如何检索在firebase的所有键 [英] how to retrieve all the keys in firebase android
本文介绍了如何检索在firebase的所有键的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
这是一个很好的选择,是我的数据结构
我想检索矩形框中的单个键下的两个键。我有在矩形框中的钥匙。所以如何将这两个键?
解决方案
所有你需要做的是做一个嵌套的查询。首先找到父母的密钥,然后将该密钥传递给下一个查询,然后找到它的子元素。
列表< user> userList = new ArrayList();
pre>
mdatabaseRef.addValueEventListener(新ValueEventListener(){
@覆盖
公共无效onDataChange(DataSnapshot dataSnapshot){
为(DataSnapshot孩子:dataSnapshot.getChildren()) {
String key = child.getKey();
fun(key);
}
private void fun(String key){
mdatabaseRef.child(键).addValueEventListener(新ValueEventListener(){
@覆盖
公共无效onDataChange(DataSnapshot dataSnapshot){为(DataSnapshot孩子:dataSnapshot.getChildren()){
User user = postsnapshot.getValue(User.class);
userList.add(user);
}
}
I want to retrieve all the keys under single key, tried many things, but nothing work till now.
This is my data structure
I want to retrieve two keys which are under single key in rectangle box. I have key which is in rectangle box. so how to these two keys ?
解决方案All You have to do is do a nested query .! first find key of parent then get pass that key to next query and then find its children.!
List<user> userList=new ArrayList(); mdatabaseRef.addValueEventListener(new ValueEventListener() { @Override public void onDataChange(DataSnapshot dataSnapshot) { for (DataSnapshot child: dataSnapshot.getChildren()){ String key = child.getKey(); fun(key); } private void fun(String key){ mdatabaseRef.child(key).addValueEventListener(new ValueEventListener() { @Override public void onDataChange(DataSnapshot dataSnapshot) {for (DataSnapshot child: dataSnapshot.getChildren()){ User user= postsnapshot.getValue(User.class); userList.add(user); } }
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