How to encode Map into Json in Dart?-CodePudding

I am trying to convert Map<DateTime,List> into json with following code:

String ecoded = json.encode({
  DateTime.now(): ["Sample data", 3,true,"Example", 2],
});

But compiler give following error:

E/flutter (11773): [ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled 
Exception: Converting object to an encodable object failed: _LinkedHashMap len:1
E/flutter (11773): #0      _JsonStringifier.writeObject 
(dart:convert/json.dart:688:7)
E/flutter (11773): #1      _JsonStringStringifier.printOn 
(dart:convert/json.dart:877:17)
E/flutter (11773): #2      _JsonStringStringifier.stringify 
(dart:convert/json.dart:862:5)
E/flutter (11773): #3      JsonEncoder.convert (dart:convert/json.dart:262:30)
E/flutter (11773): #4      JsonCodec.encode (dart:convert/json.dart:172:45)

I converted many times Map into json but in all cases Map was something like that:

Map<String,dynamic>

This error is occurring because there is List

If anyone know how to convert Map<DateTime,List> into json then Answer this question.

Thanks

CodePudding user response：

Json only supports Strings as keys. So if you want to use DateTimes as keys you have to manually convert it first:

String ecoded = json.encode({
    DateTime.now().toString(): ["Sample data", 3,true,"Example", 2],
});

Map<String, dynamic> result = datetimeMap.map((k, v) => MapEntry('$k', v))

CodePudding user response：

In dart programming, json.encode(DateTime.Now()) which is not possible. You need to convert by using Iso8601String() or toString()

String ecoded = json.encode({
  DateTime.now().toIso8610String(): ["Sample data", 3,true,"Example", 2],
});