JSON响应中的Angular 2过滤器

Question

I have problem filtering data from JSON response. I am using Google Geocoding API and get response where i want to retrtive only city name. The city name is stored in JSON response in one of the array, where types= "locality", "political"

How to retrive city name where types=["locality", "political"] ?

Here is my code:

geocoding.service.ts

 getLocation(lat: number, lon: number): Promise<any> {
    return this.http.get(this.apiUrl + lat + ',' + lon + '&key' + this.apiKey)
      .toPromise()
      .then((response) => Promise.resolve(response.json()));
  }

geocoding.ts

export class Geocoding {
    results: {
        address_components: {
            long_name: string;
            short_name: string;
        }
        formatted_address: string;
        types: {
            array: string;
            length: number;
        }
    }
    status: string;
}

weather.component.ts

import { Component, OnInit } from '@angular/core';
import { Observable } from 'rxjs/Observable';
import { GeocodingService } from '../data/google/geocoding/geocoding.service';
import { Geocoding } from '../data/google/geocoding/geocoding';

@Component({
  selector: 'app-weather',
  templateUrl: './weather.component.html',
  styleUrls: ['./weather.component.scss']
})

  location: Geocoding[];
  datasource: Geocoding[];
  sortedList: Geocoding[];

 ngOnInit() {
    this.findLocation2(52.406374, 16.9251681);
  }

 findLocation2(latitude: number, longtitude: number) {
    this.GeoService.getLocation(latitude, longtitude).then(data => {
      this.datasource = data;
      this.location = this.datasource;
      this.sortedList = this.location.filter(
        loc => loc.results.types.array === 'locality,political');
    });

When i run i get error:

EXCEPTION: Uncaught (in promise): TypeError: _this.location.filter is not a function

Answer 1

I found the solution! Both @Ramesh Rajendran and @Sebastian pointed me in the right directions:

 findLocation(latitude: number, longtitude: number) {
    return this.GeoService.getData(latitude, longtitude).subscribe(g => {
      this.geo = g;
      this.GEOARRAY = g.results;
      if (isArray(this.GEOARRAY)) {
        this.location = this.GEOARRAY.filter(x => x.types[0] === "locality" && x.types[1] === "political");
      }
    });
  }

I created GEOARRAY and pointed to g.results (which was array). Then i filtered what i wanted :) Thanks

Answer 2

this.location is should be an array. So you need to check if this.location is an array before you are doing filter .

findLocation2(latitude: number, longtitude: number) {
    this.GeoService.getLocation(latitude, longtitude).then(data => {
      this.datasource = data;
      this.location = this.datasource;
      if(Array.isArray(this.location)){
      this.sortedList = this.location.filter(
        loc => loc.results.types.array === 'locality,political');
    });
};