[英]Return Resolved Observable from Inside of a Promise
我正在嘗試通過擴展默認值來構建自定義Angular 2 http請求,並且我正在使用Ionic 2本地存儲來存儲身份驗證令牌。 (將來可能會使用文件系統)。 我的問題是如何從我的http服務返回已解析的promise,以便我可以在我的組件中訂閱Observable。 我試過Observable.fromPromise和其他變種無濟於事。
request(url: string|Request, options?: RequestOptionsArgs): Observable<Response> {
// Get the token used for this request.
// * Need to return this promise resolved.
var promise = this.storage.get('token').then(token => {
if (typeof url === 'string') { // meaning we have to add the token to the options, not in url
if (!options) {
// let's make option object
options = {headers: new Headers()};
}
options.headers.set('Authorization', 'Basic ' + token);
} else {
// we have to add the token to the url object
url.headers.set('Authorization', 'Basic ' + token);
}
return super.request(url, options).catch(this.catchAuthError(this));
}).catch(error => {
console.log(error);
});
}
Idea基於這篇博客文章,但Ionic存儲返回了一個承諾。 http://www.adonespitogo.com/articles/angular-2-extending-http-provider/
我不知道該存儲是否返回與Rx兼容的promise,但如果是,則解決方案應如下所示:
request(url: string|Request, options?: RequestOptionsArgs): Observable<Response> {
return Observable
.fromPromise(this.storage.get('token'))
.flatMap(token => {
if (typeof url === 'string') { // meaning we have to add the token to the options, not in url
if (!options) {
// let's make option object
options = {headers: new Headers()};
}
options.headers.set('Authorization', 'Basic ' + token);
} else {
// we have to add the token to the url object
url.headers.set('Authorization', 'Basic ' + token);
}
return super.request(url, options).catch(this.catchAuthError(this));
});
});
}
如果promise與observable不兼容,那么還有一種方法可以做到這一點,盡管它並不那么優雅:
request(url: string|Request, options?: RequestOptionsArgs): Observable<Response> {
return Observable.create((observer: Observer) => {
this.storage.get('token').then(token => {
if (typeof url === 'string') { // meaning we have to add the token to the options, not in url
if (!options) {
// let's make option object
options = {headers: new Headers()};
}
options.headers.set('Authorization', 'Basic ' + token);
} else {
// we have to add the token to the url object
url.headers.set('Authorization', 'Basic ' + token);
}
super.request(url, options).catch(this.catchAuthError(this)).subscribe(result => {
observer.next(result);
observer.complete();
});
}).catch(error => {
observer.error(error);
});
});
}
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