how to stringify json in flutter

Question

In flutter(dart), it is easy to deserialize Json and get a token from it, but when I try to serialize it again, the quotation marks around the keys and values with disappear.

String myJSON = '{"name":{"first":"foo","last":"bar"}, "age":31, "city":"New York"}';
var json = JSON.jsonDecode(myJSON); //_InternalLinkedHashMap
var nameJson = json['name']; //_InternalLinkedHashMap
String nameString = nameJson.toString();

Although the nameJson have all the double quotations, the nameString is

{first: foo, last: bar}

(true answer is {"first": "foo", "last": "bar"})

how to preserve Dart to remove the "s?

I want a json string that can use again for JsonDecoder, when the quotation marks remove, the string is not a valid json no longer — Mehdi Khademloo
– Mehdi Khademloo, Commented Feb 1, 2019 at 22:07

dominicm00 · Accepted Answer · 2019-02-01 22:15:04Z

55

When encoding the object back into JSON, you're using .toString(), which does not convert an object to valid JSON. Using jsonEncode fixes the issue.

import 'dart:convert';

void main() {
  String myJSON = '{"name":{"first":"foo","last":"bar"}, "age":31, "city":"New York"}';
  var json = jsonDecode(myJSON);
  var nameJson = json['name'];
  String nameString = jsonEncode(nameJson); // jsonEncode != .toString()
  print(nameString); // outputs {"first":"foo","last":"bar"}
}

answered Feb 1, 2019 at 22:15

dominicm00

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Osama Remlawi · Accepted Answer · 2023-03-21 14:07:45Z

3

Let's say you have a map, and you want to stringify it into a string variable, then all what you need to do is:

Map<String, dynamic> map = {...};
String stringifiedString = jsonEncode(map);

The output will be:

"{\"name\":{\"first\":\"foo\",\"last\":\"bar\"}, \"age\":31, \"city\":\"New York\"}"

You can read more about this on the documentation page.

answered Mar 21, 2023 at 14:07

Osama Remlawi

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