Flutter: how to decode this complex JSON string

问题

From my REST API a JSON string is received as

{"total":"30","results":[ {"ID":"1809221034017","DATE":"2018-09-22","REG":"(E9)","START":"10:40","END":"10:48"}, {"ID":"1809221337250","DATE":"2018-09-22","REG":"(E4)","START":"13:43","END":"13:57"}, {"ID":"1809161032213","DATE":"2018-09-16","REG":"(E1)","START":"11:04","END":"11:13"}]}

The total field tells me that the database contains in total 30 records, the requested data (only 3 rows) is included in the results section.

I need to parse the data, so I can show the results in ListView. I managed to do this with a simple JSON string, but not with this complex JSON string. Unfortunately I am not able to change the output of the web service since this is hosted by a 3rd party.

Any help, or a code example, is appreciated.

Thanks in advance

回答1:

Read first my other answer here.

Then I suggest you to use a class generation library like quicktype.

Using quick type for example you can easily and automatically genearate your moidel class in dart using your JSON. Here the generated file.

quicktype --lang dart --all-properties-optional https://www.shadowsheep.it/so/53968769/testjson.php -o my_json_class.dart

Then use it in code:

import 'my_json_class.dart';
import 'package:http/http.dart' as http;

var response = await http.get('https://www.shadowsheep.it/so/53968769/testjson.php');
    var myClass = MyJsonClass.fromJson(jsonDecode(response.body));
    for(var result in myClass.results.toList()) {
       print(result?.id);
    }

N.B. If you'll master a code generator library, then you'll be able to parse any type of JSON coming from a REST API and you'll have more time for fun.

回答2:

So here we can see that there is a JSON object having two values a JSON array and a total number.Sometimes the internet services don't return the full value but only a part due to network issues. So now in the array we have number of results objects with an ID,DATE,REG,START,END. If you format the JSON you will decode it easily.

回答3:

i recommend this article: https://medium.com/flutter-community/parsing-complex-json-in-flutter-747c46655f51

 class Result
            {
               String id ;
                 String date;
                 String reg ;
                 String start;
                 String end ;

            Result({this.date,this.end,this.id,this.reg,this.start});

            factory Result.fromJson(Map<String, dynamic> parsedJson) {

             return new Result(
               id: parsedJson['ID'],
               date: parsedJson['DATE'],
               reg: parsedJson['REG'],
               start: parsedJson['START'],
               end: parsedJson['END'],
             );
          }
            }

             class Results
            {
                 String total;
                 List<Result> results;

                Results({this.results, this.total});
                factory Results.fromJson(Map<String, dynamic> parsedJson) {
                var list = parsedJson['results'][] as List;
                return new Results(
                total: parsedJson['total'],
                results: list.map((i) => Result.fromJson(i)).toList());
            }}

来源：https://stackoverflow.com/questions/53968769/flutter-how-to-decode-this-complex-json-string

标签

json

Flutter

decode