我正在尝试使用多个http调用将数据存储在本地存储中.我使用forkJoin等待所有调用完成,然后我想恢复我的Promise.then调用链.我该怎么做呢？
updateCache() {
var cachesToUpdate;
return this.fetchServerTimestamps()
.then(res => {
var localTimestamps = this.getLocalTimestamps();
var serverTimestamps = this.getServerTimestamps();
//Compare timestamps and decide which cache data types to update
cachesToUpdate = this.cacheTypes.filter(function (cacheType) {
return localTimestamps ? localTimestamps[cacheType.timestamp] != serverTimestamps[cacheType.timestamp] : true;
});
}).then(res => {
//Request data and insert into cache
this.fetchData(cachesToUpdate)
.subscribe(res => {
res.forEach(function (item,index) {
this.insert(cachesToUpdate[index].messageType,JSON.stringify(item));
}.bind(this));
});
});
}
fetchData(cachesToUpdate): Observable<any> {
return forkJoin(cachesToUpdate.map(i => this.callservice.serverRead({ path: 'api/' + i.messageType })));
}
insert(key: string,value: string,compress = true) {
localStorage.setItem(key,compress ? LZString.compress(value) : value);
}
您可以使用Observable的toPromise()方法
https://github.com/Reactive-Extensions/RxJS/blob/master/doc/api/core/operators/topromise.md
this.fetchData(cachesToUpdate).toPromise().then(...)
编辑：作为FriOne& Lyubimov Roman在评论中提到,别忘了
import 'rxjs/add/operator/toPromise';
