Hi Seagu,
I have in most off my apps something like this:
import { Injectable } from '@angular/core';
import { Observable, ReplaySubject } from 'rxjs';
import { filter, pluck, share } from 'rxjs/operators';
/** available types. */
export enum MsgBusType {
/** use for generic/one-off messages */
Generic = 'generic',
/** use for changes in auth status */
Auth = 'auth',
/** use for plugins */
Plugins = 'plugins'
}
/** describes a message */
export interface MsgBusMessage {
/** type as defined in above enum */
type: MsgBusType;
/** subtype, can be used to diversify in a certain module */
subType?: string;
/** payload, usually json-like data */
payload: any;
}
/**
* Messagebus service
*/
@Injectable({
providedIn: 'root'
})
export class MsgBusSerrvice {
/** internal subject to push out msg, holds on to the last one */
private messages = new ReplaySubject<MsgBusMessage>(1);
/**
* internal observable, that makes sharing the msg easier.
* (note, it doesn't replay!)
*/
private messages$ = this.messages.pipe(share());
/**
* sends out a message into the bus
*/
emit = (m: MsgBusMessage) => {
this.messages.next(m);
};
/**
* Return a function that can emit messages of a set Type.
* this makes it easier if you have the need to repeated msgs.
* sample:
* ```
* const authUpdate =
MsgBusService.createEmitter<AuthMessage>(MsgBusType.auth)
* authUpdate({user, ttl})
* ```
*/
createEmitter = <T>(type: MsgBusType, subType?: string) => (
payload: T
) => this.emit({ type, payload, subType });
/**
* !! FOR DEBUGGING ONLY !!
* generic listener observable for __ALL__ messages that pass.
* normally you use a filteredObservable
*/
ListenForAllMessages = (): Observable<MsgBusMessage> => {
return this.messages$;
};
/**
* returns an observable that only fires on its given MsgBusType, and
subfilter.
* it only emits the payload, not the complete message.
* you can put in a type for the payload like this:
* `const authEvents$ = filteredObservable<AuthMessage>(MsgBusType.auth)`
*/
filteredObservable = <T>(filterOn: MsgBusType, subTypeToFilter?: string):
Observable<T> => {
return this.messages$.pipe(
filter(
m => m.type === filterOn && (subTypeToFilter === undefined || m.subType ===
subTypeToFilter)
),
pluck('payload')
// tap<T>(pl => console.log('msg', type, subType, pl))
);
};
}
Regards
Sander
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