希望你能帮我。
我有一个名为 getEnergyFromPower 的函数,它返回一串值:
getEnergyFromPower(systemId: number, objectId?: string) {
...
return this.httpClient.get(this.BASE_URL + this.AGGREGATE_URL, {
headers: this.BEARER_OPTIONS.headers,
responseType: 'text',
params: params
})
}
另一个应该循环遍历 Observable 的值。 但是当我订阅和 console.log 它返回而不是像这样的观察数组:
organizeEnergy(systemId: number = 49439) {
return this.getSystemLayout(systemId).pipe(
map(res => {
return res.map(({object_id}) => this.getEnergyFromPower(49439, object_id))
})
)
}
this.optService.organizeEnergy().subscribe(res => console.log(res))
// Returns:
// [Observable, Observable, Observable, Observable, Observable, Observable, Observable, Observable]
我测试了 object_id 是否正确并返回正确的值,如下所示:
organizeEnergy(systemId: number = 49439) {
return this.getSystemLayout(systemId).pipe(
map(res => {
return res.map(({object_id}) => object_id)
})
)
}
this.optService.organizeEnergy().subscribe(res => console.log(res))
//RETURNS
// (8) [83978300, 83978301, 83978302, 83978303, 83978304, 83978305, 83978306, 83978307]
我也像这样对它进行了硬编码测试,它可以工作:
organizeEnergy(systemId: number = 49439) {
return this.getEnergyFromPower(systemId, '83978300')
}
this.optService.organizeEnergy().subscribe(res => console.log(res))
//RETURNS
// 2021/07/13 08:55:00.000,38
所以我猜我的问题是当我尝试在这一行中映射响应时:
organizeEnergy(systemId: number = 49439) {
...
return res.map(({object_id}) => this.getEnergyFromPower(49439, object_id))
...
}
所以我想循环遍历它并在我订阅它时动态地显示结果。
也许这是我还没有掌握的东西,因为我开始使用 Angular/Observables/HttpClient 已经两周了
答案 0 :(得分:3)
我认为您需要结合使用 switchMap
和 combineLatest
。
import { combineLatest } form 'rxjs';
import { switchMap } from 'rxjs/operators';
organizeEnergy(systemId: number = 49439) {
return this.getSystemLayout(systemId).pipe(
// change map to switchMap because we are going to switch to a new observable
switchMap(res => {
// combine all HTTP requests and return the results as an array
return combineLatest(...res.map(({object_id}) => this.getEnergyFromPower(49439, object_id)));
}),
)
}
// This should give you [2021/07/13 08:55:00.000,38, ...]
this.optService.organizeEnergy().subscribe(res => console.log(res))