I have a document collection called posts_favorites, which stores the reference to all the Posts that a user has bookmarked. The posts_favorites collection look as follows:
I have created a Stream to get all posts references that belong to a specific user, then I want to get the Post documents from the posts collection using the posts references.
I created a Stream to produce the data I need, but I am not getting any data returned from my Stream. Here is my code for the Stream:
Stream<List<PostsRecord>> getFavoritePostsStream() async* {
List<PostsRecord> myList = [];
await FirebaseFirestore.instance
.collection("posts_favorites")
.where("user", isEqualTo: currentUserReference)
.get()
.then((favoriteList) {
favoriteList.docs.forEach((element) async {
String documentPath = element['post'].toString();
var start = documentPath.indexOf("/");
var end = documentPath.indexOf(")");
var documentRef = documentPath.substring(start+1, end);
//DocumentReference docRef = FirebaseFirestore.instance.doc(documentPath);
DocumentReference docRef = FirebaseFirestore.instance.collection('posts').doc(documentRef);
await docRef.get().then((DocumentSnapshot documentSnapshot) async {
if (documentSnapshot.exists) {
print('Document exists on the database');
PostsRecord postsRecord = PostsRecord.getDocumentFromData(
documentSnapshot.data(), element['post']);
//return myList.add(postsRecord);
//print(postsRecord);
return postsRecord;
}
});
});
});
}
I know this function works because the commented code produces the Post Records that I expect to get from Firestore.
I am not sure how to get the Stream function to return data that I can use in the Stream.
Thank you
Related
In the code snippet below, how do I ensure that the senderID list gets populated before checking what the list contains?
I'm pulling data from firestore, storing it in a list, and then checking if it contains a particular key.
Stream<List<Group>> getChatGroups(String grpId) {
return firestore.collection('groups').snapshots().map((event) {
List<Group> groups = [];
List<String> senderIds = [];
for (var document in event.docs) {
var group = Group.fromMap(document.data());
firestore.collection('groups').doc(group.groupId).collection('chats').get().then((QuerySnapshot snapshot) {
snapshot.docs.forEach((DocumentSnapshot doc) {
var messageData = doc.data() as Map<String, dynamic>;
var messages = Message.fromMap(messageData);
var grId = doc.reference.parent.parent?.id;
//The values in SenderIds should be set before the function below is initiaited
senderIds.add(messages.senderId);
});
});
//This if function should initiate after getting set above
if (senderIds.contains(auth.currentUser!.uid)) {
groups.add(group);
}
}
return groups;
});
}
If you want senderIds.contains to be called only after all of your Futures have completed, build a List of those Futures and use Future.wait on that List. Something like:
var futures = <Future<void>>[];
for (var document in event.docs) {
// ...
futures.add(
firestore
.collection('groups')
.doc(group.groupId)
.collection('chats')
.get()
.then((QuerySnapshot snapshot) {
// ...
}),
);
}
await Future.wait(futures);
if (senderIds.contains(auth.currentUser!.uid)) {
// ...
}
Note that since the above code is asynchronous, you should also be using asyncMap instead of map.
I have a chat collection.
each document has an array with two user id's.
my goal is to get the chat that has both user sys id's
I tried running the following but I got an error because we cant use two 'arrayContains' in one query.
Is there any way to perform such query?
here is an image of the data structure
Future getChat({required List userIdsArr}) async {
var docId = '';
userIdsArr.sort((a, b) {
return a.compareTo(b);
});
var filter1 = userIdsArr[0];
var filter2 = userIdsArr[1];
await chat
.where(userIdsArrayColumn, arrayContains: userIdsArr[0])
.where(userIdsArrayColumn, arrayContains: userIdsArr[1])
.get()
.then((value) {
value.docs.forEach((element) {
docId = element.id;
});
});
return docId;
}
the goal is to get the chat that pertains to the users being passed in userIdsArr
this seems to work, is there a better way of doing this?
Future getChat({required List userIdsArr}) async {
var docId = '';
userIdsArr.sort((a, b) {
return a.compareTo(b);
});
await chat
.where(userIdsArrayColumn, arrayContains: userIdsArr[0])
// .where(userIdsArrayColumn, arrayContains: userIdsArr[1])
.get()
.then((value) {
value.docs.forEach((element) {
if (element[userIdsArrayColumn].contains(userIdsArr[1])) {
log('match found!');
docId = element.id;
}
});
});
return docId;
}
A query can only contain a single array-contains query.
To allow your query, you'll want to add an additional field to the document where you keep the pair of UIDs in a predictable (e.g. alphabetical) order. With such a field you can then use a query such as:
where("concatenated_uids", isEqualTo: userIdsArr[0]+"_"+ userIdsArr[1])
I am working on a chat app using Flutter and Firebase. I am new to Dart and so got stuck when I wanted to create a function which fetches (using await) a particular document from one collection (forums) and use an array property of the forum document to query and return a Stream from another collection (openMessages). The problem with my current solution is that it always returns an empty array. I am sure I am using the keywords or logic incorrectly. Can you please help me refactor my method.
Stream<List<ChatMessage>> getForumChatStream(String forumId) async* {
List<ChatMessage> messages = [];
var docSnap = await firestore.collection('forums').doc(forumId).get();
Forum forum = Forum.fromMap(docSnap.data()!);
firestore
.collection('openMessages')
.where('messageId', whereIn: forum.messageIds)
.orderBy('timeSent', descending: true)
.snapshots()
.map((event) {
for (var document in event.docs) {
messages.add(ChatMessage.fromMap(document.data()));
}
});
//print('LENGTH:'+messages.length.toString());
yield messages;}
You can use the following method.
Stream<List<ChatMessage>> getForumChatStream(String forumId) async* {
final firestore = FirebaseFirestore.instance;
List<ChatMessage> messages = [];
var docSnap = await firestore.collection('forums').doc(forumId).get();
Forum forum = Forum.fromMap(docSnap.data()!);
final result = firestore
.collection('openMessages')
.where('messageId', whereIn: forum.messageIds)
.orderBy('timeSent', descending: true)
.snapshots();
await for (final r in result) {
final docs = r.docs;
for (final document in docs) {
messages.add(ChatMessage.fromMap(document.data()));
yield messages;
}
}
}
Or
Stream<List<ChatMessage>> getForumChatStream(String forumId) async* {
final firestore = FirebaseFirestore.instance;
List<ChatMessage> messages = [];
var docSnap = await firestore.collection('forums').doc(forumId).get();
Forum forum = Forum.fromMap(docSnap.data()!);
yield* firestore
.collection('openMessages')
.where('messageId', whereIn: forum.messageIds)
.orderBy('timeSend', descending: true)
.snapshots()
.map((event) =>
event.docs.map((e) => ChatMessage.fromMap(e.data())).toList());
}
I want to get field value.
my code is..
void _checkNumner(String number) async {
final userRef = firestore.collection('users');
var documentSnapshot =
await userRef.where("number", isEqualTo: true).get().then((num) {
QuerySnapshot<Map<String, dynamic>> number = num;
print(number);
print("test");
});
print(documentSnapshot);
}
but my console is
how I get field number?
I want to load number values in all docs.
I'm so beginer. T.T
Please reply from the masters
Thank you
Firebase firestore is a NoSQL, document-oriented database. User Data is stored in documents which are organized into collection , i.e collection contains list of document. In simpler words we can say QuerySnapshot contains/provide group of DocumentSnapshot. more about firestore data model
Collection --> QuerySnapshot --> Group of DocumentSnapshot
Document --> DocumentSnapshot
1) Fetch from collection - QuerySnapshot
Here we'll get list of DocumentSnapshots, we can filter by using where commad
Future<void> checkNumber(int number) async {
final QuerySnapshot snapshot = await FirebaseFirestore.instance
.collection('users')
.where("number", isEqualTo: number)
.get();
snapshot.docs.isEmpty
? {
//TODO: your code here
debugPrint("no data found")
}
: {
for (DocumentSnapshot element in snapshot.docs)
{
//TODO: your code here
debugPrint("number is: ${element['number']}"),
debugPrint("name is: ${element['name']}"),
}
};
}
1) Fetch from document - DocumentSnapshot
To fetch data from document we require documentId, and we get a single documentSnapshot instead of multiple like in above way.
Future<void> checkNumberWithDocId() async {
const String docId = 'aaaa';
final DocumentSnapshot snapshot = await FirebaseFirestore.instance.collection('users').doc(docId).get();
snapshot.exists
? {
//TODO: your code here
debugPrint("no data found")
}
: {
//TODO: your code here
debugPrint("number is: ${snapshot['number']}"),
debugPrint("name is: ${snapshot['name']}"),
};
}
i have implemented this code for retrieving the messages of this room.
final messagesProvider = StreamProvider((ref) {
FirebaseFirestore db = FirebaseFirestore.instance;
var room = ref.watch(roomIdProvider);
print('room updated');
print('room is '+room);
final docRef = db
.collection("messages")
.where("chat_room_id",isEqualTo: room)
// .orderBy('created_at')
// .orderBy('created_at',descending: true)
;
print(docRef.orderBy("created_at").snapshots());
return docRef.snapshots();
});
i want to sort the data and have tried these two lines separately but not worked for me
.orderBy('created_at')
.orderBy('created_at',descending: true)
where created at is a timestamp field.
I added a new collection called "school", there're two items added inside the document.
I used my code, and it works. Could you please remove ".where" and try it again?
void getMessagesTest() async{
QuerySnapshot querySnapshot = await _firestore.collection('school').orderBy('age',descending: true).get();
final allData = querySnapshot.docs.map((doc) => doc.data()).toList();
print(allData);
}
Updated 20220616:
Updated 20220618:
Yes, you could chain where and orderBy together. Please see my code below.
Reference link => Using Where and Order by different fields in Firestore query
void getMessagesTest() async{
QuerySnapshot querySnapshot = await _firestore.collection('school').orderBy('age', descending: true).where('age', isGreaterThan: 17).get();
final allData = querySnapshot.docs.map((doc) => doc.data()).toList();
print(allData);
}