How to access JSON nested data in flutter dart - json

Question

I have the below json data, wherein I want to access the values inside the feeling_percentage.
{
"status": "200",
"data": {
"feeling_percentage": {
"Happy": "0",
"Sad": "0",
"Energetic": "0",
"Calm": "0",
"Angry": "0",
"Bored": "0"
},
}
}
I am able to fetch it using the below API code
Future<List<Data>> makePostRequest() async {
List<Data> list = [];
final uri = Uri.parse('<api>');
final headers = {'Content-Type': 'application/json', 'X-Api-Key':'<api_key>'};
Map<String, dynamic> body = {'user_id': 3206161992, 'feeling_date': '15-04-2022'};
String jsonBody = json.encode(body);
final encoding = Encoding.getByName('utf-8');
Response response = await post(
uri,
headers: headers,
body: jsonBody,
encoding: encoding,
);
int statusCode = response.statusCode;
String responseBody = response.body;
print('response body'+ responseBody);
}
After reading few articles, still not able to figure out how do I access the percentage of happy, sad inside the feeling_percentage.
I have created the model as
class Data{
FeelingPercentage feelingPercentage;
Data(
{required this.feelingPercentage});
factory Data.fromJson(Map<String, dynamic> json) {
return Data(
feelingPercentage: FeelingPercentage.fromJson(json["data"]),
);
}
}
class FeelingPercentage {
String? happy;
String? sad;
String? energetic;
String? calm;
String? angry;
String? bored;
FeelingPercentage({this.happy, this.sad, this.energetic, this.calm, this.angry, this.bored});
factory FeelingPercentage.fromJson(Map<String, dynamic> json) {
return FeelingPercentage(
happy: json["happy"] as String,
sad: json["sad"] as String,
energetic: json["energetic"] as String,
calm: json["calm"] as String,
angry: json["angry"] as String,
bored: json["bored"] as String,
);
}
}

Answer 1

Another way:
import 'package:fast_json/fast_json_selector.dart' as parser;
void main() {
final path = '{}.data.{}.feeling_percentage';
final level = path.split('.').length;
void select(parser.JsonSelectorEvent event) {
final levels = event.levels;
if (levels.length == level && levels.join('.') == path) {
print(event.lastValue);
event.lastValue = null;
}
}
parser.parse(_source, select: select);
}
const _source = '''
{
"status": "200",
"data": {
"feeling_percentage": {
"Happy": "0",
"Sad": "0",
"Energetic": "0",
"Calm": "0",
"Angry": "0",
"Bored": "0"
}
}
}''';
Output:
{Happy: 0, Sad: 0, Energetic: 0, Calm: 0, Angry: 0, Bored: 0}

Answer 2

You can use this website to convert your JSON object to a dart class.
it automatically creates the fromJson function, which can be used to pass JSON and receive the Dart objects.

Answer 3

Change this line in your model feelingPercentage: FeelingPercentage.fromJson(json["data"]), to feelingPercentage: FeelingPercentage.fromJson(json["data"]["feeling_percentage"]),
This will fix your issue.

Answer 4

You can do a JSON decode that will will result in a map, and then do the assigned like you are doing on your from Json factory, but as another constructor instead:
Class
Todo.fromMap(Map map) :
this.title = map['title'],
this.completed = map['completed'];
In use
Todo.fromMap(json.decode(item))

Answer 5

First decode response.body, then create FeelingPercentage object from json["data"]["feeling_percentage"] map.
Future<FeelingPercentage> makePostRequest() async {
...
final json = json.decode(response.body);
return FeelingPercentage.fromJson(json["data"]["feeling_percentage"])
}
class FeelingPercentage {
String? happy;
String? sad;
String? energetic;
String? calm;
String? angry;
String? bored;
FeelingPercentage({this.happy, this.sad, this.energetic, this.calm, this.angry, this.bored});
factory FeelingPercentage.fromJson(Map<String, dynamic> json) {
return FeelingPercentage(
happy: json["Happy"] as String,
sad: json["Sad"] as String,
energetic: json["Energetic"] as String,
calm: json["Calm"] as String,
angry: json["Angry"] as String,
bored: json["Bored"] as String,
);
}
}