如何处理 firestore 查询，因为我将快照结果作为 FIRQuerySnapshot`

Question

我在处理 firestore 查询时遇到问题，因为我的代码在这里

let wallpaperRef = Firestore.firestore().collection("wallpaper").order(by: "noOfDownloads", descending: true)

wallpaperRef.getDocuments(completion: { (snap, error) in
    if error == nil {
        print(snap)
    }

})

现在这个查询的输出是这样的

Optional(<FIRQuerySnapshot: 0x600000070640>)
Optional(<FIRQuerySnapshot: 0x600000070640>)
Optional(<FIRQuerySnapshot: 0x6000000705c0>)

我想获取此查询快照并获取任何初始化为可读形式的数据

Answer 1

如果您运行对集合进行查询，您得到的结果是 QuerySnapshot 包含（可能）多个文档。要获取每个文档，您需要循环遍历结果。来自 Firebase documentation on reading multiple documents:

db.collection("cities").whereField("capital", isEqualTo: true)
    .getDocuments() { (querySnapshot, err) in
        if let err = err {
            print("Error getting documents: \(err)")
        } else {
            for document in querySnapshot!.documents {
                print("\(document.documentID) => \(document.data())")
            }
        }
}

所以您的代码只是缺少来自 else 块的循环。类似于：

wallpaperRef.getDocuments(completion: { (snap, error) in
    if error == nil {
        print(snap)
    } else {
        for document in snap!.documents {
            print("\(document.documentID) => \(document.data())")
        }
    }
})

如何处理 firestore 查询，因为我将快照结果作为 FIRQuerySnapshot`

How to process firestore query as i am getting snapshot result as FIRQuerySnapshot`

querying

ios

firebase

swift4

google-cloud-firestore