[英]How to update value in Firebase with childByAutoId?
When I create objects in Firebase, I use childByAutoId. 当我在Firebase中创建对象时,我使用childByAutoId。 How can I update these specific objects later?
我以后如何更新这些特定对象? I'm having trouble obtaining the value of the key Firebase automatically updates.
我无法获得关键Firebase自动更新的价值。 Snapshot.key just returns "users".
Snapshot.key只返回“用户”。 Here's my JSON structure:
这是我的JSON结构:
{
"users" : {
"-KQaU9lVcUYzIo52LgmN" : {
"device" : "e456f740-023e-440a"
"name: "Test"
}
},
How can I get the -KQaU9lVcUYzIo52LgmN
key? 如何获得
-KQaU9lVcUYzIo52LgmN
键? I want to update the device child. 我想更新设备子。 Here's what I have so far.
这是我到目前为止所拥有的。 It currently creates a completely separate snapshot with a single child.
它目前使用单个子项创建一个完全独立的快照。
self.rootRef.child("users").queryOrdered(byChild: "name").queryEqual(toValue: self.currentUser).observeSingleEvent(of: .value, with: { (snapshot) in
let key = self.rootRef.child("users").childByAutoId().key
let childValues = ["device": device]
self.rootRef.child("users").child(key).updateChildValues(childValues)
Edit: device is a string set further up in the code. 编辑:设备是代码中进一步设置的字符串。 Not defined in this scope (to make it easier to read for this question).
未在此范围内定义(以便更容易阅读此问题)。
When you get Snapshot.key, it returns "users" because that is the overall key for your snapshot. 当您获得Snapshot.key时,它将返回“users”,因为这是您的快照的总体密钥。 Everything inside of "users" in your snapshot is considered the value.
快照中“用户”内的所有内容都被视为值。
You need to iterate over the child layers to dig down to "device". 您需要迭代子图层以挖掘“设备”。
Try this: 尝试这个:
rootRef.child("users").observeSingleEventOfType(.Value, withBlock: { (snapshot) in
if let result = snapshot.children.allObjects as? [FIRDataSnapshot] {
for child in result {
var userKey = child.key as! String
if(userKey == userKeyYouWantToUpdateDeviceFor){
rootRef.child("users").child(userKey).child("device").setValue(device)
}
}
}
})
This code will do the following: 此代码将执行以下操作:
'users'
). 'users'
)。 'result'
. 'result'
。 "-KQaU9lVcUYzIo52LgmN"
, it will find it on the first iteration in your example code you posted). "-KQaU9lVcUYzIo52LgmN"
,它将在您发布的示例代码的第一次迭代中找到它)。 rootRef.child("users").child(userKey).child("device").setValue(device)
. rootRef.child("users").child(userKey).child("device").setValue(device)
行rootRef.child("users").child(userKey).child("device").setValue(device)
该密钥内的设备的值rootRef.child("users").child(userKey).child("device").setValue(device)
。 Of course, you will need to store all your user keys when you make them. 当然,您需要在制作用户密钥时存储它们。 You can maybe use SharedPreferences on the device for this, but if it gets cleared for any reason then that data will just be sitting there.
您可以在设备上使用SharedPreferences,但如果它因任何原因被清除,那么该数据将只是坐在那里。 You could also store it on internal storage for your app, but SharedPreferences is what I would use.
您也可以将它存储在应用程序的内部存储中,但我会使用SharedPreferences。
Hope this helps! 希望这可以帮助!
snapshot
has a property key
which is snapshot
有一个属性key
The key of the location that generated this FIRDataSnapshot.
生成此FIRDataSnapshot的位置的关键字。
And as you can see you are getting one (snapshot) by calling observeSingleEvent(of: .value, with: { (snapshot)...
正如你所看到的,通过调用
observeSingleEvent(of: .value, with: { (snapshot)...
来获得一个observeSingleEvent(of: .value, with: { (snapshot)...
so instead of let key = self.rootRef.child("users").childByAutoId().key
所以代替
let key = self.rootRef.child("users").childByAutoId().key
try to call let key = snapshot.key
尝试调用
let key = snapshot.key
childByAutoId().key
always generates new unique key based on timestamp, that's why you are creating new child, not updating the one you want childByAutoId().key
总是根据时间戳生成新的唯一键,这就是你创建新子的原因,而不是更新你想要的那个
Hope that works 希望有效
I adapted Ryan's answer to my own issue (kinda similar) and figured out a way to update your device ID directly without needed to know/store the AutoID key generated by Firebase : 我根据自己的问题(有点类似)调整了Ryan的答案,并想出了一种直接更新设备ID的方法,而无需知道/存储Firebase生成的AutoID密钥:
reference = Database.database().reference().child("users")
reference.observeSingleEvent(of: .value, with: { (snapshot) in
if let result = snapshot.children.allObjects as? [DataSnapshot] {
for child in result {
if child.childSnapshot(forPath: "device").value as? String == self.yourDeviceIDVariable {
print("### Device exists in Firebase at key = \(child.key)")
let childKey = child.key
self.reference.child(childKey).child("device").setValue(yourNewDeviceID)
}
}
}
})
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