flutter await result always null

Question

This is my function

Future<Address> readAddress() async {
    database = FirebaseDatabase(app: app);

   await  database
        .reference()
        .child(table_name)
        .child(uid)
        .once()
        .then((DataSnapshot snapshot) {
      print("address_start");
      if (snapshot.value == null) {
        print("address_start_value_null");
        return null;
      } else {
         print("address_start_value_not_null");
        print(snapshot.value);
        Address a = Address().map(snapshot.value);
      return  a;
     // return a;
      }


    }).catchError((onError) {
      print(onError);
      return onError;
    });
  }

This is my function call

readAddress().then((address) {

        if (address != null) {
          print("address read seucssfully " + address.firstname);
        } else {
          print(
              "address read faield result is null $address"); // + address.toString());

        }
      }).catchError((onError) {
        print("error on read address");
      });

But here always it returns null.
What is wrong here?

message from readAddress() function

[dart] This function has a return type of 'Future', but doesn't end with a return statement. [missing_return]

I don't know to explain more StackOverflow showing this error message when in try to post this question "t looks like your post is mostly code; please add some more details. "

Solution

The problem with your function is that it's not returning a Future, but the Address object instead. I would rewrite your function like this to just return the Address object

 Future<Address> readAddress() async {
    try{
    database = FirebaseDatabase(app: app);

   DataSnapshot snapshot = await  database
        .reference()
        .child(table_name)
        .child(uid)
        .once();
    return Address().map(snapshot.value);
    }catch(e) {
      print(e);
      return(e);
    }
  }

With this, your function call can be just this:

Address address = readAddress();

Simple, isn't it? I have taken care all of the error handling inside the function.

Comments

[Noodles]

Is print("address_start_value_null") called?

[Midhilaj]

no, it is not called

[Midhilaj]

it contain value i checked

[Midhilaj]

address_start_value_not_null is called

[Vas]

I don't see how this would work as functions marked with async are supposed to return a Future

[dshukertjr]

@Vas You need the function to be async, because it contains await statement.

[Vas]

Right, but then the function return type has to be Future<Address>