Let us start here, from square one. No, from Zero!

api/resources/dart/spiceapi-websocket/src/response.dart

@@ -0,0 +1,35 @@
+part of spiceapi;
+
+class Response {
+
+  String _json;
+  int _id;
+  List _errors;
+  List _data;
+
+  Response.fromJson(String json) {
+    this._json = json;
+    var obj = jsonDecode(json);
+    this._id = obj["id"];
+    this._errors = obj["errors"];
+    this._data = obj["data"];
+  }
+
+  void validate() {
+
+    // check for errors
+    if (_errors.length > 0) {
+      // TODO: add all errors
+      throw APIError(_errors[0].toString());
+    }
+  }
+
+  List getData() {
+    return _data;
+  }
+
+  String toJson() {
+    return _json;
+  }
+
+}