从Firebase实时获取表到回收站视图之间的数据 [英] Get data from firebase realtime between table to recycler view
问题描述
我从Firebase读取数据时遇到问题.但是,我只能获取单个数据,但是,我需要获取该数据的列表.由于这是我使用Firebase的第一项工作.我过去只用过SQL.
I am having problem reading data from Firebase. But, I just can get single data but, I need to get list of that data. Since it is my first work using Firebase. I have only used SQL in the past.
这是我的Firebase结构.
Here is My Firebase Structure.
"UserEO" : {
"RZ5piQEWcoSonDYPu3NSKBrXTbW2" : {
"-LdK1ZgjaKvXFjUeq-Yj" : {
"keyUID" : "RZ5piQEWcoSonDYPu3NSKBrXTbW2"
},
"-LdK264lPX9eBBzYe0m4" : {
"keyUID" : "RZ5piQEWcoSonDYPu3NSKBrXTbW2"
}
}
},
"eventOrganizer" : {
"-LdK1ZgjaKvXFjUeq-Yj" : {
"deskripsi" : "USMA is .. ",
"namaGrup" : "UKM USMA",
"website" : "ukm.usma.blogspot.com"
},
"-LdK264lPX9eBBzYe0m4" : {
"deskripsi" : "LPM KOMPEN is ..",
"namaGrup" : "UKM LPM KOMPEN",
"website" : ""
} },
"users" : {
"RZ5piQEWcoSonDYPu3NSKBrXTbW2" : {
"email" : "kiranana@gmail.com",
"nama" : "kirana"
}
}
这是我的代码,我想选择该用户加入的组eventOrganizer.
Here is my code, I want to select group eventOrganizer that user joining.
userId=auth.getCurrentUser().getUid();
recyclerView = (RecyclerView) findViewById(R.id.rv_grupeo);
layoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);
recyclerView.setLayoutManager(layoutManager);
grupEOModelList = new ArrayList<>();
adapter = new GrupEOAdapter(grupEOModelList,GrupEO.this);
recyclerView.setAdapter(adapter);
DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference("UserEO").child(userId);
databaseReference.addValueEventListener(valueEventListenerAdmin);
}
ValueEventListener valueEventListenerAdmin = new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
String getKey = null;
if (dataSnapshot.exists()){
for (DataSnapshot snapshot : dataSnapshot.getChildren()){
getKey = snapshot.getKey();
}
final DatabaseReference databaseReferenceEO = FirebaseDatabase.getInstance().getReference("eventOrganizer");
databaseReferenceEO.orderByKey().equalTo(getKey).addValueEventListener(valueEventListener);
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
};
ValueEventListener valueEventListener = new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
grupEOModelList.clear();
if (dataSnapshot.exists()){
for (DataSnapshot snapshot : dataSnapshot.getChildren()){
GrupEOModel grupEOModel = snapshot.getValue(GrupEOModel.class);
grupEOModelList.add(grupEOModel);
}
adapter.notifyDataSetChanged();
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
};}
提前
谢谢.
推荐答案
我想问题出在这里:
final DatabaseReference databaseReferenceEO = FirebaseDatabase.getInstance().getReference("eventOrganizer");
databaseReferenceEO.orderByKey().equalTo(getKey).addValueEventListener(valueEventListener);
我不知道将valueListener嵌入OnDataChange内是一个好主意,我建议您删除它并使用回调.只需使用以下命令将UserEO转换为列表即可:
I don't know it it's a good ideia to embedd a valueListener inside OnDataChange, I would suggest you remove this and work with callbacks. Just convert UserEO in a list using this:
ArrayList<UserEO> td = (ArrayList<UserEO>) dataSnapshot.getValue();
通过回调将其返回,然后您可以使用valueEventListener为每个键调用一个方法.
return it in a callback, then you can call for each key an method with your valueEventListener.
我也想建议您简化一下.您可以在用户内部添加另一个子对象,例如 events:{"LdK1ZgjaKvXFjUeq",-LdK264lPX9eBBzYe0m4"}
,这样每个用户都会有一个事件键列表,很简单.
充分利用NoSQL的关键是精心设计数据,针对查询优化数据,我可以看到您仍然像SQL表那样思考,但是没关系,因为您仍在学习中.
I also would like to suggest you a simplification. You can add another child inside users like, events: {"LdK1ZgjaKvXFjUeq", "-LdK264lPX9eBBzYe0m4"}
, so each user will have a list of events key, pretty straightfoward.
The key of a good use of NoSQL is to design well your data, optimizing it for queries, I can see you're still thinking like SQL tables, but it's ok since you're still learning.
这篇关于从Firebase实时获取表到回收站视图之间的数据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IT屋!