enter image description hereI'm trying to build a weather forecast app and trying to iterate over temperature. I can't seem to figure out how I can only get data for temperature.
{
"cod": "200",
"message": 0,
"cnt": 40,
"list": [
{
"dt": 1641049200,
"main": {
"temp": 14.33,
"feels_like": 13.88,
"temp_min": 13.46,
"temp_max": 14.33,
"pressure": 1017,
"sea_level": 1017,
"grnd_level": 1013,
"humidity": 79,
"temp_kf": 0.87
},
"weather": [
{
"id": 804,
"main": "Clouds",
"description": "overcast clouds",
"icon": "04d"
}
],
"clouds": {
"all": 100
},
"wind": {
"speed": 5.51,
"deg": 212,
"gust": 13.66
},
"visibility": 10000,
"pop": 0.2,
"sys": {
"pod": "d"
},
"dt_txt": "2022-01-01 15:00:00"
},
{
"dt": 1641060000,
"main": {
"temp": 13.68,
"feels_like": 13.27,
"temp_min": 12.37,
"temp_max": 13.68,
"pressure": 1017,
"sea_level": 1017,
"grnd_level": 1013,
"humidity": 83,
"temp_kf": 1.31
},
"weather": [
{
"id": 804,
"main": "Clouds",
"description": "overcast clouds",
"icon": "04n"
}
],
"clouds": {
"all": 100
},
"wind": {
"speed": 5.06,
"deg": 223,
"gust": 13.39
},
"visibility": 10000,
"pop": 0.06,
"sys": {
"pod": "n"
},
"dt_txt": "2022-01-01 18:00:00"
},
{
"dt": 1641276000,
"main": {
"temp": 5.55,
"feels_like": 0.95,
"temp_min": 5.55,
"temp_max": 5.55,
"pressure": 995,
"sea_level": 995,
"grnd_level": 992,
"humidity": 91,
"temp_kf": 0
},
"weather": [
{
"id": 501,
"main": "Rain",
"description": "moderate rain",
"icon": "10n"
}
],
"clouds": {
"all": 100
},
"wind": {
"speed": 7.8,
"deg": 63,
"gust": 14.78
},
"visibility": 10000,
"pop": 1,
"rain": {
"3h": 8.62
},
"sys": {
"pod": "n"
},
"dt_txt": "2022-01-04 06:00:00"
},
{
"dt": 1641286800,
"main": {
"temp": 4.47,
"feels_like": -0.98,
"temp_min": 4.47,
"temp_max": 4.47,
"pressure": 991,
"sea_level": 991,
"grnd_level": 988,
"humidity": 93,
"temp_kf": 0
},
"weather": [
{
"id": 501,
"main": "Rain",
"description": "moderate rain",
"icon": "10d"
}
],
"clouds": {
"all": 100
},
"wind": {
"speed": 9.53,
"deg": 57,
"gust": 18.19
},
"visibility": 4030,
"pop": 1,
"rain": {
"3h": 4.5
},
"sys": {
"pod": "d"
},
"dt_txt": "2022-01-04 09:00:00"
},
{
"dt": 1641297600,
"main": {
"temp": 2.47,
"feels_like": -4.07,
"temp_min": 2.47,
"temp_max": 2.47,
"pressure": 989,
"sea_level": 989,
"grnd_level": 986,
"humidity": 95,
"temp_kf": 0
},
"weather": [
{
"id": 501,
"main": "Rain",
"description": "moderate rain",
"icon": "10d"
}
],
"clouds": {
"all": 100
},
"wind": {
"speed": 11.11,
"deg": 47,
"gust": 21.37
},
"visibility": 77,
"pop": 1,
"rain": {
"3h": 4.42
},
"sys": {
"pod": "d"
},
"dt_txt": "2022-01-04 12:00:00"
},
{
"dt": 1641308400,
"main": {
"temp": 1.66,
"feels_like": -4.74,
"temp_min": 1.66,
"temp_max": 1.66,
"pressure": 997,
"sea_level": 997,
"grnd_level": 994,
"humidity": 92,
"temp_kf": 0
},
"weather": [
{
"id": 601,
"main": "Snow",
"description": "snow",
"icon": "13d"
}
],
"clouds": {
"all": 100
},
"wind": {
"speed": 9.71,
"deg": 6,
"gust": 19.57
},
"visibility": 4352,
"pop": 1,
"snow": {
"3h": 5.76
},
"sys": {
"pod": "d"
},
"dt_txt": "2022-01-04 15:00:00"
},
{
"dt": 1641319200,
"main": {
"temp": 1.91,
"feels_like": -3.13,
"temp_min": 1.91,
"temp_max": 1.91,
"pressure": 1006,
"sea_level": 1006,
"grnd_level": 1003,
"humidity": 97,
"temp_kf": 0
},
"weather": [
{
"id": 601,
"main": "Snow",
"description": "snow",
"icon": "13n"
}
],
"clouds": {
"all": 100
},
"wind": {
"speed": 6.22,
"deg": 325,
"gust": 13.83
},
"visibility": 54,
"pop": 1,
"snow": {
"3h": 1.79
},
"sys": {
"pod": "n"
},
"dt_txt": "2022-01-04 18:00:00"
},
{
"dt": 1641330000,
"main": {
"temp": 1.61,
"feels_like": -2.74,
"temp_min": 1.61,
"temp_max": 1.61,
"pressure": 1011,
"sea_level": 1011,
"grnd_level": 1008,
"humidity": 80,
"temp_kf": 0
},
"weather": [
{
"id": 804,
"main": "Clouds",
"description": "overcast clouds",
"icon": "04n"
}
],
"clouds": {
"all": 99
},
"wind": {
"speed": 4.71,
"deg": 310,
"gust": 11.56
},
"visibility": 10000,
"pop": 0.24,
"sys": {
"pod": "n"
},
"dt_txt": "2022-01-04 21:00:00"
},
{
"dt": 1641340800,
"main": {
"temp": 0.66,
"feels_like": -3.04,
"temp_min": 0.66,
"temp_max": 0.66,
"pressure": 1014,
"sea_level": 1014,
"grnd_level": 1010,
"humidity": 79,
"temp_kf": 0
},
"weather": [
{
"id": 803,
"main": "Clouds",
"description": "broken clouds",
"icon": "04n"
}
],
"clouds": {
"all": 80
},
"wind": {
"speed": 3.4,
"deg": 283,
"gust": 10.4
},
"visibility": 10000,
"pop": 0.02,
"sys": {
"pod": "n"
},
"dt_txt": "2022-01-05 00:00:00"
},
{
"dt": 1641351600,
"main": {
"temp": 0.47,
"feels_like": -3.77,
"temp_min": 0.47,
"temp_max": 0.47,
"pressure": 1015,
"sea_level": 1015,
"grnd_level": 1012,
"humidity": 76,
"temp_kf": 0
},
"weather": [
{
"id": 800,
"main": "Clear",
"description": "clear sky",
"icon": "01n"
}
],
"clouds": {
"all": 4
},
"wind": {
"speed": 4.09,
"deg": 278,
"gust": 12.45
},
"visibility": 10000,
"pop": 0,
"sys": {
"pod": "n"
},
"dt_txt": "2022-01-05 03:00:00"
},
{
"dt": 1641362400,
"main": {
"temp": 0.48,
"feels_like": -3.77,
"temp_min": 0.48,
"temp_max": 0.48,
"pressure": 1016,
"sea_level": 1016,
"grnd_level": 1013,
"humidity": 83,
"temp_kf": 0
},
"weather": [
{
"id": 802,
"main": "Clouds",
"description": "scattered clouds",
"icon": "03n"
}
],
"clouds": {
"all": 27
},
"wind": {
"speed": 4.11,
"deg": 279,
"gust": 12.15
},
"visibility": 10000,
"pop": 0,
"sys": {
"pod": "n"
},
"dt_txt": "2022-01-05 06:00:00"
},
{
"dt": 1641373200,
"main": {
"temp": 0.79,
"feels_like": -3.36,
"temp_min": 0.79,
"temp_max": 0.79,
"pressure": 1018,
"sea_level": 1018,
"grnd_level": 1015,
"humidity": 83,
"temp_kf": 0
},
"weather": [
{
"id": 800,
"main": "Clear",
"description": "clear sky",
"icon": "01d"
}
],
"clouds": {
"all": 6
},
"wind": {
"speed": 4.07,
"deg": 288,
"gust": 12.29
},
"visibility": 10000,
"pop": 0,
"sys": {
"pod": "d"
},
"dt_txt": "2022-01-05 09:00:00"
},
{
"dt": 1641384000,
"main": {
"temp": 2.72,
"feels_like": -0.97,
"temp_min": 2.72,
"temp_max": 2.72,
"pressure": 1020,
"sea_level": 1020,
"grnd_level": 1017,
"humidity": 76,
"temp_kf": 0
},
"weather": [
{
"id": 800,
"main": "Clear",
"description": "clear sky",
"icon": "01d"
}
],
"clouds": {
"all": 6
},
"wind": {
"speed": 4.04,
"deg": 300,
"gust": 10.81
},
"visibility": 10000,
"pop": 0,
"sys": {
"pod": "d"
},
"dt_txt": "2022-01-05 12:00:00"
},
{
"dt": 1641394800,
"main": {
"temp": 2.66,
"feels_like": -0.65,
"temp_min": 2.66,
"temp_max": 2.66,
"pressure": 1021,
"sea_level": 1021,
"grnd_level": 1018,
"humidity": 76,
"temp_kf": 0
},
"weather": [
{
"id": 800,
"main": "Clear",
"description": "clear sky",
"icon": "01d"
}
],
"clouds": {
"all": 4
},
"wind": {
"speed": 3.45,
"deg": 304,
"gust": 9.24
},
"visibility": 10000,
"pop": 0,
"sys": {
"pod": "d"
},
"dt_txt": "2022-01-05 15:00:00"
},
{
"dt": 1641405600,
"main": {
"temp": 1.16,
"feels_like": -1.26,
"temp_min": 1.16,
"temp_max": 1.16,
"pressure": 1022,
"sea_level": 1022,
"grnd_level": 1019,
"humidity": 84,
"temp_kf": 0
},
"weather": [
{
"id": 800,
"main": "Clear",
"description": "clear sky",
"icon": "01n"
}
],
"clouds": {
"all": 4
},
"wind": {
"speed": 2.13,
"deg": 287,
"gust": 6.43
},
"visibility": 10000,
"pop": 0,
"sys": {
"pod": "n"
},
"dt_txt": "2022-01-05 18:00:00"
},
{
"dt": 1641416400,
"main": {
"temp": 0.63,
"feels_like": -0.93,
"temp_min": 0.63,
"temp_max": 0.63,
"pressure": 1023,
"sea_level": 1023,
"grnd_level": 1020,
"humidity": 86,
"temp_kf": 0
},
"weather": [
{
"id": 800,
"main": "Clear",
"description": "clear sky",
"icon": "01n"
}
],
"clouds": {
"all": 0
},
"wind": {
"speed": 1.43,
"deg": 257,
"gust": 3.25
},
"visibility": 10000,
"pop": 0,
"sys": {
"pod": "n"
},
"dt_txt": "2022-01-05 21:00:00"
},
{
"dt": 1641427200,
"main": {
"temp": 0.4,
"feels_like": -1.81,
"temp_min": 0.4,
"temp_max": 0.4,
"pressure": 1023,
"sea_level": 1023,
"grnd_level": 1020,
"humidity": 87,
"temp_kf": 0
},
"weather": [
{
"id": 800,
"main": "Clear",
"description": "clear sky",
"icon": "01n"
}
],
"clouds": {
"all": 0
},
"wind": {
"speed": 1.86,
"deg": 229,
"gust": 4.32
},
"visibility": 10000,
"pop": 0,
"sys": {
"pod": "n"
},
"dt_txt": "2022-01-06 00:00:00"
},
{
"dt": 1641438000,
"main": {
"temp": 0.69,
"feels_like": -1.53,
"temp_min": 0.69,
"temp_max": 0.69,
"pressure": 1022,
"sea_level": 1022,
"grnd_level": 1019,
"humidity": 84,
"temp_kf": 0
},
"weather": [
{
"id": 803,
"main": "Clouds",
"description": "broken clouds",
"icon": "04n"
}
],
"clouds": {
"all": 57
},
"wind": {
"speed": 1.9,
"deg": 193,
"gust": 6.1
},
"visibility": 10000,
"pop": 0,
"sys": {
"pod": "n"
},
"dt_txt": "2022-01-06 03:00:00"
},
{
"dt": 1641448800,
"main": {
"temp": 1.68,
"feels_like": -0.71,
"temp_min": 1.68,
"temp_max": 1.68,
"pressure": 1021,
"sea_level": 1021,
"grnd_level": 1017,
"humidity": 82,
"temp_kf": 0
},
"weather": [
{
"id": 803,
"main": "Clouds",
"description": "broken clouds",
"icon": "04n"
}
],
"clouds": {
"all": 79
},
"wind": {
"speed": 2.19,
"deg": 170,
"gust": 9.32
},
"visibility": 10000,
"pop": 0,
"sys": {
"pod": "n"
},
"dt_txt": "2022-01-06 06:00:00"
},
{
"dt": 1641459600,
"main": {
"temp": 4.29,
"feels_like": 0.69,
"temp_min": 4.29,
"temp_max": 4.29,
"pressure": 1019,
"sea_level": 1019,
"grnd_level": 1016,
"humidity": 79,
"temp_kf": 0
},
"weather": [
{
"id": 804,
"main": "Clouds",
"description": "overcast clouds",
"icon": "04d"
}
],
"clouds": {
"all": 100
},
"wind": {
"speed": 4.53,
"deg": 213,
"gust": 12.22
},
"visibility": 10000,
"pop": 0.04,
"sys": {
"pod": "d"
},
"dt_txt": "2022-01-06 09:00:00"
},
{
"dt": 1641470400,
"main": {
"temp": 4.74,
"feels_like": 0.46,
"temp_min": 4.74,
"temp_max": 4.74,
"pressure": 1017,
"sea_level": 1017,
"grnd_level": 1014,
"humidity": 92,
"temp_kf": 0
},
"weather": [
{
"id": 500,
"main": "Rain",
"description": "light rain",
"icon": "10d"
}
],
"clouds": {
"all": 100
},
"wind": {
"speed": 6.25,
"deg": 204,
"gust": 13.59
},
"visibility": 10000,
"pop": 0.71,
"rain": {
"3h": 1.28
},
"sys": {
"pod": "d"
},
"dt_txt": "2022-01-06 12:00:00"
}
],
"city": {
"id": 2643743,
"name": "London",
"coord": {
"lat": 51.5085,
"lon": -0.1257
},
"country": "GB",
"population": 1000000,
"timezone": 0,
"sunrise": 1641024368,
"sunset": 1641052893
}
}
in weatherData.dart
class WeatherData {
String? placeName;
num? temperature;
num? feels_like;
num? pressure;
num? humidity;
num? wind_speed;
WeatherData({
this.placeName,
this.temperature,
this.feels_like,
this.pressure,
this.humidity,
this.wind_speed,
});
WeatherData.fromJson(Map<String, dynamic> json) {
placeName = json['city']['name'];
temperature = json['list'][0]['main']['temp'];
feels_like = json['list'][0]['main']['temp'];
pressure = json['list'][0]['main']['temp'];
humidity = json['list'][0]['main']['temp'];
wind_speed = json['list'][0]['main']['temp'];
}
}
in forecastData.dart
import 'package:forecast/models/weather_data.dart';
class ForecastData {
final List list;
ForecastData({required this.list});
factory ForecastData.fromJson(Map<String, dynamic> json) {
var list = json['list']?.map((e) => e)?.toList(growable: true) ?? [];
list.forEach((e) {
WeatherData w = WeatherData(
placeName: json['city']['name'],
temperature: e['main']['temp'],
feels_like: e['main']['temp'],
pressure: e['main']['temp'],
humidity: e['main']['temp'],
wind_speed: e['main']['temp']);
list.add(w);
print(w);
});
return ForecastData(
list: list,
);
}
}
In weather_item.dart
import 'package:flutter/material.dart';
import 'package:forecast/models/weather_data.dart';
class WeatherItem extends StatelessWidget {
final WeatherData weather;
const WeatherItem({Key? key, required this.weather}) : super(key: key);
@override
Widget build(BuildContext context) {
return Card(
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
children: <Widget>[
Text('${weather.placeName}',
style: const TextStyle(color: Colors.white)),
Text('${weather.temperature}',
style: const TextStyle(color: Colors.white, fontSize: 32.0)),
Text('${weather.feels_like.toString()}°F',
style: const TextStyle(color: Colors.white)),
Text('${weather.humidity}',
style: const TextStyle(color: Colors.white)),
Text('${weather.wind_speed}',
style: const TextStyle(color: Colors.white)),
],
),
),
);
}
}
in main.dart
import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:forecast/models/forecast_data.dart';
import 'package:forecast/models/weather_data.dart';
import 'package:forecast/widgets/weather.dart';
import 'package:forecast/widgets/weather_item.dart';
import 'package:http/http.dart' as http;
void main() => runApp(const MyApp());
class MyApp extends StatefulWidget {
const MyApp({Key? key}) : super(key: key);
@override
State<MyApp> createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
WeatherData weatherData = WeatherData();
ForecastData? forecastData;
bool isLoading = false;
@override
void initState() {
super.initState();
loadWeather();
loadForecast();
}
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Weather App',
theme: ThemeData(
primarySwatch: Colors.red,
),
home: Scaffold(
backgroundColor: Colors.blueGrey,
appBar: AppBar(
title: const Text('Flutter Weather App'),
),
body: Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
Expanded(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Padding(
padding: const EdgeInsets.all(8.0),
child: Weather(weather: weatherData)),
],
),
),
Padding(
padding: const EdgeInsets.all(8.0),
child: IconButton(
icon: const Icon(Icons.refresh),
tooltip: 'Refresh',
onPressed: () {},
color: Colors.white,
),
),
SafeArea(
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Container(
height: 200.0,
child: ListView.builder(
itemBuilder: (context, index) => WeatherItem(
weather: forecastData?.list.elementAt(index))),
),
),
),
],
),
),
),
);
}
loadWeather() async {
setState(() {
isLoading = true;
});
String url =
'https://api.openweathermap.org/data/2.5/forecast?q=London&units=metric&appid=API';
http.Response response = await http.get(Uri.parse(url));
if (response.statusCode == 200 && response.statusCode == 200) {
return setState(() {
weatherData = WeatherData.fromJson(jsonDecode(response.body));
isLoading = false;
});
}
}
loadForecast() async {
setState(() {
isLoading = true;
});
String url =
'https://api.openweathermap.org/data/2.5/forecast?q=London&units=metric&appid=API';
http.Response response = await http.get(Uri.parse(url));
if (response.statusCode == 200 && response.statusCode == 200) {
return setState(() {
forecastData = ForecastData.fromJson(jsonDecode(response.body));
isLoading = false;
});
}
}
}
}
When I debug it I get an error in weather_item.dart that says following
NoSuchMethodError (NoSuchMethodError: The getter 'placeName' was called on null. Receiver: null Tried calling: placeName)
and I also get an error that says type Null is not a subtype of type 'WeatherData' on the screen emulator when I run it..
I can only get weatherData rendered not forecastData.. any help is appreciated!
CodePudding user response：
try using futurebuilder when printing data i'm not sure if you might be trying to reach them before the data arrives
CodePudding user response：
On your model class, variables are nullable
class WeatherData {
String? placeName;
Text widget doesn't take null value, therefore you need to handle it.
You can provide default value like
Text('${weather.placeName?? "default value"}',
Or don't render while it is null
if(weather.placeName!=null)Text('${weather.placeName!}'
Check, I'm using ! after making sure it will never get null.