, removed$)
.scan((arr: any[], newObj) => {
switch (newObj.action){
case 'c':
return [].concat(arr, newObj.data);
case 'u':
let indexToUpdate = arr.findIndex((element) => (element.id === newObj.data.id));
if (indexToUpdate > -1){
arr[indexToUpdate] = newObj.data;
}
return arr;
case 'r':
return arr.filter(element => (element.id != newObj.data.id))
}
});
}
I know this might be opinionated. Please bear with me. Rx is a little hard to wrap your head around.
How would you guys try to achieve this?

Answer 1

I think what you are looking for is exactly what feathers-reactive is supposed to do. It is a plugin that turns any service method into an RxJS observable that automatically updates on real-time events. It can be used like this:
const feathers = require('feathers');
const memory = require('feathers-memory');
const rx = require('feathers-reactive');
const RxJS = require('rxjs');
const app = feathers()
.configure(rx(RxJS))
.use('/messages', memory());
const messages = app.service('messages');
messages.create({
text: 'A test message'
}).then(() => {
// Get a specific message with id 0. Emit the message data once it resolves
// and every time it changes e.g. through an updated or patched event
messages.get(0).subscribe(message => console.log('My message', message));
// Find all messages and emit a new list every time anything changes
messages.find().subscribe(messages => console.log('Message list', messages));
setTimeout(() => {
messages.create({ text: 'Another message' }).then(() =>
setTimeout(() => messages.patch(0, { text: 'Updated message' }), 1000)
);
}, 1000);
});
If you want to give it a try, we would love to get some feedback (and bug reports).