角2/5.使用HttpClient的服务会出错并且无法正常工作 [英] Angular 2/5. Service with HttpClient makes mistake and doesn't works

问题描述

我正在尝试提供从远程服务器获取(试图获取)XML文件的服务.我没有足够的经验来独自发现错误. app.component.ts的相关代码:

I'm trying to make service which takes (trying to take) XML-file from remote server. I haven't enough experience to find mistakes by myself. Relevant code of app.component.ts:

import { Component, OnInit, AfterViewInit, ElementRef, ViewChild, Renderer2 } from '@angular/core';
import { CanvasSettings } from './canvas-settings';
import { Rate } from './rate';
import { RateService } from './rates.service';
import { CBRRateService } from './cbrrates.service';
import { DatePoints, Year, Month, Day, Monthes, ofMonth } from './dates';
import { HttpClient, HttpHandler, HttpClientModule } from '@angular/common/http';

@Component({ // line 9, there is an error
    selector: 'app-root',
    templateUrl: './app.component.html',
    styleUrls: ['./app.component.css'],
    providers: [ RateService, CBRRateService, HttpClient, HttpHandler, HttpClientModule ]
})

export class AppComponent implements OnInit, AfterViewInit {

    @ViewChild("helper") helper: ElementRef;

    //...
    rates: Rate[];
    cbrrates: any;
    //...

    constructor(private _rateService: RateService, private _rateCBRService: CBRRateService) {}

    ngOnInit() {

        //...

    }

    getCBRRates():void { // Uses http. Doesn't work.

        this._rateCBRService.getCBRRates().subscribe(cbrrates => {this.cbrrates = cbrrates});

    }
    getRates():void { // Doesn't use http, works fine

        this._rateService.getRates().subscribe(rates => this.rates = rates);

    }

    //...

}

和cbrrates.service.ts的代码清单:

import { Injectable } from '@angular/core';
import { Observable } from 'rxjs/Observable';
import { HttpClient, HttpHandler, HttpClientModule, HttpHeaders } from '@angular/common/http';
import { of } from 'rxjs/observable/of'; // It used in earlier version, now it useless

const httpOptions = {
    headers: new HttpHeaders({ 'Content-Type': 'plain/text' }) // I've found no way to get XML, so 'plain/text'. Everywhere JSON.
};

@Injectable()
export class CBRRateService {

    targetURL: string = "http://www.cbr.ru/scripts/XML_dynamic.asp?date_req1=01/01/2016&date_req2=02/02/2018&VAL_NM_RQ=R01235";

    constructor(private http: HttpClient){}

    getCBRRates(): Observable<any> {
        return (this.http.get(this.targetURL, {responseType: 'text'}));
    }

}

bash控制台中的错误:

Error in bash console:

 ERROR in src/app/app.component.ts(9,12): error TS2345:
 Argument of type '{ selector: string; templateUrl: string;
 styleUrls: string[]; providers: (typeof HttpHandler | ty...' is not
 assignable to parameter of type 'Component'.

   Types of property 'providers' are incompatible.

     Type '(typeof HttpHandler | typeof HttpClient | typeof HttpClientModule
 | typeof CBRRateService)[]' is not assignable to type 'Provider[]'.

       Type 'typeof HttpHandler | typeof HttpClient | typeof HttpClientModule
 | typeof CBRRateService' is not assignable to type 'Provider'.

         Type 'typeof HttpHandler' is not assignable to type 'Provider'.

           Type 'typeof HttpHandler' is not assignable to type 'ClassProvider'.

             Property 'provide' is missing in type 'typeof HttpHandler'.

浏览器控制台中的错误:

Error in browser console:

Failed to load resource: the server responded with a status of 404 (Not Found)

总共2个问题:

1. 如何修复服务CBRRateService并使其正常工作?

是否存在通过服务从远程服务器获取数据的方式获取和解析XML数据的方法?

Does exist some way to get and parse XML-data via service which gets data from remote server?

推荐答案

@MikhailFilchushkin，当您编写this.http.get(this.targetURL，{responseType:'text'})时，您会在响应中收到字符串" ".因此，您必须将此字符串转换为对象.您可以做类似的事情

@MikhailFilchushkin, when you write this.http.get(this.targetURL, {responseType: 'text'}), you recibe in the response a "string". So, you must convert this string to an object. You can do something like

getCBRRates(): Observable<any> {
    return this.httpClient.get(this.targetURL, { responseType: 'text' })
      .map((response: string) => { //response is a string
        let result: any[] = [];
        let records = response.split('<Record'); //make a array of string
        let index = 0;
        records.forEach(r => {
          let date = r.split('Date=');
          let id = r.split('Id=');
          let nominal = r.split('<Nominal>');
          let value = r.split('<Value>');
          if (index > 0) { //the first is the header of the xml
            result.push({
              date: date[1].substr(1,10), //date[0] is the text before "Date"
              id: id[1].substr(1,6), //idem id
              nominal: nominal[1].substring(0,nominal[1].indexOf('<')),
              value: value[1].substring(0,value[1].indexOf('<')),
            })
          }
          index++;

        });
        return result;
      });
  }

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