将方法转换为 FutureBuilder：Flutter

Question

I'm new to flutter. This is the method that I used to retrieve the data from firebase and I'm able to get the exact answer in the console. My question is how I can convert this code into future builder so I am able to read the data in my application.

void getUser() async {
  firestoreInstance.collection("User Data").get().then((querysnapshot) {
    querysnapshot.docs.forEach((result) {
      firestoreInstance
          .collection("User Data")
          .doc(result.id)
          .collection("bank")
          .where('account_username', isEqualTo: ownerData?.name2)
          .get()
          .then((query Snapshot) {
        querysnapshot.docs.forEach((result) {
            print (result["bank_name"]);
        });
      });
    });
  });
}

Answer 1

You should return the value from the query, not print it

Your function should look like this

Future<String> getUser() async {
  firestoreInstance.collection("User Data").get().then((querysnapshot) {
    querysnapshot.docs.forEach((result) {
      firestoreInstance
          .collection("User Data")
          .doc(result.id)
          .collection("bank")
          .where('account_username', isEqualTo: ownerData?.name2)
          .get()
          .then((query Snapshot) {
        querysnapshot.docs.forEach((result) {
            return result["bank_name"];
        });
      });
    });
  });
}

The Futurebuilder should look like this

 FutureBuilder<String>(
    future: getUser(), // async work
    builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
       switch (snapshot.connectionState) {
         case ConnectionState.waiting: return Text('Loading....');
         default:
           if (snapshot.hasError)
              return Text('Error: ${snapshot.error}');
           else
          return Text('Result: ${snapshot.data}');
        }