我正在嘗試使用 Firebase Firestore startAfter()和limit()查詢方法實現分頁系統。第一個查詢成功返回，但第二個查詢返回空快照。這是我的getNextPage()方法：fun getNextPage(paginationSize : Long) : TrendingRepository {database.collection("app") .document("data") .collection("offers") .orderBy("discount") .startAfter(lastVisible) .limit(paginationSize) .get().addOnSuccessListener { snapshot -> Log.i("TrendingRepo", "pagination size : $paginationSize") val newList = ArrayList<Offer>() if (!snapshot.isEmpty) { lastVisible = snapshot.documents[snapshot.size() - 1] } for (document in snapshot) { val item = document.toObject(Offer::class.java) newList.add(item) Log.i("TrendingRepo", "at position: ${newList.indexOf(item)} got item: ${item.id}") } successListener?.onSuccess(newList) }.addOnFailureListener { failureListener?.onFailure(it.localizedMessage) }return this}這是我的 Logcat：TrendingRepo: pagination size : 48 // 第一次嘗試TrendingRepo：在位置：0 得到項目：0pqcRzSd06WWlNNmcoluTrendingRepo：在位置：1 得到了項目：7I7wiSYt5yEBWwN08bqJ...TrendingRepo：在位置：45 得到項目：4B3dEPhFLqhKrYpLWYE7TrendingRepo：在位置：46 得到項目：4ddLqiGe8ReXW8SKq2Q6TrendingRepo：在位置：47 得到項目：4uVnnGNAmKvGUUHcV01nTrendingRepo: pagination size : 48 // 第二次嘗試//不再記錄，數據為空
1 回答
qq_笑_17
TA貢獻1818條經驗 獲得超7個贊
可能存在項目小于分頁大小的情況所以這里是代碼
private var lastVisible: DocumentSnapshot? = null
private var isLastPage: Boolean = false
private var isDocEmpty: Boolean = false
var ref: Task<QuerySnapshot>? = null
if (lastVisible != null) {
ref = database.collection("app").document("data").collection("offers").orderBy("discount").startAfter(lastVisible).limit(paginationSize).get()
} else {
ref = database.collection("app").document("data").collection("offers").orderBy("discount").limit(paginationSize).get()
}
ref.addOnSuccessListener { documents ->
hideProgress()
isDocEmpty = documents.isEmpty
if (!isDocEmpty) {
lastVisible = documents.last()
isLastPage = documents.size() < paginationSize
}
isLoading = false
}
.addOnFailureListener { exception ->
Log.w("TAG", "Error getting documents: ", exception)
isLoading = false
hideProgress()
}
我希望這會幫助你。
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