Flutter Error: type 'AddressInfo' is not a

问题:

I made a model class and forward it to a put api. but it shows the error that

type 'AddressInfo' is not a subtype of type 'String' in type cast

The class is serialized properly, I checked the output of the map.This error occurs during http put request

Model Class

@JsonSerializable()
class AddressInfo{
  String city;
  List<String> operationAreas=new List();

  AddressInfo(
      this.city,
      this.operationAreas
      );

  factory AddressInfo.fromJson(Map<String, dynamic> json) => _$AddressInfoFromJson(json);
  Map<String, dynamic> toJson() => _$AddressInfoToJson(this);
}

API Call

Map input = addressinfo.toJson();
    String jsonData = json.encode(input);
    debugPrint("API CALLING json" + jsonData);

    http.Response response = await
    http.put(Apis.SIGNUP,
        body: input ); // post api call

Error

 type 'AddressInfo' is not a subtype of type 'String' in type cast
E/flutter ( 8969): #0      CastMap.forEach.<anonymous closure> (dart:_internal/cast.dart:286:25)
E/flutter ( 8969): #1      __InternalLinkedHashMap&_HashVMBase&MapMixin&_LinkedHashMapMixin.forEach (dart:collection/runtime/libcompact_hash.dart:370:8)
E/flutter ( 8969): #2      CastMap.forEach (dart:_internal/cast.dart:285:13)
E/flutter ( 8969): #3      mapToQuery (package:http/src/utils.dart:17:7)
E/flutter ( 8969): #4      Request.bodyFields= (package:http/src/request.dart:128:17)
E/flutter ( 8969): #5      BaseClient._sendUnstreamed (package:http/src/base_client.dart:163:17)
E/flutter ( 8969): <asynchronous suspension>
E/flutter ( 8969): #6      BaseClient.put (package:http/src/base_client.dart:76:7)
E/flutter ( 8969): #7      put.<anonymous closure> (package:http/http.dart:94:16)
E/flutter ( 8969): #8      _withClient (package:http/http.dart:166:20)
E/flutter ( 8969): <asynchronous suspension>
E/flutter ( 8969): #9      put (package:http/http.dart:93:5)
E/flutter ( 8969): #10     signup (package:careio_cross_platform/screens/PricingSelectionScreen.dart:175:5)

回答1:

Replace this :

http.put(Apis.SIGNUP,
    body: input ); 

by this:

http.put(Apis.SIGNUP,
    body: json.encode(input) );