How to "await" non-future variable? - dart

Question

I have DocumentReference locationDocumentRef; in my state.
I'm changing locationDocumentRef based on the references, whether I gather by querying or by adding new document.
So I have this function to check the documents, if there is one set its reference to the locationDocumentRef, or add a new one and set its ref to the locationDocumentRef. I'm resetting its value everytime by setting it to null, since I didn't want to get previous result. But it prints null.
So my question is, how can I resolve them and get the value? I think I'm resolving too early in my code, so I can't await a non-future value. How can I fix it?
void firestoreCheckAndPush() async {
setState(() {
locationDocumentRef = null;
});
bool nameExists = await doesNameAlreadyExist(placeDetail.name);
if (nameExists) {
print('name exist');
} else {
print('name will be pushed on firestore');
pushNameToFirestore(placeDetail);
}
var resolvedRef = await locationDocumentRef;
print(resolvedRef.documentID); // I get null here
}
These are the functions that I have used
Future<bool> doesNameAlreadyExist(String name) async {
QuerySnapshot queryDb = await Firestore.instance
.collection('locations')
.where("city", isEqualTo: '${name}')
.limit(1)
.getDocuments();
if (queryDb.documents.length == 1) {
setState(() {
locationDocumentRef = queryDb.documents[0].reference;
});
return true;
} else {
return false;
}
}
And the other
void pushNameToFirestore(PlaceDetails pd) async {
DocumentReference justAddedRef =
await Firestore.instance.collection('locations').add(<String, String>{
'city': '${pd.name}',
'image': '${buildPhotoURL(pd.photos[0].photoReference)}',
});
setState(() {
locationDocumentRef = justAddedRef;
});
}

Answer 1

there is two mistakes i saw first here
var resolvedRef = await locationDocumentRef;
why you await for locationDocumentRef,
second you dont wait for pushNameToFirestore(PlaceDetails pd) firestoreCheckAndPush() function which is weird since pushNameToFirestore(String) is sync and this means you wouldnt wait for it to finish so if you are adding a new name it would print null.
correct me if i am wrong.
you can find more about sync and future here https://www.dartlang.org/tutorials/language/futures
look at the graph at the middle of the page

Answer 2

Try this
Future<List<DocumentSnapshot>> doesNameAlreadyExist(String name) async {
QuerySnapshot data = await Firestore.instance
.collection('locations')
.where("city", isEqualTo: name)
.limit(1)
.getDocuments();
return data.documents;
}
void firestoreCheckAndPush() async {
var data = await doesNameAlreadyExist('yourname');
if (data.length > 0) {
print('name exist');;
print('Document id '+ data[0].documentID);
} else {
print('name will be pushed on firestore');
}
}

Answer 3

Take a look into following code.
void firestoreCheckAndPush() async {
DocumentReference documentReference;
var data = await doesNameAlreadyExist('yourname');
var dataRef = await doesNameAlreadyExist('yourname');
if (data.length > 0) {
print('name exist');
documentReference = dataRef[0].reference;
print('Document id ' + data[0].documentID);
documentReference = dataRef[0].reference;
print('Document reference ');
print(documentReference);
} else {
print('name will be pushed on firestore');
}
}