http.get被两次调用 [英] http.get being called twice

问题描述

我有这个http.get请求，但是它被触发了两次.它在我的构造函数中.

I have this http.get request but it is being triggered twice. It is within my constructor.

import { Component } from '@angular/core';
import { NavController, LoadingController } from 'ionic-angular';
import { Auth, User, IDetailedError } from '@ionic/cloud-angular';
import { Http, URLSearchParams, Headers } from "@angular/http"
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/share';

import { DetailsPage } from '../details/details';
import { LoginPage } from '../login/login';

@Component({
  selector: 'page-dashboard',
  templateUrl: 'dashboard.html'
})
export class Dashboard {

  visitors: any;
  currentSite: any;
  searchDate: String = new Date().toISOString();

  constructor(public navCtrl: NavController, public http: Http, public loadingCtrl: LoadingController, public user: User, public auth: Auth) {

    if (this.auth.isAuthenticated()) {

        this.currentSite = this.user.get('siteName',0);

        let loading = this.loadingCtrl.create({
          spinner: 'bubbles',
          content: 'Fetching visitors ...',
          duration: 5000
        });

        loading.present();  

        var headers = new Headers();
        headers.append('Content-Type', 'application/x-www-form-urlencoded');  
        headers.append('Authorization', 'Basic '+ btoa(this.user.get('siteID',0)+':'+this.user.get('token',0)));      

        this.http.get('http://api.domain.com/visitors?search_from='+this.searchDate+'&search_to='+this.searchDate, {headers:headers}).map(res => res.json()).share().subscribe(data => {
            this.visitors = data.res;
            loading.dismiss();
        });   

    } else {
        this.navCtrl.setRoot(LoginPage);
    }

  }

基于 Angular2 http.post被执行两次需要包括share()，但是当我尝试这个时，我得到一个错误..

Based on Angular2 http.post gets executed twice it looks like I need to include share() but when I try this I get an error ..

如果将share()放在末尾，则会显示订阅类型上不存在该属性"，如果在订阅前放置该属性，则会得到可观察类型上不存在属性共享"

If I put share() at the end then I get "Property does not exist on type Subscription" and if I put it before subscribe then I get "Property share does not exist on type observable"

有人可以告诉我share()应该去哪里……或者我实际上是否有其他问题?

Can somebody tell me where share() should go ... or whether I actually have a different issue?

推荐答案

您提到了OPTIONS请求.您是否正在从与API不同的服务器上运行angular 2网站?

You mentioned the OPTIONS request. Are you running the angular 2 site from a different server than your API?

如果是这样，则您必须处理CORS-即浏览器将发送第一个OPTIONS请求，并检查响应的标头以查看是否允许CORS.

If so, then you'll have to deal with CORS - i.e. the browser will send a first OPTIONS request and check the headers of the response to see if CORS is permitted.

这将解释为什么您在后端API上看到两个请求

That would explain why you see two requests on your back end API

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