问题
Is there a way to implement back pagination with firestore? I am struggling to implement pagination with firestore, and there are limited firestore queries for it. Forward pagination can be made by startAt and limit method, that is ok. But back pagination can't be easily done, because we only have endBefore, and endAt method, and how can we get last n elements from given document? I know realtime database have method limitToLast. Is there any query like this for firestore? (Also I need to implement multiple sorting, so getting last documents with "ASC" or "DESC" sorting will not work) Help much appreciated.
Thanks!
回答1:
The equivalent to the limitToLast(...) operation from the Firebase Realtime Database in Cloud Firestore is to order the data descending (which is possible in Firestore) and then just limit(...). If you're having problems implement this, update your question to show what you've done.
I agree that this is a sub-optimal API for back-pagination, since you're receiving the items in reverse order.
回答2:
I was running into this same issue, and not understanding why using limit with endAt wasn't returning the results I desired. I was attempting to implement a list in which you could paginate in both directions, first forward and then backward back to the start of the list.
To remedy the situation I decided to just cache the startAfter DocumentSnapshot for each page so that one can move both directions, in this way I never have to use endAt. The only time this will become an issue is if the collection of documents shifts or changes while the user is on a page other than the first page, but by returning to the first page it will reset to the beginning of the collection.
来源：https://stackoverflow.com/questions/48342525/firestore-pagination-is-there-any-query-compatible-with-firebases-limittolast