README.md

Module 09 - Http and rxMethod

Projects

colors-app	Demo of flatterners, http and rxMethod

Higher Order Observables

• We talked about Higher Order Observables - Observable<Observable<T>>
• We saw how to create higher order observable using the map operator along with a factory method.

const order1$ = interval(1000);
const order2$ = order1$.pipe(
    map(i => interval(1000))
);

/*
    order2$ is of type Observable<Observable<number>>
*/

• We understood why it's a bad practice to use subscribe inside subscribe, and therefore why it's important to "Flatten" the observable.
• We saw 4 types of flattening operators:
  • mergeAll, and mergeMap - Merges all nexts from all inner observables
  • switchAll, and switchMap - Subscribes always to the latest observable
  • concatAll and concatMap - Subscribes to the observables one after the other sequentially
  • exhaustAll and exhaustMap - Subscribes to observables until completion only when idle

Http

• We saw how to provide Http by using the provideHttpClient() function in app.congig
• We saw how to inject HttpClient to services
• We understood that the http client works with Cold Observables
• We saw how to call the get<T> function to fetch data from the web
• We saw that using the proper flattening operator, we can also cancel requests that are no longer relevant

rxMethod

• We understood what rxMethod is - we understood that it is a method that accepts 3 types of input
  • T
  • Observable
  • Signal
• We understood that it accepts a method as parameter
• We understood that the method accepts an observable and should respond to it using operators
• We saw that we can use rxMethod for integration between signal store and reactive services (asyncronous services)
• We saw how to connect http with signal store