Firebase snapshot.key不能返回实际的密钥？ [英] Firebase snapshot.key not returning actual key?

问题描述

我有一个基于用户ID搜索用户的查询。

  usersRef.queryOrderedByChild（email）。queryEqualToValue（email）.observeEventType（.Value，withBlock：{snapshot in 
如果snapshot.exists（）{
 print（user exists）
 print（snapshot.key）
  

查询返回正确的用户，但是 print（snapshot.key）从字面上返回单词users，而不是实际的用户ID 打印（快照）返回以下用户：

  （用户）{
 DELyncz9ZmTtBIKfbNYXtbhUADD2 = {
 email =[e-mail]; 
first_name= test; 
last_name= test; 
} ; 
  

如何获得 DELyncz9ZmTtBIKfbNYXtbhUADD2 ？I可以通过使用 let email = child.value [email] 来获取电子邮件，但是我不能得到密钥，因为它不是一个已命名的属性。 b
$ b

谢谢!!

编辑：感谢Frank的回答，更新了代码。获取不明确使用键

  query.observeEventType（.Value，withBlock ：{快照
 print（snapshot.key）
 
如果snapshot.exists（）{
 print（user exists）
 
 for child在snapshot.children {
 print（child.key）
  

解决方案

在某个位置运行查询时，结果将是匹配子项的列表。即使只有一个匹配的项目，结果也会是一个孩子的列表。

您正在打印所有子项的密钥。由于没有单一的结果，SDK会打印出您查询的位置/集合的关键字： users 。

您可能要查找的是循环匹配的子项并打印其键：

  let query = usersRef.queryOrderedByChild （email）。queryEqualToValue（email）
 query.observeEventType（.Value，withBlock：{snapshot in 
 for snapshot.children {$ b $ print（child.key）
} 
}）
  

I have a query that searches for a user based on user ID.

usersRef.queryOrderedByChild("email").queryEqualToValue(email).observeEventType(.Value, withBlock: { snapshot in
    if snapshot.exists() {
        print("user exists")
        print(snapshot.key)

The query returns the correct user, but the line print(snapshot.key) literally returns the word "users", and not an actual user ID. print(snapshot) returns the following user:

Snap (users) {
   DELyncz9ZmTtBIKfbNYXtbhUADD2 =     {
       email = "[e-mail]";
       "first_name" = test;
       "last_name" = test;
   };

How can I get DELyncz9ZmTtBIKfbNYXtbhUADD2? I can get the email by using let email = child.value["email"] but I can't get the key because it's not a named attribute.

Thanks!!

EDIT: Updated code thanks to Frank's answer. Getting ambiguous use of key

query.observeEventType(.Value, withBlock: { snapshot in
            print(snapshot.key)

            if snapshot.exists() {
                print("user exists")

                for child in snapshot.children {
                    print(child.key)

解决方案

When you run a query at a location, the result will be a list of the matching children. Even if there is only a single matching item, the result will be a list of one child.

You're printing the key of all resulting children. Since there is no single result, the SDK prints the key of the location/collection that you queried: users.

What you're likely looking for is to loop over the matching children and print their keys:

let query = usersRef.queryOrderedByChild("email").queryEqualToValue(email)
query.observeEventType(.Value, withBlock: { snapshot in
    for child in snapshot.children {
        print(child.key)
    }
})

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