'flutter' doesnt recognize as a name in cmdlet - json

Question

im following a tutorial of flutter about using json and serialization.
Im trying to execute a command in the terminal in a flutter proyect in vscode,
this is the class
import 'package:json_annotation/json_annotation.dart';
part 'mensaje.g.dart';
#JsonSerializable()
class Mensaje{
final String subject;
final String body;
Mensaje(this.subject,this.body);
Mensaje.fromJson(Map<String, dynamic> json):
subject=json['subject'],
body=json['body'];
}
I first add the dependecies in pubspec.yaml:
dev_dependencies:
build_runner:
json_serializable:
then i try to execute in the terminal in vscode this line:
flutter packages pub run build_runner build
and the error:
(flutter its not recognize as a cmdlet name or function... )
flutter : El término 'flutter' no se reconoce como nombre de un cmdlet, función,
archivo de script o programa ejecutable. Compruebe si escribió correctamente el
nombre o, si incluyó una ruta de acceso, compruebe que dicha ruta es correcta e
inténtelo de nuevo.
En línea: 1 Carácter: 1
+ flutter packages pub run build_runner build
+ ~~~~~~~
+ CategoryInfo : ObjectNotFound: (flutter:String) [], CommandNotFoundEx
ception
+ FullyQualifiedErrorId : CommandNotFoundException

Answer 1

It seems that you need to add your Flutter SDK path to the environment variable (e.g. C:\src\flutter) for windows. Also you can follow the Flutter documentation for proper installation on different OS:
Windows
macOS
linux
Chrome OS
If this is not the case, you can try to restart your VSCode application.