dart JSON String convert to List String

Question

I have an API that calls the json String array as follows:

[
  "006.01.01",
  "006.01.01 1090",
  "006.01.01 1090 1090.950",
  "006.01.01 1090 1090.950 052",
  "006.01.01 1090 1090.950 052 A",
  "006.01.01 1090 1090.950 052 A 521219",
  "006.01.01 1090 1090.950 052 A 521219",
  "006.01.01 1090 1090.950 052 A 521219",
  "006.01.01 1090 1090.950 052 A 521219",
  "006.01.01 1090 1090.950 052 A 521219",
  "006.01.01 1090 1090.950 052 B",
  "006.01.01 1090 1090.950 052 B 521211",
  "006.01.01 1090 1090.950 052 B 521211",
  "006.01.01 1090 1090.994",
  "006.01.01 1090 1090.994 001",
  "006.01.01 1090 1090.994 001 A",
  "006.01.01 1090 1090.994 001 A 511111",
  "006.01.01 1090 1090.994 001 A 511111",
  "006.01.01 1090 1090.994 001 A 511111",
  "006.01.01 1090 1090.994 001 A 511111"
]

I intend to convert the json to the List in the dart. I tried the script below :

json.decode(response.body).cast<List<String>();

but it didn't work, how should the script be correct?

lrn · Accepted Answer · 2019-09-10 13:55:59Z

63

The result of parsing a JSON list is a List<dynamic>. The return type of jsonDecode is just dynamic.

You can cast such a list to a List<String> as

List<String> stringList = (jsonDecode(input) as List<dynamic>).cast<String>();

You can also just use it as a List<dynamic> and then assign each value to String:

List<dynamic> rellyAStringList = jsonDecode(input);
for (String string in reallyAStringList) { ... }

The effect is approximately the same - each element is checked for being a string when it is taken out of the list.

edited Sep 10, 2019 at 13:55

answered Nov 20, 2018 at 7:14

lrn

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Comments

vishwajit76 · Accepted Answer · 2021-07-18 11:48:18Z

Convert Json Data To List

List<String> data = [
   "006.01.01",
   "006.01.01 1090",
   "006.01.01 1090 1090.950",
   "006.01.01 1090 1090.950 052",
   "006.01.01 1090 1090.950 052 A",
   "006.01.01 1090 1090.950 052 A 521219",
   "006.01.01 1090 1090.950 052 A 521219",
   "006.01.01 1090 1090.950 052 A 521219",
   "006.01.01 1090 1090.950 052 A 521219",
   "006.01.01 1090 1090.950 052 A 521219",
   "006.01.01 1090 1090.950 052 B",
   "006.01.01 1090 1090.950 052 B 521211",
   "006.01.01 1090 1090.950 052 B 521211",
   "006.01.01 1090 1090.994",
   "006.01.01 1090 1090.994 001",
   "006.01.01 1090 1090.994 001 A",
   "006.01.01 1090 1090.994 001 A 511111",
   "006.01.01 1090 1090.994 001 A 511111",
   "006.01.01 1090 1090.994 001 A 511111",
   "006.01.01 1090 1090.994 001 A 511111"
];

//your json string
String jsonString = json.encode(data);

//convert json string to list
List<String> newData = List<String>.from(json.decode(jsonString));

Sagar Bahadur Tamang · Accepted Answer · 2018-11-19 14:26:59Z

Try this one. Hope it helps.

import 'dart:convert';

void main() {
  String jsonResponse = '''
    ["006.01.01",
    "006.01.01 1090",
    "006.01.01 1090 1090.950",
    "006.01.01 1090 1090.950 052",
    "006.01.01 1090 1090.950 052 A",
    "006.01.01 1090 1090.950 052 A 521219",
    "006.01.01 1090 1090.950 052 A 521219",
    "006.01.01 1090 1090.950 052 A 521219",
    "006.01.01 1090 1090.950 052 A 521219",
    "006.01.01 1090 1090.950 052 A 521219",
    "006.01.01 1090 1090.950 052 B",
    "006.01.01 1090 1090.950 052 B 521211",
    "006.01.01 1090 1090.950 052 B 521211",
    "006.01.01 1090 1090.994",
    "006.01.01 1090 1090.994 001",
    "006.01.01 1090 1090.994 001 A",
    "006.01.01 1090 1090.994 001 A 511111",
    "006.01.01 1090 1090.994 001 A 511111",
    "006.01.01 1090 1090.994 001 A 511111",
    "006.01.01 1090 1090.994 001 A 511111"]
  ''';

  dynamic jsonParsed = json.decode(jsonResponse);

//   print(jsonParsed);

  print(jsonParsed[5]);
}

Erlang Parasu · Accepted Answer · 2022-12-29 05:09:47Z

1

If the outermost data is an object and you want to list it inside you can use the following:

    var json = '{"id":1,"tags":["a","b","c"]}';
    var data = jsonDecode(json);

    List<dynamic> rawTags = data['tags'];

    List<String> tags = rawTags.map(
      (item) {
        return item as String;
      },
    ).toList();

    print(tags);

answered Dec 29, 2022 at 5:09

Erlang Parasu

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Comments

ser duer · Accepted Answer · 2023-10-12 11:36:50Z

A possibility to convert any dynamic Json to List of Strings maybe this approach:

List<String> _data = []; // List to store the result
const int MAXL = 40; // max length lines
String line = ''; // A single line
int i = 0; // To identify level recursion

void makeArrayList (Map ret) {

  // function to call at any level of recursion
  void CheckKeyValue (Map data) {
    i++;

    data.forEach((key, value) {
      if (value is Map) {
        _data.add('** $key *$i*');
        CheckKeyValue (value);
        i--;
      } else {
        if (value is List) {
          for (var el in value) {
            if (el is Map) {
              CheckKeyValue (el);
              i--;
            } else {
              line = '$key: $value'.length > MAXL ?
                     line.substring(0, MAXL) : '$key: $value';

              _data.add(line);
            }
            _data.add(''); // \n line
          }
        } else {
          line = '$key: $value'.length > MAXL ?
                 line.substring(0, MAXL) : '$key: $value';

          _data.add(line);
        }
      }
    });
  }

  CheckKeyValue (ret);
}

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