Conditionally execute the switchMap, otherwise, cancel all without firing the error event

1

Conditionally execute/enter the switchMap if the confirmation result is isConfirmed: true.

Try filter. E.g:

from(isConfirmed).pipe(
  filter((res) => !!res.isConfirmed)
  ...
)

This will only emit values that match the filter condition.

2

Where is the perfect location to add the tap or finalize...?

• finalize: At the end, so if any subscription fails before it, it is executed.

• tap: Wherever you want something to be executed. For example, if you wanted to print users o emails you'd need to put the tap instruction in the part of the pipe where you have that data.

Summarizing:

from(isConfirmed).pipe(
  filter((res) => !!res.isConfirmed),
  switchMap((res) => from(this.service.httpCallOneGetUsers())),
  map((users) => users.map((user) => user.email)),
  switchMap((emails) =>
    this.service.httpCallTwoSendMessage(title, message, emails)
  ),
  finalize(() => this.loadingService.dismiss()),
  tap({
    next: () => console.log("Message sent!"),
    error: () => console.log("Could not send the message."),
  })
);

Note: the last tap acts like the receiver of the subscription result, thats why it is last. But that code should go in the subscribe.

UPDATE (from comments)

To finalize the observable when the condition is not met you should do something like this:

from(isConfirmed).pipe(
  switchMap((res) => {
    if (res.isConfirmed) {
      this.loadingService.present();
      return from(this.service.httpCallOneGetUsers());
    } else {
      throwError("");
    }
  }),
  map((users) => users.map((user) => user.email)),
  switchMap((emails) =>
    this.service.httpCallTwoSendMessage(title, message, emails)
  ),
  finalize(() => this.loadingService.dismiss()),
  tap({
    next: () => console.log("Message sent!"),
    error: () => console.log("Could not send the message."),
  })
);

If the condition is true, the pipe will execute in order as expected. If the condition is false, from the first switchMap it will jump to finalize.