Question 78262 in Flutter Question posted in
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If my async function successfully completed, is this the correct way to then do something else? – Flutter

I have the following code. The idea is that it will create a record in the groups collection. If successful, then it should create a record in a different collection – the groups_UID collection. Is this the correct way to do this? I feel like it might be wrong because async/await are normally used separately from .then(), right? Or maybe I’m just misremembering something here.

await docRef.set({
      'adminUID': currentUID,
      'adminUsername': currentUsername,
      'createDate': timestamp,
      'groupID': groupID,
      'groupName': groupName,
    }).then((value) async {
      print('##MyApp## database createGroupFS groups record added');

      CollectionReference groupsUIDCollection = firestore.collection('groups_' + currentUID);
      final groupsUIDDocRef = groupsUIDCollection.doc();

      await groupsUIDDocRef.set({
        'adminUID': currentUID,
        'adminUsername': currentUsername,
        'createDate': timestamp,
        'groupID': groupID,
        'groupName': groupName,
      }).then((value) {
        print('##MyApp## database createGroupFS groups_UID record added');
        returnVal = groupID;
      }).catchError((error) {
        print('##MyApp## database createGroupFS groups_UID ERROR: ' + error.toString());
        returnVal = '';
      });
    }).catchError((error) {
      print('##MyApp## database createGroupFS groups ERROR: ' + error.toString());
      returnVal = '';
    });
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2

Answers


  1. 0

    You should either use one or another. I prefer using async/await with try/catch because I find it more readable. So in your example solution would be:

    try {
  // if it fails it goes to the catch part
  final res = await docRef.set({
    'adminUID': currentUID,
    'adminUsername': currentUsername,
    'createDate': timestamp,
    'groupID': groupID,
    'groupName': groupName,
  });
  // it will continue going on success
  print('##MyApp## database createGroupFS groups record added');

  CollectionReference groupsUIDCollection =
      firestore.collection('groups_' + currentUID);
  final groupsUIDDocRef = groupsUIDCollection.doc();

  try {
    // same thing here
    final res2 = await groupsUIDDocRef.set({
      'adminUID': currentUID,
      'adminUsername': currentUsername,
      'createDate': timestamp,
      'groupID': groupID,
      'groupName': groupName,
    });
    // success
    print('##MyApp## database createGroupFS groups_UID record added');
    returnVal = groupID;
  } catch (error) {
    // error happened on groupsUIDDocRef.set
    print('##MyApp## database createGroupFS groups_UID ERROR: ' +
        error.toString());
    returnVal = '';
  }
} catch (error) {
  // error happened on docRef.set
  print(
      '##MyApp## database createGroupFS groups ERROR: ' + error.toString());
  returnVal = '';
}
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  2. 0

    you should use try/catch as it will give you more flexibility when the awaited function throws error.

    the syntax should be,

    try{
var result= await someFunction();
//perform action 
}catch(e,stacktrace){
//handle error
}
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