Exclude documents from firebase query using date - firebase

Question

I have a model of posts which have a post time and expire time like so
class BuyerPost{
..some other properties...
final Timestamp postTime;
final Timestamp expireTime;
My intended outcome is that the expired posts will not be included in my query. If i could delete them from the database automatically the better but I would also work with just excluding them from my query.
I have tried to use the endAt and orderBy to achieve it but it failed
Stream <List<BuyerPost>> get sellerBuyerPosts {
try {
return buyerPostCollection.where('status',isEqualTo: 'available')
.orderBy('expireTime',descending: true)
.endAt([Timestamp.now()])
.snapshots()
.map(yieldSellerBuyerPosts);
}catch(e){
print(e.toString());
return null;
}
}
I also tried filtering on the client side but i got a type operator error because <,> is not available for time stamp
List<BuyerPost> yieldSellerBuyerPosts(QuerySnapshot snapshot) {
try {
return snapshot.documents.map((doc) {
return BuyerPost(
...some properties here...
postTime: doc.data['postTime']?? Timestamp(0,0),
expireTime: doc.data['expireTime']?? Timestamp(0,0),
);
}).where((post) =>
post.expireTime>Timestamp.now()
).toList();
}catch(e){
print(e.toString());
return null;
}
}
Am i using the wrong method or have i just made a slight error somewhere.

Answer 1

Don't use endAt in this query. That's for pagination, which you're not using here. If you want to constrain the range of values for a field, use another "where" filter to specify the range of values for that field:
return buyerPostCollection
.where('status', isEqualTo: 'available')
.where('expireTime', isLessThan: Timestamp.now())
.orderBy('expireTime', descending: true)
.snapshots()

Answer 2

The first method actually worked the only issue is that it does not work along with the stream. The only way you will see an update in post queries is with change of widget state, and you will find expired posts disappeared.