Unique Pipe Application Using RxJS Filters

Question

Unique Pipe Application Using RxJS Filters

I am facing an issue with subscribing to an observable using the async pipe in Angular. The data in the pipe may come from different sources and have varying structures based on the source.

The current implementation is not working as expected because I am overriding the initial value of this.data$, resulting in source A not being subscribed to.

Is there a way to 'split' the pipe based on a filter?

problem.component.ts:

// Data source A and logic A 
this.data$ = this.service.context.pipe(
  filter(context => context.flag === true),
  switchMap(context => this.dataSourceA(context.id)),
  map(data => this.processDataA(data))
);

// Data source B and logic B 
this.data$ = this.service.context.pipe(
  filter(context => context.flag === false),
  switchMap(context => this.dataSourceB(context.id)),
  map(data => this.processDataB(data))
);

problem.component.html

<pro-table [data]="data$ | async"></pro-table>

javascript angular typescript rxjs

Answer 1

Answer №1

Transfer the logic to your switchMap()

this.data$ = this.service.context.pipe(
   switchMap(context => context.flag
      ? this.dataSourceA(context.id).pipe(map(d => this.processDataA(d)))
      : this.dataSourceB(context.id).pipe(map(d => this.processDataB(d)))
   )
);

Answer 2

Transfer the logic to your switchMap()

this.data$ = this.service.context.pipe(
   switchMap(context => context.flag
      ? this.dataSourceA(context.id).pipe(map(d => this.processDataA(d)))
      : this.dataSourceB(context.id).pipe(map(d => this.processDataB(d)))
   )
);

Answer 3

Answer №2

Using a "higher order observable" is the key to achieving the desired result in a more effective way. Similar to a "higher order function" that can generate another function based on its arguments, a higher order observable can generate another Observable based on specific parametrization.

this.service.context.pipe(
  switchMap(context => context.flag ? this.dataSourceA(context.id).pipe(...) : this.dataSourceB(context.id).pipe(...))
);

Although it might seem complex at first, understanding higher order observables is crucial for optimizing your streams.

P.S. Remember: higher order observables allow you to parameterize your streams by working with streams of streams.

Answer 4

Using a "higher order observable" is the key to achieving the desired result in a more effective way. Similar to a "higher order function" that can generate another function based on its arguments, a higher order observable can generate another Observable based on specific parametrization.

this.service.context.pipe(
  switchMap(context => context.flag ? this.dataSourceA(context.id).pipe(...) : this.dataSourceB(context.id).pipe(...))
);

Although it might seem complex at first, understanding higher order observables is crucial for optimizing your streams.

P.S. Remember: higher order observables allow you to parameterize your streams by working with streams of streams.

Answer 5

Answer №3

If you want to consolidate multiple data sources and streamline your subscription process, consider implementing a Subject with the following approach:

    this.data$ = new Subject();
    observer = {
     next(data) { this.data$.next(data) },
     error(msg) { /*handle error*/ }
   };
    // Incorporating Data source A and its corresponding logic 
   this.service.context.pipe(
     filter(context => context.flag === true),
     switchMap(context => this.dataSourceA(context.id))
     map(data => this.processDataA(data))
   ).subscribe(observer);

   this.service.context.pipe(
     filter(context => context.flag === false),
     switchMap(context => this.dataSourceB(context.id))
     map(data => this.processDataB(data))
   ).subscribe(observer);

To optimize efficiency by utilizing the flag condition to maintain cohesion within one block of code:

this.service.context.pipe(
     switchMap(context => context.flag ?
         this.dataSourceA(context.id) : this.dataSourceB(context.id)
    )
     map(data => this.processData(data)) // effectively handle both scenarios
   ).subscribe(observer);

Answer 6

If you want to consolidate multiple data sources and streamline your subscription process, consider implementing a Subject with the following approach:

    this.data$ = new Subject();
    observer = {
     next(data) { this.data$.next(data) },
     error(msg) { /*handle error*/ }
   };
    // Incorporating Data source A and its corresponding logic 
   this.service.context.pipe(
     filter(context => context.flag === true),
     switchMap(context => this.dataSourceA(context.id))
     map(data => this.processDataA(data))
   ).subscribe(observer);

   this.service.context.pipe(
     filter(context => context.flag === false),
     switchMap(context => this.dataSourceB(context.id))
     map(data => this.processDataB(data))
   ).subscribe(observer);

To optimize efficiency by utilizing the flag condition to maintain cohesion within one block of code:

this.service.context.pipe(
     switchMap(context => context.flag ?
         this.dataSourceA(context.id) : this.dataSourceB(context.id)
    )
     map(data => this.processData(data)) // effectively handle both scenarios
   ).subscribe(observer);

Unique Pipe Application Using RxJS Filters

Answer №1

Answer №2

Answer №3

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