flutter - How to use Future<bool> in Widget

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I have a Future function in my Provider Repository. However it is Future<bool> since I need async for http request.

Future<bool> hasCard() async {
    String token = await getToken();
    var body = jsonEncode({"token": token, "userID": user.getUserID()});
    var res = await http.post((baseUrl + "/hasCard"), body: body, headers: {
      "Accept": "application/json",
      "content-type": "application/json"
    print(res.toString());
    if (res.statusCode == 200) {
      this.paymentModel = PaymentModel.fromJson(json.decode(res.body));
      return true;
    return false;
And in my Widget I want to check this value:
Widget build(BuildContext context) {
    var user = Provider.of<UserRepository>(context);
    if(user.hasCard())
      //do something
But I get an error message:
  Conditions must have a static type of 'bool'.dart(non_bool_condition)
Since it is a Widget type I cannot use async here. What could be the way to solve this?
You can use a FutureBuilder, it will build the widget according to the future value, which will be null until the future is completed. Here is an example.
FutureBuilder(
  future: hasCard(),
  builder: (context, snapshot) {
    if (snapshot.data == null)
      return Container(
          width: 20,
          height: 20,
          child: CircularProgressIndicator());
    if (snapshot.data)
      return Icon(
        Icons.check,
        color: Colors.green,
      return Icon(
        Icons.cancel,
        color: Colors.red,
Well not only for a Future<bool> for any other future you can use the FutureBuilder where the future is what returns you the type of future and snapshot is the data recieved from it.
  FutureBuilder(
      future: hasCard(),
      builder: (context, snapshot) {
        if (snapshot.data != null){
          print(snapshot.data)}
        else{
         print("returned data is null!")}  
and I would suggest assigning a default value to your bool.
good luck!
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