当我尝试获取不存在的Firestore文档时，我的应用程序崩溃
Firestore文档说我应该得到一个空文档，而不是终端错误 https://firebase.google.com/docs/firestore/query-data/get-data
注意：如果docRef引用的位置没有文档， 生成的文档将为null。
我复制错误的代码如下。对于此次运行，只需使用两个简单按钮即可。第一个按钮（doReadDeepDocument）读取文档以确保它确实存在。第二个按钮（doDeleteDeepDocument）删除文档。请注意，该文档位于子集合中。
import UIKit
import Firestore
class ViewController: UIViewController {
var listenerFriends: FIRListenerRegistration?
@IBAction func doReadDeepDocument(_ sender: Any) {
print("\nDo Read")
let db = Firestore.firestore()
let docRef = db.collection("basic").document("c9qjeO2uSXhPWejYIQ5H").collection("deep").document("4ZgsZJ1xQ3NfDj6BTv3H")
docRef.getDocument { (document, error) in
if error != nil {
print("Error reading the document \(error.debugDescription)")
return
}
print("Inside read completion")
if let document = document {
print("SUCCESS GET Document data: \(document.data())")
} else {
print("ERROR Document does not exist")
}
}
}
@IBAction func doDeleteDeepDocument(_ sender: Any) {
print("\nDo Delete")
let db = Firestore.firestore()
let docRef = db.collection("basic").document("c9qjeO2uSXhPWejYIQ5H").collection("deep").document("4ZgsZJ1xQ3NfDj6BTv3H")
docRef.delete() { err in
print("Inside delete completion")
if let err = err {
print("Error removing document: \(err)")
} else {
print("Document successfully removed!")
}
}
}
@IBAction func doBasicWrite(_ sender: Any) {
var values = [String : Any]()
values["fld1"] = 1
values["fld2"] = "Two"
let db = Firestore.firestore()
db.collection("basic").document().setData(values) { (error) in
if error != nil {
print("basic write failed \(error.debugDescription)")
} else {
print("basic write success")
}
}
}
@IBAction func doReadBasicSet(_ sender: Any) {
let db = Firestore.firestore()
db.collection("basic").getDocuments() { (querySnapshot, err) in
if let err = err {
print("Error getting documents: \(err)")
} else {
print("Success getting documents")
for document in querySnapshot!.documents {
print("\(document.documentID) => \(document.data())")
}
}
}
}
@IBAction func doDeepWrite(_ sender: Any) {
var values = [String : Any]()
values["fldA"] = 1
values["fldB"] = "BBB"
let db = Firestore.firestore()
db.collection("basic").document("c9qjeO2uSXhPWejYIQ5H").collection("deep").document().setData(values) { (error) in
if error != nil {
print("deep write failed \(error.debugDescription)")
} else {
print("deep write success")
}
}
}
@IBAction func doReadDeepSet(_ sender: Any) {
let db = Firestore.firestore()
db.collection("basic").document("c9qjeO2uSXhPWejYIQ5H").collection("deep").getDocuments() { (querySnapshot, err) in
if let err = err {
print("Error getting documents: \(err)")
} else {
print("Success getting documents")
for document in querySnapshot!.documents {
print("\(document.documentID) => \(document.data())")
}
}
}
}
@IBAction func doStartListen(_ sender: Any) {
// Get all my friends
let db = Firestore.firestore()
let deepRef = db.collection("basic").document("c9qjeO2uSXhPWejYIQ5H").collection("deep")
// start listener
listenerFriends = deepRef.addSnapshotListener { querySnapshot, error in
guard let snapshot = querySnapshot else {
print("Error fetching snapshots: \(error!)")
return
}
snapshot.documentChanges.forEach { diff in
if (diff.type == .added) {
self.watchFriend_Added( diff : diff )
}
if (diff.type == .modified) {
// could be a case where it is marked as 'modified' but is really 'new'
// reletive to the start of the listener
// e.g. it was recently changed but prior to the start of the listen.
self.watchFriend_Modified( diff : diff )
}
if (diff.type == .removed) {
self.watchFriend_Removed( diff : diff )
}
}
}
}
func watchFriend_Added( diff : DocumentChange) {
print("\nNew friend: \(diff.document.data())")
print("ID: \(diff.document.documentID)")
}
func watchFriend_Modified( diff : DocumentChange) {
print("\nModified friend: \(diff.document.data())")
print("ID: \(diff.document.documentID)")
}
func watchFriend_Removed( diff : DocumentChange) {
print("\nRemoved friend: \(diff.document.data())")
print("ID: \(diff.document.documentID)")
}
@IBAction func doStopListen(_ sender: Any) {
// Stop listening for changes
if listenerFriends != nil {
listenerFriends?.remove()
}
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
-
以下是调试控制台结果。您可以看到成功读取（按下读取按钮）。这确认了数据最初存在且路径正确。然后您会看到成功删除（按下删除按钮）。然后我再次推读，应用程序崩溃。
Do Read
Inside read completion
SUCCESS GET Document data: ["fldB": EEE, "fldA": 1]
Do Delete
Inside delete completion
Document successfully removed!
Do Read
Inside read completion
2018-03-03 12:09:44.471079-0800 testfs[32914:2379972] *** Terminating app due to uncaught exception 'NonExistentDocumentException', reason: 'Document '<FSTDocumentKey: basic/c9qjeO2uSXhPWejYIQ5H/deep/4ZgsZJ1xQ3NfDj6BTv3H>' doesn't exist. Check document.exists to make sure the document exists before calling document.data.'
*** First throw call stack:
(
0 CoreFoundation 0x000000010dce112b __exceptionPreprocess + 171
1 libobjc.A.dylib 0x000000010ce28f41 objc_exception_throw + 48
2 testfs 0x000000010aaacf0b -[FIRDocumentSnapshot objectForKeyedSubscript:] + 0
3 testfs 0x000000010a9ddce4 _T06testfs14ViewControllerC18doReadDeepDocumentyypFySo0G8SnapshotCSg_s5Error_pSgtcfU_ + 1188
4 testfs 0x000000010a9ddfbc _T0So16DocumentSnapshotCSgs5Error_pSgIxxx_ACSo7NSErrorCSgIyByy_TR + 124
5 testfs 0x000000010aaac2bb __50-[FIRDocumentReference getDocumentWithCompletion:]_block_invoke + 357
6 testfs 0x000000010aaac878 __72-[FIRDocumentReference addSnapshotListenerInternalWithOptions:listener:]_block_invoke + 305
7 libdispatch.dylib 0x0000000110f352f7 _dispatch_call_block_and_release + 12
8 libdispatch.dylib 0x0000000110f3633d _dispatch_client_callout + 8
9 libdispatch.dylib 0x0000000110f415f9 _dispatch_main_queue_callback_4CF + 628
10 CoreFoundation 0x000000010dca3e39 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 9
11 CoreFoundation 0x000000010dc68462 __CFRunLoopRun + 2402
12 CoreFoundation 0x000000010dc67889 CFRunLoopRunSpecific + 409
13 GraphicsServices 0x000000011423e9c6 GSEventRunModal + 62
14 UIKit 0x000000010e15f5d6 UIApplicationMain + 159
15 testfs 0x000000010a9e54f7 main + 55
16 libdyld.dylib 0x0000000110fb2d81 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
我是否需要捕获GetDocument（）在任何地方使用的致命错误，或者这是一个将被修复的错误。或者，其他一些建议？
答案 0 :(得分：2)
不在Xcode，但以下情况应该有效：
if let document = document, document.exists {
print("SUCCESS GET Document data: \(document.data())")
} else {