问题描述
我有一个这样的数据库
users/UID1/(用户1的用户名")
users/UID1/"Username" (of user 1)
/UID2/"Username" (of user 2)
/UID3/"Username" (of user 3)
/UID4/"Username" (of user 4)
以此类推.
我想检查用户名是否存在，但我无法与所有现有的UID陷入循环.目前，我已经尝试过:
I would like to check if the username exist but I don't manage to go in a loop with all existing UID.For now I have tried :
let databaseRef = Database.database().reference()
databaseRef.child("users").child("uid").child("Username").observeSingleEvent(of: DataEventType.value, with: { (snapshot) in
switch snapshot.value {
case let value as Bool where value:
// value was a Bool and equal to true
print ("username found")
default:
// value was either null, false or could not be cast
print ("username not found")
}
})
}
我不知道要放置什么(而不是child("uid"))循环进入数据库中的每个uid并检查用户名是否存在
I don't know what to put instead of child("uid") to loop into every uid in my database and check if a username exists
感谢您的帮助！
推荐答案
最简单的方法是在注册用户时，使用其唯一的UID创建用户并将所有数据保存在其中，就像在执行BUT一样创建一个名为用户名"的节点，该节点仅保存所有使用键作为其用户名并将其值设置为1的用户名，如下所示:
The easiest way of achieving this is when registering a user, create the user with their unique UID and save all their data inside there like you're doing BUT also create a node called "usernames" that simply holds all the usernames that are signed up with the key as their username and the value as 1 like so:
Usernames {
- username: 1
}
当用户注册然后输入用户名时，您可以像这样检查用户名是否存在:
When a user signs up and then goes to enter a username, you can check if it exists like so:
let username = "username that user has typed in"
let reference = Database.database().reference()
reference.child("usernames").observeSingleEvent(of: .value, with: { (snapshot) in
if snapshot.hasChild(username) {
print("Already exists")
} else {
print("Doesn't exist")
}
}, withCancel: nil)
感谢@FrankvanPuffelen，这是一种更有效的方式-无需循环访问每个用户名.
Thanks to @FrankvanPuffelen, here's a much more efficient way of doing this - without looping through every single username.
let reference = Database.database().reference()
reference.child("usernames").child(username).observeSingleEvent(of: .value, with: { (snapshot) in
if snapshot.exists() {
print("Username already exists")
} else {
print("Username doesn't already exist")
}
}, withCancel: nil)
这篇关于检查用户名是否存在于Firebase中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！