See the print statement down below. It never executes.
Future<void> populate() async {
final userId = FirebaseAuth.instance.currentUser!.uid;
final db = FirebaseFirestore.instance;
// Get list of ids of parties use swiped on.
var snapshot1 = await db
.collection("partiers_swipes")
.where('userId', isEqualTo: userId)
.get();
var partyIdsUserSwipesOn = [];
if (snapshot1.size > 0) {
snapshot1.docs.forEach((element) {
partyIdsUserSwipesOn.add(element.data()['partyId']);
});
}
var snapshot2 = await db
.collection("parties")
.where(FieldPath.documentId, whereNotIn: partyIdsUserSwipesOn)
.get();
print('This never executes');
}
The whereNotIn argument is not supported by the where clause. This crashes the function.
Related
I have a collection ads that contains a DocumentReference as ownerId.
With the code below, I am able to fetch the 10 most recent ads as aList<Ad>:
/// Returns a list of ads of the given [category]
static Future<List<ClassifiedAd>> getFromCategory(
ClassifiedAdCategory category,
{int max = 10}) async {
return FirebaseFirestore.instance
.collection('ads')
.where('category', isEqualTo: category.name)
.orderBy('creationDate', descending: true)
.limit(max)
.get()
.then((snapshot) {
return snapshot.docs.map((doc) {
final data = doc.data();
return Ad.fromMap(data);
}).toList();
});
But now I'd like to fetch the owner (collection users) from the DocumentReference I was talking about above. But I am a but puzzled about how to do that.
My modified code below does not compile:
The return type 'List' isn't a 'FutureOr<List>', as required by the closure's context.
/// Returns a list of ads of the given [category]
static Future<List<ClassifiedAd>> getFromCategory(
ClassifiedAdCategory category,
{int max = 10}) async {
return FirebaseFirestore.instance
.collection('ads')
.where('category', isEqualTo: category.name)
.orderBy('creationDate', descending: true)
.limit(max)
.get()
.then((snapshot) {
// <<<< Error starts right here down to the removeWhere()
return snapshot.docs.map((doc) {
final data = doc.data();
final DocumentReference docRef = data["ownerId"];
return docRef.get().<ClassifiedAd?>then((snapshot) {
if (snapshot.exists) {
return ClassifiedAd.fromMap(data);
}
return null;
});
}).toList()
// Don't take into account potential nulls
..removeWhere((a) => a == null);
});
How should I do that?
I would say that the wrong thing that you're doing is you're trying to get a snapshot asynchronously inside the map() method which is synchronous, for such cases like yours, I recommend using await/async and to not return anything until you guarantee that you got it, try this:
static Future<List<ClassifiedAd>> getFromCategory(
ClassifiedAdCategory category,
{int max = 10}) async {
final snapshot = await FirebaseFirestore.instance
.collection('ads')
.where('category', isEqualTo: category.name)
.orderBy('creationDate', descending: true)
.limit(max)
.get();
List<ClassifiedAd> result = [];
for (int index = 0; index < snapshot.docs.length; index++) {
final doc = snapshot.docs[index];
final data = doc.data();
final DocumentReference docRef = data["ownerId"];
final docOwnerSnapshot = await docRef.get();
if (docOwnerSnapshot.exists) {
result.add(ClassifiedAd.fromMap(data));
}
}
return result;
}
I am creating like system and i want to get likeCount from firebase which i created.
It's collecting it but returns null,
here is my code:
String? getLikecount(tresc) {
String? likeCount;
FirebaseFirestore.instance
.collection('Posty')
.where('Tresc', isEqualTo: tresc)
.get()
.then((value) => value.docs.forEach((element) async {
var id = element.id;
final value = await FirebaseFirestore.instance.collection('Posty').doc(id).get();
likeCount = value.data()!['likeCount'].toString();
print(likeCount);
}));
print(likeCount);
return likeCount;
}
and here is console output:
Data is loaded from Firestore (and most modern cloud APIs) asynchronously, because it may needs to come from the network and we can't block your code (and your users) while waiting for it.
If we change the print statements a bit, and format the code, it'll be much easier to see what's going on:
String? getLikecount(tresc) {
String? likeCount;
FirebaseFirestore.instance
.collection('Posty')
.where('Tresc', isEqualTo: tresc)
.get()
.then((value) => value.docs.forEach((element) async {
var id = element.id;
final value = await FirebaseFirestore.instance
.collection('Posty')
.doc(id)
.get();
likeCount = value.data()!['likeCount'].toString();
print('In then: $likeCount');
}));
print('After then: $likeCount');
return likeCount;
}
If you run this, you'll see it outputs:
After then: null
In then: 0
This is probably not what you expected, but it explains perfectly why you don't get a result. By the time your return likeCount runs, the likeCount = value.data()!['likeCount'].toString() hasn't executed yet.
The solution is always the same: any code that needs the data from the database has to be inside the then handler, be called from there, or be otherwise synchronized.
In Flutter it is most common to use async and await for this. The key thing to realize is that you can't return something now that hasn't been loaded yet. With async/await you function becomes:
Future<String?> getLikecount(tresc) {
String? likeCount;
var value = await FirebaseFirestore.instance
.collection('Posty')
.where('Tresc', isEqualTo: tresc)
.get();
for (var doc in value.docs) {
var id = element.id;
final value = await FirebaseFirestore.instance
.collection('Posty')
.doc(id)
.get();
likeCount = value.data()!['likeCount'].toString();
print('In then: $likeCount');
}));
print('After then: $likeCount');
return likeCount;
}
Now your code returns a Future<String?> so a value that at some point will hold the string. When calling getLikecount you will now need to use then or await to handle the Future, and if you want to show the count in the UI you will have to store it in the State of a StatefulWidget.
This is firestore database structure. I'm trying to call these data in my flutter application. but I only get value upto document which is chatroom/9000. But i want collection of document 9000. How do i call it?
This is how i called query
await _firestore .collection('chatroom') .doc(UUID) .get() .then((value) { });
Future<dynamic> getValues() async{
var _chatroom =await _firestore .collection('chatroom').get((value)async{
if(value !=null ){
for(var index = 0 ; index< value.documents.length ; index++ )
var _chatitem = await _firestore .collection('chatroom')
.doc(value.value.documents[index].documentId) .get() .then((value) {
// Do what you Want
})
}
});
}
trying to fetch results within a for loop , but for loop doesn't wait for firestore results.tried forEach as well before .
Future<bool> checkIfNewMessages() async{
bool hasNewMessage=false;
QuerySnapshot _myDoc = await Firestore.instance.collection('PropMap')
.orderBy('ProJoiningDate')
.where('TenId', isEqualTo: globals.memberAuthId)
.getDocuments();
List<DocumentSnapshot> properties = _myDoc.documents;
if(properties.length>0)
for(final property in properties) {
//properties.forEach((property) { //tried forEach() as well
String propid= property.data['PropertyId'];
if(property.data['LastVisitTime']!=null) {
DateTime tenantsLastPropVisitTime = property.data['LastVisitTime'].toDate();
getLastPropertyChatTime(propid).then((latestPropChatTime) { //This 'then' seems not working
print('LAST chat date is ${latestPropChatTime}');
if (latestPropChatTime.isAfter(tenantsLastPropVisitTime)) //This means he has not seen new messages , lets notify him
{
hasNewMessage= true;
}
});
}
};
return hasNewMessage;
}
And these are the fetch methods,when the breakpoint is at getDocuments() of getTheLastChat() the control just jumps back to for loop again without waiting for results .
Future getTheLastChat(propId) async {
QuerySnapshot _myDoc =await Firestore.instance.collection('Chats').orderBy('ChatDate', descending: true)
.where('PropertyId', isEqualTo: propId)
.limit(1)
.getDocuments();
List<DocumentSnapshot> tenants = _myDoc.documents;
return tenants;
}
Future<DateTime> getLastPropertyChatTime(propId) async {
DateTime lastChatTime= DateTime.now().add(Duration(days:-365));
var lastChatTimeDocs = await getTheLastChat(propId);
lastChatTime=lastChatTimeDocs.length>0?lastChatTimeDocs[0].data["ChatDate"].toDate():DateTime.now().add(Duration(days:-365));
return lastChatTime;
}
You can use the Future.forEach to achieve your requirement
Future<void> buildData(AsyncSnapshot snapshot) async {
await Future.forEach(snapshot.data.documents, (element) {
employees.add(Employee.fromSnapshot(element));
});
}
The following code works fine, because it return only a simple list, but in some cases that I need to do nested Firebase calls, I can't make things happen in the right order, and the main return statement comes incomplete. What can I do to improve my Future Asynchronous Calls?
Future<List<MyNotification>> getNotifications() async {
var uid = await FirebaseAuth.instance.currentUser();
List<MyNotification> tempNots = await Firestore.instance
.collection("notifications")
.where("targetUsers", arrayContains: uid.uid)
.getDocuments()
.then((x) {
List<MyNotification> tempTempNots = [];
if (x.documents.isNotEmpty) {
for (var not in x.documents) {
tempTempNots.add(MyNotification.fromMap(not));
}
}
return tempTempNots = [];
});
return tempNots;
}
The most important thing; don't use then inside your async functions. I modified your code like this;
Future<List<MyNotification>> getNotifications() async {
// Using the type definition is better.
FirebaseUser user = await FirebaseAuth.instance.currentUser();
// The return type of getDocuments is a QuerySnapshot
QuerySnapshot querySnapshot = await Firestore.instance
.collection("notifications")
.where("targetUsers", arrayContains: user.uid)
.getDocuments();
List<MyNotification> tempTempNots = [];
if (querySnapshot.documents.isNotEmpty) {
for (DocumentSnapshot not in querySnapshot.documents) {
tempTempNots.add(MyNotification.fromMap(not));
}
}
return tempTempNots;
}