Angular 2基于值刷新http请求

由于我对angular还不熟悉，我想知道实现我想要的目标的最佳实践是什么

我想请求一个API，直到我得到我想要的结果，请求之间的间隔

我使用两个嵌套服务（GiftsService和ApiService）：

gives.service.ts:

import { Injectable } from '@angular/core';
import { URLSearchParams } from '@angular/http';
import { environment } from '../../../environments/environment';
import { Observable } from 'rxjs/Rx';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';

import { ApiService } from './api.service';
import { Gift } from '../models';

@Injectable()
export class GiftsService {
  constructor (
    private apiService: ApiService
  ) {}

  get(id): Observable<Gift> {
    return this.apiService.get('/gifts/' + id)
           .map(data => data);
  }
  ...

更新

我是怎么做到的

this.giftsService.get(this.gift.id)
      .switchMap(data => data.status !== 'success' ? Observable.throw(new Error('status not successful')) : Observable.of(data))
      .retryWhen(attempts => {
        return Observable
        .range(1,10)
        .zip(attempts, function(i) {
          return(i);
        })
        .flatMap(function(i) {
          return Observable.timer(1000);
        })
      })
      .subscribe((
        data => {
          this.gift = data
        })
      );

---

您可以这样做：

this.giftsService.get（this.gift.id）
.switchMap（data=>data.status！==“OK”？Observable.throw（）：Observable.of（data））
.retryWhen（错误=>{/*此处设置重试逻辑*/}）
.subscribe（数据=>{}）

您可以将

retryWhen

操作符与

范围

和

计时器

结合使用

get(path: string, params = new URLSearchParams()) {
   return this.http.get(path, { 
       headers: this.setHeaders(), search: params 
   })
   .map(response => {
     response = response.json();
     if(response.status !== 'ok') {
       throw new Error('status not okay');
     }
     return response;
   })
   .retryWhen(errors => {
     return Observable
       .range(1, 3 /* maximum retry attempts */)
       .zip(errors)
       .flatMap([attempt, error] => {
         if(attempt >= 3) {
           return Observable.throw(error);
         }
         return Observable.timer(attempt*500 /* the retry timeout which increases after each attempt */);
       })
   })
   .catch(this.formatErrors)
}

---

在Error函数中，重试命中服务，例如this.giftsService.get（this.gift.id）.subscribe（数据=>{//if data.status！=“ok”重试，Error=>调用服务……=Error}），您可以使用rxjs retrywhen运算符，如下所示：

this.giftsService.get(this.gift.id)
      .switchMap(data => data.status !== 'success' ? Observable.throw(new Error('status not successful')) : Observable.of(data))
      .retryWhen(attempts => {
        return Observable
        .range(1,10)
        .zip(attempts, function(i) {
          return(i);
        })
        .flatMap(function(i) {
          return Observable.timer(1000);
        })
      })
      .subscribe((
        data => {
          this.gift = data
        })
      );

get(path: string, params = new URLSearchParams()) {
   return this.http.get(path, { 
       headers: this.setHeaders(), search: params 
   })
   .map(response => {
     response = response.json();
     if(response.status !== 'ok') {
       throw new Error('status not okay');
     }
     return response;
   })
   .retryWhen(errors => {
     return Observable
       .range(1, 3 /* maximum retry attempts */)
       .zip(errors)
       .flatMap([attempt, error] => {
         if(attempt >= 3) {
           return Observable.throw(error);
         }
         return Observable.timer(attempt*500 /* the retry timeout which increases after each attempt */);
       })
   })
   .catch(this.formatErrors)
}