How to extract JSON Data and load into an Array in Angular 7

Question

I have a local JSON File with some data. I want to extract only the CityCodes from it and store in an Array. Then i want to send the CityCodes to the OpenWeatherMap API Request. Finally want to Display all the Weather Records in the HTML file.

CityData.json :

{
    "List": [
    {
    "CityCode": "1248991",
    "CityName": "Colombo",
    "Temp": "33.0",
    "Status": "Clouds"
    },
    {
    "CityCode": "1850147",
    "CityName": "Tokyo",
    "Temp": "8.6",
    "Status": "Clear"
    },
    {
    "CityCode": "2644210",
    "CityName": "Liverpool",
    "Temp": "16.5",
    "Status": "Rain"
    }
]

Weather.Service.ts :

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { map } from 'rxjs/operators';

@Injectable({
  providedIn: 'root'
})
export class WeatherService {

  apiKey = '9402da6bd74c395f71604c624cc2b231';
  url;

  constructor(private http:HttpClient) { 
    this.url='http://api.openweathermap.org/data/2.5/group?id=';  //API GET URL

  }

  getWeather(cityCode){
    return this.http.get(this.url+cityCode+'&units=metric&appid='+this.apiKey);
  }

}

home.component.ts :

here i am passing the area code manually. Instead of that i need to send the area codes form JSON here.

import { Component, OnInit } from '@angular/core';
import { WeatherService } from "../shared/weather.service";
// import { weather} from "../shared/weather.model";

@Component({
  selector: 'app-home',
  templateUrl: './home.component.html',
  styleUrls: ['./home.component.css']
})
export class HomeComponent implements OnInit {

  location={    
    code: '1248991'  //Passing Area Code Manually
  };

  public weather: any;

  constructor(private weatherService:WeatherService) {

  }

  ngOnInit() {
    this.weatherService.getWeather(this.location.code).subscribe((Response:any)=>{
      console.log(Response);
      this.weather = Response.list;
    })
  }

}

home.component.html :

<table class="table table-hover">
          <thead>
            <th>City</th>
            <th>City Code</th>
            <th>Temperature</th>
            <th>Description</th>            
          </thead>
          <tbody>
            <tr *ngFor="let weather of weather">
              <td>{{weather.name}}</td>
              <td>{{weather.id}}</td>
              <td>{{weather.main.temp}}</td>
              <td>{{weather.weather[0].description}}</td>              
            </tr>
          </tbody>
        </table>

Ahamed Safnaj · Accepted Answer · 2019-06-29 10:44:37Z

I Solved it by pushing the JSON Response into an Array.

Home.component.ts

  public data: any;
  public weather: any;

  constructor(private weatherService:WeatherService) {

  }

  ngOnInit() {   
    this.weatherService.getJsonData('./assets/City.json').subscribe(data => {
            this.data = data;         //Reading JSON Data
            this.getWeatherList();    //Calling GetWeatherList Function
      }); 
  }

  getWeatherList(){
    if (this.data) {

      // console.log(this.data);

      const dataList = this.data.List;
      let tempArr : any = [];

      for (let temp of dataList) {
        this.weatherService.getWeather(temp.CityCode).subscribe((Response: any) => {
          tempArr.push(Response.list[0]);         //Pushing Response to Array
        })        
      }
      console.log(tempArr)
      this.weather = tempArr;   //Assigning Array to Weather Constant
    }
  }

Rahul Sharma · Accepted Answer · 2019-04-08 18:34:28Z

read JSON first using HTTP get and use forJoin to read parallel(like Promise.all) weather data from API.

// add in service
get(url){
    return this.http.get(url);
}

//component
ngOnInit() {
    this.weatherService.get('json file url').subscribe((cities:any)=>{
        const {List} = cities;
        const obsArr = List.map(location => this.weatherService.getWeather(location.CityCode))
        forkJoin(obsArr).subscribe(  => { // import forkJoin
            console.log(val)
            this.weatherlist = val; // modify according to response
        }); 
    })
  }

//html
<tr *ngFor="let weather of weatherlist">
    <td>{{weather.name}}</td>
    <td>{{weather.id}}</td>
    <td>{{weather.main.temp}}</td>
    <td>{{weather.description}}</td>              
</tr>

imanshu15 · Accepted Answer · 2019-04-08 19:32:15Z

1

Update the weather service to take the local JSON file path and read the content,

  public getJsonData(filePath: string){
        return this.http.get(filePath);
  }

In you component do the following,

  export class HomeComponent implements OnInit {

  public data: any;
  public weather: any;

  constructor(private weatherService: WeatherService) {}

  ngOnInit() {   
    this.weatherServiceget.getJsonData(./data.json).subscribe(data => {
            this.data = data;
            this.getWeatherList();
      }); 
  }

  getWeatherList(){
    if (this.data) {
      const dataList = JSON.parse(this.data).List;
      for (let temp of dataList) {
        this.weatherService.getWeather(temp.CityCode).subscribe((Response: any) => {
          console.log(Response);
          if (Response && Response.list) {
            this.weather.push(Response.list[0]);
          }
        })
      }
    }
  }
}

here is a working example, cannot read file data on stackblitz so its hardcoded. Example

edited Apr 8, 2019 at 19:32

answered Apr 8, 2019 at 19:06

imanshu15

7644 silver badges24 bronze badges

6 Comments

imanshu15 Over a year ago

well './' start from where your component is, if you have to go back then '../shared' like the you have to figure out your path

Ahamed Safnaj Over a year ago

Not Working..! Should I call getWeatherList() Method inside ngOnInit() ??

imanshu15 Over a year ago

ah sorry, my bad. YES! call getWeatherList after you got data from json file. I updated the code as well

Ahamed Safnaj Over a year ago

I Couldnt call the JSON File. Do i need to import it ?? its in a assets folder.

Ahamed Safnaj Over a year ago

Getting This Error "Unexpected token o in JSON at position 1"

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