Is there a more elegant way of doing the following?
private getHeaders(): Observable<any> {
let version;
let token;
return this.appInfo.getVersion()
.pipe(
tap(appVersion => version = appVersion),
mergeMap(() => this.storage.get('access_token')),
tap(accessToken => token = accessToken),
mergeMap(accessToken => of(this.createHeaders(version, token)))
);
}
How can I more fluently remember the two return values of this.appInfo.getVersion()
and this.storage.get('access_token')
without writing them to temporary variables with the power of rxjs?
Perhaps merging some observables into one? There are so many rxjs operators and stuff...
Using forkJoin
:
.pipe(
mergeMap((appVersion) => forkJoin(
of(appVersion),
this.storage.get('access_token').take(1)
)),
mergeMap(([version, token]) => {
this.createHeaders(version, token)
})
)
But even easier with withLatestFrom
:
.pipe(
withLatestFrom(this.storage.get('access_token')),
mergeMap(([version, token]) => {
this.createHeaders(version, token)
})
)
I have included both because withLatestFrom
is easier but forkJoin
should be used where you need to access the initial parameter. For example, if you were doing this.storage.get(appVersion)
You may want to try something like this
private getHeaders(): Observable<any> {
return this.appInfo.getVersion()
.pipe(
mergeMap(version => this.storage.get('access_token')
.map(token => ({version, token})),
map(data => this.createHeaders(data.version, data.token))
);
}
ALTERNATIVE VERSION WITH ZIP
private getHeaders(): Observable<any> {
const versionObs = this.appInfo.getVersion();
const tokenObs = this.storage.get('access_token');
return Observable.zip(versionObs, tokenObs)
.pipe(
map(data => this.createHeaders(data[0], data[1]))
);
}
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