I am using Flutter, MongoDB, Mongoose, NodeJS and SocketIO.

In MongoDB I am storing a list<object> object, querying the object with model.find() and passing the results back to the client.

But on the client side I am receiving a list<dynamic> object and I don't understand how to convert it to a list<Object> object.

Server-side code

socket.on("event", async() => {
    var objectList =await Model.find();
    socket.emit("event",objectList);
});

Client-side code

function() {
    _socketClient?.on("event",(objectList) { //objectList is a here a list<dynamic>
    List<Object> list = objectList.cast<Object>();
    //Here I am get an exception
    Unhandled Exception: type 'List<dynamic>' is not a subtype of type 'String'
  });
}

I am using Flutter, MongoDB, Mongoose, NodeJS and SocketIO.

In MongoDB I am storing a list<object> object, querying the object with model.find() and passing the results back to the client.

But on the client side I am receiving a list<dynamic> object and I don't understand how to convert it to a list<Object> object.

Server-side code

socket.on("event", async() => {
    var objectList =await Model.find();
    socket.emit("event",objectList);
});

Client-side code

function() {
    _socketClient?.on("event",(objectList) { //objectList is a here a list<dynamic>
    List<Object> list = objectList.cast<Object>();
    //Here I am get an exception
    Unhandled Exception: type 'List<dynamic>' is not a subtype of type 'String'
  });
}

• flutter
• mongodb
• socket.io

1 Answer 1

To resolve this issue, you need to cast each element of the objectList to the appropriate type instead of trying to cast the entire list at once.

Here's how you can convert the received list of objects to a List in your Flutter client:

function() {  
  _socketClient?.on("event", (objectList) {  
    List<Object> list = [];  
      
    for (var obj in objectList) {  
      list.add(obj as Object);  
    }  
      
    // Now you have a List<Object> containing the objects received from the server  
  });  
}