如何在新的Firebase数据库引用（Recyclerview）中进行排序 [英] how to sort in the new Firebase database reference (Recyclerview)

问题描述

我正在从用户名结构中提取数据，我想按名称或用户名进行排序。新的firebase数据库引用是否可能？我一直在四处寻找，我找不到任何关于它的事情。

这是我的代码：

  databaseReference = FirebaseDatabase.getInstance ）.getReference（）子（ 用户）。 
 
 
 $ b @Override 
 protected void onStart（）{
 super.onStart（）; 
 
 FirebaseRecyclerAdapter< addFriends，addFriendsViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter< addFriends，addFriendsViewHolder>（
 addFriends.class，
 R.layout.addfriends_row，
 addFriendsViewHolder.class，
 databaseReference 
）{
 @Override 
 protected void populateViewHolder（addFriendsViewHolder viewHolder，addFriends model，int position）{
 viewHolder.setName（model.getName（））; 
 viewHolder.setUsername（model.getUsername（））; 
} 
}; 
 addfriendsRecyclerView.setAdapter（firebaseRecyclerAdapter）; 
 
 
 
 $ b这里是我的firebase结构：
 
 
  {
asdadafdsgsaasfsa：{
name：juanito，
username：cacadeperro22
 $ bdasdsadadaf：{
name：cucu，
username：dsadadas
}，
dsadasddsa： {
name：username，
username：pisad
}，
dsdsada：{
name：name ，
用户名：用户名
}，
qUYxycDlMwYZ6r2WSA1TAacbdPh1：{
email：[e-mail]，
name ：Elvis De Abreu，
username：elvis0288
}，
qadfdafa：{
name：Josue Caca，
 用户名：chupapenes
}，
x123：{
name：fsf，
username：dadfasfd
} ，
xxxxxx：{
name：123，
username：culo
} 
} 
  
谢谢！ 
 
解决方案
编辑：走开了，回来完成答案。看到有人打我:) 
在你的FirebaseRecyclerAdapter构造函数中传递一个QueryRef，而不是数据库引用。
 
 pre $  databaseReference = FirebaseDatabase.getInstance（）。getReference（）。child（Users）; 
 
 ... 
 
 @Override 
 protected void onStart（）{
 super.onStart（）; 
 
 Query query = databaseReference.orderByChild（name）; //或... orderByChild（username）; 
 FirebaseRecyclerAdapter< addFriends，addFriendsViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter< addFriends，addFriendsViewHolder>（
 addFriends.class，
 R.layout.addfriends_row，
 addFriendsViewHolder.class，
 query 
）{
 @Override 
 protected void populateViewHolder（addFriendsViewHolder viewHolder，addFriends model，int position）{
 viewHolder.setName（model.getName（））; 
 viewHolder.setUsername（model.getUsername（））; 
} 
}; 
 addfriendsRecyclerView.setAdapter（firebaseRecyclerAdapter）; 
} 
  




I am pulling data from a username structure and I would like to sort by name or username. Is this possible with the new firebase database reference. I have been looking around and I cannot find anything about it.

here is my code:

databaseReference = FirebaseDatabase.getInstance().getReference().child("Users");

}

@Override
protected void onStart() {
    super.onStart();

    FirebaseRecyclerAdapter<addFriends,addFriendsViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<addFriends, addFriendsViewHolder>(
            addFriends.class,
            R.layout.addfriends_row,
            addFriendsViewHolder.class,
            databaseReference
    ) {
        @Override
        protected void populateViewHolder(addFriendsViewHolder viewHolder, addFriends model, int position) {
            viewHolder.setName(model.getName());
            viewHolder.setUsername(model.getUsername());
        }
    };
    addfriendsRecyclerView.setAdapter(firebaseRecyclerAdapter);
}

here is my structure in firebase:

{
  "asdadafdsgsaasfsa" : {
    "name" : "juanito",
    "username" : "cacadeperro22"
  },
  "dasdsadadaf" : {
    "name" : "cucu",
    "username" : "dsadadas"
  },
  "dsadasddsa" : {
    "name" : "username",
    "username" : "pisad"
  },
  "dsdsada" : {
    "name" : "name",
    "username" : "username"
  },
  "qUYxycDlMwYZ6r2WSA1TAacbdPh1" : {
    "email" : "[e-mail]",
    "name" : "Elvis De Abreu",
    "username" : "elvis0288"
  },
  "qadfdafa" : {
    "name" : "Josue Caca",
    "username" : "chupapenes"
  },
  "x123" : {
    "name" : "fsf",
    "username" : "dadfasfd"
  },
  "xxxxxx" : {
    "name" : "123",
    "username" : "culo"
  }
}

Thanks!

解决方案

EDIT: Had stepped away and came back to finish answer. Saw someone beat me to it :) Pass in a QueryRef in your FirebaseRecyclerAdapter constructor instead of the database reference.

databaseReference = FirebaseDatabase.getInstance().getReference().child("Users");

// ...

@Override
protected void onStart() {
    super.onStart();

Query query = databaseReference.orderByChild("name"); // or ...orderByChild("username");
FirebaseRecyclerAdapter<addFriends,addFriendsViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<addFriends, addFriendsViewHolder>(
        addFriends.class,
        R.layout.addfriends_row,
        addFriendsViewHolder.class,
        query
) {
    @Override
    protected void populateViewHolder(addFriendsViewHolder viewHolder, addFriends model, int position) {
        viewHolder.setName(model.getName());
        viewHolder.setUsername(model.getUsername());
    }
};
addfriendsRecyclerView.setAdapter(firebaseRecyclerAdapter);
}

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