Firebase使用endAt时间戳字段 [英] Firebase use endAt if timestamp field

问题描述

 年龄：25 
时间戳：1484089199472 
 
 code> 

插入的记录：



  @Exclude 
 public Map< String，Object> toMap（）{
 HashMap< String，Object> result = new HashMap<>（）; 
 
 result.put（age，age）; 
 result.put（timestamp，ServerValue.TIMESTAMP）; 
返回结果; 
 
 
 
 
 
 
如果我使用 endAt（24，age ）比它的工作好，这个项目是不可见的。
 
 
 
但是，如果我想在时间戳endAt使用它不工作。例如：
  endAt（100000，timestamp），该行保持可见状态。 
为什么？  
 
 
这是检查类型吗？ 
 
 
 
如何过滤？ 
 
 
我没有任何意见！ :( 
我希望有人可以帮助我！
谢谢！
 
 
 
 编辑： b 
 
查询获取实际的日行 
 
 
  @Override 
 public Query getQuery DatabaseReference databaseReference）{
 Date endTime = new Date（）; 
 endTime.setHours（23）; 
 endTime.setMinutes（59）; 
 endTime.setSeconds（59）; 
 
 return databaseReference 
 .child（toplist）
 .endAt（endTime.getTime（），timestamp）
 .orderByChild（point）
 .limitToFirst（50）; 
 
} 
  
数据
  @IgnoreExtraProperties 
 public class Rank {
 
 public int number; 
 public String username ; 
 public int point; 
 
 
 // [START post_to_map] 
 @Exclude 
 public Map< String，Object> toMap（）{
 HashMap< Stri ng，Object> result = new HashMap<>（）; 
 result.put（number，number）; 
 result.put（username，username）; 
 result.put（point，point）; 
 result.put（timestamp，ServerValue.TIMESTAMP）; 
返回结果; 
 
 
 $ b $ / code $ / pre 
 
 
添加新的随机项
  private void writeNewRandomTopListItem（）{
 Random rnd = new Random（）; 
 Rank item = new Rank（）; 
 item.username =Test+ rnd.nextInt（20000）; 
 item.point = rnd.nextInt（2000000）; 
 
 mDatabase.child（toplist）。push（）。setValue（item.toMap（））; 
 
 
 
 $ b $适配器
 
 $ pre> 查询postsQuery = getQuery（mDatabase）; 
 mAdapter = new FirebaseRecyclerAdapter< Rank，PostViewHolder>（Rank.class，R.layout.item_post，PostViewHolder.class，postsQuery）{
 @Override 
 protected void populateViewHolder（final PostViewHolder viewHolder，final Rank模型，final int位置）{
 
 viewHolder.bindToPost（model，position）; 
} 
}; 
 mRecycler.setAdapter（mAdapter）; 
  
 ... 
  toplist 
 -Ka8m3hN-vRjPZhKH3Rt 
 number：0 
 point：1269424 
 timestamp：148407253222471 
 username：Test 19727
 -Ka8m3hWRIQKL7faNqUS 
 number：0 
 point：1398061 
 timestamp：1484075322472 
 username：Test 17679
 
 
 
解决方案
您应该通过时间戳项目由客户端的 points 。这是描述这里。
 
 
 
我建议您使用这个查询来代替： 
 
 
  @Override 
 public Query getQuery（final DatabaseReference databaseReference）{
 Date endTime = new Date（）; 
 endTime.setHours（23）; 
 endTime.setMinutes（59）; 
 endTime.setSeconds（59）; 
 
 return databaseReference.child（toplist）。orderByChild（timestamp）
 .endAt（endTime.getTime（））。limitToFirst（50）; 
 
 
 
 
 
 $ b这样，您就可以告诉Firebase通过他们的某个子节点对您的节点进行排序在这种情况下，它将是 timestamp 。希望这有助于。
 
 
 
接下来，您需要在客户端对数据进行排序。一个问题是，从firebase的实时更改不会在 RecyclerView 内重新排序您的项目。例如。
 
 
我再次建议阅读这个回答。
 
I have records with this fields:
age: 25
timestamp: 1484089199472
This records inserted by:
@Exclude
public Map<String, Object> toMap() {
    HashMap<String, Object> result = new HashMap<>();

    result.put("age", age);
    result.put("timestamp", ServerValue.TIMESTAMP);
    return result;
}
If i use endAt(24,"age") than its work good, the item is invisible.

But if i want to use endAt in timestamp its not work. For example:
endAt(100000,"timestamp") and the row is stay visible.
Why? 

This is check the type? 

How can i filter it?

I dont have any idea! :( 
I hope someone can help me!
Thanks!

EDIT:

Query for get the actually day rows
 @Override
    public Query getQuery(final DatabaseReference databaseReference) {
        Date endTime = new Date();
        endTime.setHours(23);
        endTime.setMinutes(59);
        endTime.setSeconds(59);

        return databaseReference
                .child("toplist")
                .endAt(endTime.getTime(),"timestamp")
                .orderByChild("point")
                .limitToFirst(50);

    }
Data
@IgnoreExtraProperties
public class Rank{

    public int number;
    public String username;
    public int point;


    // [START post_to_map]
    @Exclude
    public Map<String, Object> toMap() {
        HashMap<String, Object> result = new HashMap<>();
        result.put("number", number);
        result.put("username", username);
        result.put("point", point);
        result.put("timestamp", ServerValue.TIMESTAMP);
        return result;
    }

}
Add new random item
private void writeNewRandomTopListItem() {
        Random rnd = new Random();
        Rank item = new Rank();
        item.username = "Test " + rnd.nextInt(20000);
        item.point = rnd.nextInt(2000000);

        mDatabase.child("toplist").push().setValue(item.toMap());
    }
Adapter
Query postsQuery = getQuery(mDatabase);
        mAdapter = new FirebaseRecyclerAdapter<Rank, PostViewHolder>(Rank.class, R.layout.item_post, PostViewHolder.class, postsQuery) {
            @Override
            protected void populateViewHolder(final PostViewHolder viewHolder, final Rank model, final int position) {

                viewHolder.bindToPost(model,position);
            }
        };
        mRecycler.setAdapter(mAdapter);
...
 toplist
   -Ka8m3hN-vRjPZhKH3Rt
     number: 0
     point:  1269424
     timestamp: 148407253222471
     username:  "Test 19727"
   -Ka8m3hWRIQKL7faNqUS
     number:  0
     point:  1398061
     timestamp:  1484075322472
     username: "Test 17679"

解决方案
You should order your nodes by the timestamp child first and secondly order the received items by points on the client side. This was described here.

I would suggest you to use this query instead:
@Override
public Query getQuery(final DatabaseReference databaseReference) {
    Date endTime = new Date();
    endTime.setHours(23);
    endTime.setMinutes(59);
    endTime.setSeconds(59);

    return databaseReference.child("toplist").orderByChild("timestamp")
            .endAt(endTime.getTime()).limitToFirst(50);
}
This way you are telling Firebase to sort your nodes by one of their child nodes which in this case would be timestamp. Hope this helps.

Next you would need to sort your data on the client side. A problem of this would be that realtime changes from firebase would not reorder your items inside a RecyclerView for example.

Once again I recommend reading through this answer.

                        
这篇关于Firebase使用endAt时间戳字段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！