角RxJS mergeMap类型

Question

尝试使用list.service请求URL将地理位置服务的经度和纬度提取到http.get中。

第一期：

“{}”类型上不存在企业属性“业务”

感谢你在这个问题上的帮助和时间

list.service.ts

import { Injectable } from '@angular/core';
import { Observable } from 'rxjs';
import { List } from '../models/list.model';
import { map } from 'rxjs/operators';
import { GeolocationService } from '../services/geolocation.service';
import { mergeMap } from 'rxjs/operators';
import { HttpClient } from '@angular/common/http';

@Injectable()
export class ListService {
    private serverApi = 'http://localhost:3000';

    constructor(private http: HttpClient, private geoServ: GeolocationService) { }

    public getAllLists(): Observable<List[]> {
        return this.geoServ.getGeoLocation().pipe(
          mergeMap<{businesses: List[]}>(({ latitude, longitude }) =>             
            this.http.get(`${this.serverApi}/yelp/${longitude}/${latitude}`).pipe(
            )
          ),
          map(res => res.businesses));
    }
}

geolocation.service.ts

import { Injectable } from '@angular/core';
import { Observable, Subject, asapScheduler, pipe, of, from, interval, merge, fromEvent, SubscriptionLike, PartialObserver } from 'rxjs';
@Injectable({
  providedIn: 'root'
})
export class GeolocationService {

  constructor() { }

  getGeoLocation() {
    return new Observable((observer) => {
      console.log('Geolocation working!');
      const options = {
        enableHighAccuracy: true,
        timeout: 5000,
        maximumAge: 0
      };
      const success = (pos) => {
        const crd = pos.coords;
        console.log(`Longitude : ${crd.longitude}`);
        const location = {
          "latitude" : crd.longitude,
          "longitude": crd.longitude
        };
        observer.next(location);
        observer.complete();
      };
      const error = (err) => {
        console.warn(`ERROR(${err.code}): ${err.message}`);
        observer.error(err);
        observer.complete();
      };
      navigator.geolocation.getCurrentPosition(success, error, options);
    });  
  }
}

list.model.ts

export interface List {
    id: string;
    name?: string;
    rating?: number;
    review_count?: number;
    url?: string;
    location: string;
    display_name?: string;
    image_url?: string;
    is_closed?: boolean;
}

添加了model.ts以帮助澄清

Answer 1

您的代码说GET返回一个List[]，但是数组不会有一个businesses属性，这就是为什么它在抱怨。您可以使用：

  public getAllLists(): Observable<List[]> {
    return this.geoServ.getGeoLocation().pipe(
      mergeMap(({ latitude, longitude }) =>
        this.http.get<any>(`${this.serverApi}/yelp/${longitude}/${latitude}`)
      ),
      map(res => res.businesses));
  }

这将编译，但如果响应确实是一个数组，则Observable可能最终会发出undefined。

Answer 2

似乎你还在使用旧的角质化http客户端。这对打字也不起作用。若要修复类型，请将类型对象添加到mergeMap泛型参数

public getAllLists(): Observable<List[]> {
  return this.geoServ.getGeoLocation().pipe(
    mergeMap<{latitude: string, longitude: string}, {businesses: List[]}>(({ latitude, longitude }) =>             
      this.http.get(`${this.serverApi}/yelp/${longitude}/${latitude}`).pipe(
        map(res => res.json()), // remove after updating to new http client
      )
    ),
    map(res => res.businesses));
}