我有Firebase数据库,每个用户都有自己的电子邮件和用户名。如何检查唯一用户名?我尝试这样做,但我的代码不能正常工作,因此不同的用户可以使用相同的用户名
usernameField.isHidden = false
let username:String = self.usernameField.text!
if (usernameField.text?.isEmpty == false){
ref.child("users").queryOrdered(byChild("username").queryEqual(toValue: username).observeSingleEvent(of: .value, with: { snapshot in
if snapshot.exists(){
print("username exist")
}else{
ref.root.child("users").child(userID).updateChildValues(["username": username])
}
})
}
我在Firebase中有点新手我为每个用户存储电子邮件和用户名,例如newUserReference.setValue(["username":String(), "email" : self.emailTextField.text!])
。在下一个视图中,用户可以在username
中键入usernameField.text
,此值将添加到Firebase数据库中。但是,如果下一个用户(用户2)将输入与之前用户相同的用户名,则必须将其阻止,因为用户名应该是唯一的
答案 0 :(得分:1)
如果您尝试在登录时存储用户的ID,请在收到成功的登录响应后执行此操作:
创建一个共享实例来存储ID
class userDataSource {
var id : String? // variable to store your users ID
static let sharedInstance = PageDataSource() // global access to this dataSource
private init() {}
}
成功登录后为id分配值
func getIDFromLogin() {
if let user = Auth.auth().currentUser {
print(user.uid)
userDataSource.sharedInstance.id = user.uid
}
}
然后你可以这样做来查看每个id:
ref.child("users").observeSingleEvent(of: .value, with: { snapshot in
if let snapshots = snapshot.children.allObjects as? [DataSnapshot] {
for snap in snapshots {
print(snap.key) // you can compare userDataSource.sharedInstance.id to this value
}
}
})
或者,如果您只是希望该用户的数据执行此操作:
ref.child("users").child(userDataSource.sharedInstance.id!).observeSingleEvent(of: .value, with: { snapshot in
if let snapshots = snapshot.children.allObjects as? [DataSnapshot] {
for snap in snapshots {
print(snap)
}
}
})
编辑以更准确地回答您的问题
这是一个更符合您问题的答案。我建议您首先向Firebase添加一个仅包含用户名的表,以及它们所属的.uid
。您需要首先阅读该表以确保没有其他人拥有该用户名,然后相应地更新表:
// This function will check through all of the usernames and return a true or false value in the completion handler
func checkUsernames(_ completion: @escaping(_ success: Bool) -> Void) {
ref.child("usernames").observeSingleEvent(of: .value, with: { snapshot in
if let snapshots = snapshot.children.allObjects as? [DataSnapshot] {
for snap in snapshots {
if snap.value == username {
completion(false)
}
}
completion(true)
} else {
completion(true) // TODO: check for errors before setting completion
}
})
}
// this function will set the username values in Firebase
func storeUsername() {
let usernameRef = ref.child("usernames")
usernameRef.updateChildValues(["\(userDataSource.sharedInstance.id!)" : username])
}
}
}
假设您已经处理了username
变量并设置了它的值,您将调用这样的函数:
checkUsernames({ (success) in
if success {
storeUsername()
// you may also want to update your "users" table here as well
} else { print("Duplicate Username") } // handle alert or something here
})
答案 1 :(得分:1)
您仍然需要使用with open('filename.txt', 'r') as f:
lines = f.readlines()
years = [line.split()[0] for line in lines if line.strip()!='']
nums = [line.split()[-1] for line in lines if line.strip()!='']
for year in sorted(set(years)):
values = [float(n) for y, n in zip(years, nums) if y==year]
avg = sum(values)/len(values)
print('Year: {}\tAverage: {:.2f}'.format(year, avg))
指明您要订购/过滤的属性:
queryOrdered(byChild:)