type 'int' is not a subtype of type 'String' in type cast when sending a post request

I have a weird error showing up when sending a post request.

// this map is passed to a function
final Map<String, dynamic> activityData = {
  "userId": 1,
  "name": activityName.text,
  "description": activityDescription.text,
  "startAt": activityStartAt.text,
  "endsAt": activityEndAt.text,
  "lat": _latitude,
  "long": _longitude,
  "category": 2,
  "status": "pending"
};

// this code bellow is inside a async function
final http.Response response =
        await http.post(Uri.encodeFull(url), body: activityData);

this is the error :

E/flutter (32582): [ERROR:flutter/shell/common/shell.cc(184)] Dart Error: Unhandled exception:
E/flutter (32582): type 'int' is not a subtype of type 'String' in type cast
E/flutter (32582): #0      CastMap.forEach.<anonymous closure> (dart:_internal/cast.dart:286:25)
E/flutter (32582): #1      __InternalLinkedHashMap&_HashVMBase&MapMixin&_LinkedHashMapMixin.forEach (dart:collection/runtime/libcompact_hash.dart:370:8)
E/flutter (32582): #2      CastMap.forEach (dart:_internal/cast.dart:285:13)
E/flutter (32582): #3      mapToQuery (package:http/src/utils.dart:17:7)
E/flutter (32582): #4      Request.bodyFields= (package:http/src/request.dart:128:17)
E/flutter (32582): #5      BaseClient._sendUnstreamed (package:http/src/base_client.dart:163:17)
E/flutter (32582): <asynchronous suspension>
E/flutter (32582): #6      BaseClient.post (package:http/src/base_client.dart:54:7)
E/flutter (32582): #7      post.<anonymous closure> (package:http/http.dart:70:16)
E/flutter (32582): #8      _withClient (package:http/http.dart:166:20)
E/flutter (32582): <asynchronous suspension>
E/flutter (32582): #9      post (package:http/http.dart:69:5)
E/flutter (32582): #10     _MainModel&Model&ConnectedModel&UsersModel&ActivitiesModel.createActivity (package:activmap/scoped-models/connectedModel.dart:62:15)
E/flutter (32582): <asynchronous suspension>
E/flutter (32582): #11     _NewActivityState.save (package:activmap/pages/newActivity.dart:271:11)
E/flutter (32582): <asynchronous suspension>
E/flutter (32582): #12     _NewActivityState.build.<anonymous closure> (package:activmap/pages/newActivity.dart:248:30)
E/flutter (32582): #13     _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:507:14)
E/flutter (32582): #14     _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:562:30)
E/flutter (32582): #15     GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
E/flutter (32582): #16     TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:242:9)
E/flutter (32582): #17     TapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:175:7)
E/flutter (32582): #18     PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:315:9)
E/flutter (32582): #19     PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:73:12)
E/flutter (32582): #20     PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:101:11)
E/flutter (32582): #21     _WidgetsFlutterBinding&BindingBase&GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:180:19)
E/flutter (32582): #22     _WidgetsFlutterBinding&BindingBase&GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:158:22)
E/flutter (32582): #23     _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:138:7)
E/flutter (32582): #24     _WidgetsFlutterBinding&BindingBase&GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:101:7)
E/flutter (32582): #25     _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:85:7)
E/flutter (32582): #26     _invoke1 (dart:ui/hooks.dart:168:13)
E/flutter (32582): #27     _dispatchPointerDataPacket (dart:ui/hooks.dart:122:5)

I have it working fine on another screen the only difference that I can see is that the one that's working only have Strings, while this one has int, double and String.

Solution

To fix your issue you just have to encode the data before sending.

 import 'dart:convert';
 ...

 final http.Response response =
    await http.post(Uri.encodeFull(url), body: json.encode(activityData));

If your API doesn't support JSON, then you just have to pass all your data as String.

    final Map<String, dynamic> activityData = {
      "user_id": "1",
      "name": activityName.text,
      "description": activityDescription.text,
      "startAt": activityStartAt.text,
      "endsAt": activityEndAt.text,
      "lat": "$_latitude",
      "long": "$_longitude",
      "category": "2",
      "status": "pending"
    };

     final http.Response response =
    await http.post(Uri.encodeFull(url), body: activityData);