JsonUnsupportedObjectError was thrown while handling a gesture - Flutter - json

Question

I'm working on a datable that displays some users with their information and in which each row can change its 'role' and be removed from the site it's associated with by sending a JSON message to kafka into the DB. For this purpose, I added a dropdown button to change their roles and a 'remove' button to remove the user from the site.
But whenever I trigger the 'remove button' or change the role dropdown validation, I receive the following error:
EXCEPTION CAUGHT BY GESTURE
The following JsonUnsupportedObjectError was thrown while handling a gesture:
Converting object to an encodable object failed: Instance of 'User'
When the exception was thrown, this was the stack:
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 266:49
throw_
dart-sdk/lib/convert/json.dart 794:7
writeObject
dart-sdk/lib/convert/json.dart 875:7
writeMap
dart-sdk/lib/convert/json.dart 830:21
writeJsonValue
dart-sdk/lib/convert/json.dart 785:9
writeObject
dart-sdk/lib/convert/json.dart 983:16
printOn
dart-sdk/lib/convert/json.dart 968:5
stringify
dart-sdk/lib/convert/json.dart 345:30
convert
dart-sdk/lib/convert/json.dart 231:45
encode
dart-sdk/lib/convert/json.dart 114:10
jsonEncode
packages/frontend/data/socketDataStreamController.dart 343:33
editUserSite
packages/frontend/screens/pagesNavigator/sitesManagementPage/sitesUsers.dart
237:64 <fn>
My user class is the following:
class User {
final String userId;
String firstName;
String lastName;
String email;
final String company;
String phoneNumber;
final String userRole;
final Uint8List imageBuffer;
final bool admin;
String? authToken;
String country;
String language;
List<dynamic> notifications;
String siteRole;
User(
{required this.userId,
required this.firstName,
required this.lastName,
required this.email,
required this.company,
required this.phoneNumber,
required this.imageBuffer,
required this.userRole,
required this.admin,
required this.country,
required this.language,
required this.notifications,
required this.siteRole
});
/// Generate new user object from json
User.fromJSON(
Map<String, dynamic> json,
) : userId = json["_id"] ?? "",
firstName = json["firstName"] ?? "",
lastName = json["lastName"] ?? "",
email = json["email"] ?? "",
company = json["company"] ?? "",
phoneNumber = json["phoneNumber"] ?? "",
userRole = json["userRole"] ?? "",
imageBuffer = Uint8List(0),
authToken = json["token"],
admin = json["admin"] ?? false,
country = json["country"] ?? "",
language = json["language"] ?? "",
notifications = json["notifications"] ?? [],
siteRole = json["siteRole"] ?? "";
#override
String toString() {
return "User: ${jsonEncode({
"userId": userId,
"name": "$firstName $lastName",
"email": email,
"company": company,
"phoneNumber": phoneNumber,
"userRole": userRole,
"admin": admin,
"country": country,
"language": language,
"siteRole": siteRole
})}";
}
}
This is the Button inside the alert dialog that triggers the JSON
ElevatedButton(
child: Text('Yes, remove.'),
style: ElevatedButton.styleFrom(
backgroundColor: Colors.grey),
onPressed: () {
final userRoleChange = {
"siteId": widget.site.id,
"userId": user,
"status": 0
};
globals.socketController.editUserSite(userRoleChange);
Navigator.of(context).pop()
},
),
This is the main.js backend function that connects with kafka:
socket.on("editUserSite", async (message) => {
// console.log('on editUserSite')
let result = true;
const userData = JSON.parse(message);
// console.log(userData)
var requestId = Date.now().toString() + "_backend"
let dbRequest = topicsLib["userDB-read"]
dbRequest.query_id = requestId,
dbRequest.collection = "sites",
dbRequest.object_id = [userData.siteId]
dbRequest.requester = "backend"
dbRequest.field = [
"users"
]
adminProducer.send( {
topic: "userDB-read",
messages: [{ value: JSON.stringify(dbRequest) }],
});
const dbUserResponse = await kafkaDbResponse(requestId, logger);
if (typeof(dbUserResponse.data) == String) {
logger.error("Error when fetching data" + dbUserResponse)
throw new Error("Error when fetching data")
}
// console.log(dbUserResponse)
usersList = []
for (d of dbUserResponse.data[0].users) {
usersList.push(d)
}
// console.log(usersList)
objIndex = usersList.findIndex((obj => obj.userId == userData.userId));
console.log(objIndex)
//The users dont exist , we need to add a user
if (objIndex == -1) {
usersList.push({
userId:userData.userId,
role:userData.role,
})
} else {
//Update or Remove user
if (userData.status == 0) {
usersList.splice(objIndex, 1);
} else {
usersList[objIndex].role = userData.role
}
}
console.log(usersList)
let dbUpdatePayload = topicsLib["userDB-write"]
const dbUpdateMessageId = hashCode(Date.now().toString());
dbUpdatePayload.query_id = dbUpdateMessageId,
dbUpdatePayload.collection = "sites",
dbUpdatePayload.object_id = userData.siteId
dbUpdatePayload.requester = "backend"
dbUpdatePayload.append = false
dbUpdatePayload.field = ["users"]
dbUpdatePayload.data = [usersList]
dbUpdatePayload.convert_to_object_id = true
dbUpdatePayload.field_to_object_id = "userId"
console.log(dbUpdatePayload)
await adminProducer.send( {
topic: "userDB-write",
messages: [
{
value: JSON.stringify(dbUpdatePayload),
},
],
});
//#ts-ignore
await sleep(80);
if (result) {
response = {
'status' : 200,
'message' : 'Site updated',
}
} else {
response = {
'status' : 400,
'message' : 'error',
}
}
socket.emit("editUserSiteResponse", response)
})
And this is the socketdataStreamcontroller that consumes it on the frontend:
void editUserSite(userRoleChange) {
if (!socket.connected) {
return;
}
socket.emit("editUserSite", jsonEncode(userRoleChange));
}
How can I solve this issue?