使用FirebaseRecyclerAdapter排序项目的位置 [英] Sorting items position using FirebaseRecyclerAdapter

问题描述

在我的应用程序中，用户可以使用一个特殊的标准，即 orderByChild ，

轻松地对内容进行排序。在瑞士

  .orderByChild（Tag_country）。equalTo（Physics_Switzerland）;如果他们在瑞士寻找任何文件，那么
  

  .orderByChild（Country）。equalTo（Switzerland）; 
  

用户可以根据发布日期，浏览次数或金额。
$ b $ pre $ .orderByChild（Views）//按最高视图排序列表
.orderByChild（Brains）//按大多数喜欢排序列表
.orderByChild（TimeStamp）//按最新帖子排序列表\\ b


但是，用户可能不会多次对内容进行排序，因为我们可能都知道

< blockquote>

您一次只能使用一个顺序方式。

所以，像
<$ c $这样的东西OrderByChild（Tag_country）.equal（Physics_Switzerland）。OrderByChild（Views）;

/ p>

我一直试图根据文档被查看的次数对已经指定的查询进行排序，也就是按照降序排列，瑞士从最高点开始到最低点

FirebaseRecycler如何调整

  final Query DBquery = FirebaseDatabase.getInstance（）。getReference（）。child（PDF）。child（Content）
 .orderByChild（tag_Country）。equalTo（Chemistry_Switzerland）; 
 
 FirebaseRecyclerAdapter< pdfGstrings，Pdf_BlogViewHolder> fbRecyclerAdapter; 
 fbRecyclerAdapter = new FirebaseRecyclerAdapter< pdfGstrings，Pdf_BlogViewHold呃>（
 pdfGstrings.class，
 R.layout.pdf_g_card，
 Pdf_BlogViewHolder.class，
 DBquery 
）{
 
 PdfRecycler。 setAdapter（fbRecyclerAdapter）; 
 fbRecyclerAdapter.notifyDataSetChanged（）; 
  

视图如何被填充

 @Override 
 protected void populateViewHolder（final Pdf_BlogViewHolder viewHolder，final pdfGstrings model，final int position）{
 final String post_key = getRef（position）.getKey（）; 
渲染（viewHolder，model，post_key）; 
} 
}; 
  

我可以通过
$ b $访问每个Pdf Views b viewHolder.ViewCounts

查询

我该如何操纵\订购商品的位置，客户端，并基于一个整数值？这里是 viewHolder.ViewCounts

的整数值例子：将单元格与单元格顶部的325个视图对齐以编程方式显示92个视图。

儿童结构

  Pdf 
内容
 -Kd5YcEuE1yKTSdpaZi7 
Brains：2，
Country：Switzerland，
Tag_country：Chemistry_Switzerland，
TimeStamp：12849127519，
Views：92，
 
 -Kd5YcoijSDujaxpaZsE 
Brains：12，
Country：Switzerland，
Tag_country：Chemistry_Switzerland ，
TimeStamp14349127519 
Views：352，
 
 -Kd5YHDIUscDujaxpaZ13 
Brains：1，
 Country：Malaysia，
Tag_country：Mathematics_Malaysia，
TimeStamp14341221519 
Views：218，
 -Kd5YHDIUJAdhxaxpas93 
Brains 91，
国家：阿根廷，
Tag_country：Archaeology_Argentine，
时间戳：14949127519，
Views：928，
  

解决方案

在我的查询中， p>

OrderByChild（Tag_country_views）

安静简单：

• 使用增量方法将整数保留在子结构中
  
• 创建另一个值，它将Views值包装成一个字符串 String.valueOf（vh.Tag +_+ vh.Country +_+ vh.ViewsCount）


• 不要单独使用 OrderByChild ，可以考虑使用 startAt 和 limitTo 以及
  

例如：用户是否会筛选联合王国最常见的数学文档？然后，所有需要做的是

$ p $ code OrderByChild（Tag_Country_Views）
.startAt（Mathematics_United Kingdoms
.limitToFirst（DocumentsCount）;

（结果）

另外还有一个小技巧需要，计数应该，最好开始在 1,000,000,000 的意见，而它的增量仍然在 1 +

除以10亿，并使用模数运算符将揭示实际的查看次数

int CarrotCake = views％1000000000;

In my application, users can easily sort the content with one special criterion, that is orderByChild.

if they hunt for physics document in Switzerland

    .orderByChild("Tag_country").equalTo("Physics_Switzerland");

if they hunt for any document in Switzerland

    .orderByChild("Country").equalTo("Switzerland");

Users can sort contents based on their publish date, the number of times they have been viewed or the amount of brains\likes a single post has.

.orderByChild("Views") //  sort list by highest views
.orderByChild("Brains") //  sort list by most likes\brains 
.orderByChild("TimeStamp") //  sort list by newest post\edit

However, a user may not sort the content more than once, as we may all know

You can only use one order-by method at a time. Calling an order-by method multiple times in the same query throws an error.

So something like OrderByChild("Tag_country).equal("Physics_Switzerland").OrderByChild("Views");

will actually crash your app

I've been attempting to sort an already specified query based on the number of times a document has been viewed. That is, in a descending order, show me physics documents in Switzerland starting from the highest to the lowest views

How the FirebaseRecycler is being adjusted

 final Query DBquery = FirebaseDatabase.getInstance().getReference().child("PDF").child("Content")
                .orderByChild("tag_Country").equalTo("Chemistry_Switzerland");

        FirebaseRecyclerAdapter<pdfGstrings, Pdf_BlogViewHolder> fbRecyclerAdapter;
        fbRecyclerAdapter = new FirebaseRecyclerAdapter<pdfGstrings,  Pdf_BlogViewHolder>(
                pdfGstrings.class,
                R.layout.pdf_g_card,
                Pdf_BlogViewHolder.class,
                DBquery
        ) {

        PdfRecycler.setAdapter(fbRecyclerAdapter);
        fbRecyclerAdapter.notifyDataSetChanged();

How the view is being populated

 @Override
            protected void populateViewHolder(final Pdf_BlogViewHolder viewHolder, final pdfGstrings model, final int position) {
                final String post_key = getRef(position).getKey();
                Render(viewHolder, model, post_key);
            }
        };

I am able to access each Pdf Views count by

viewHolder.ViewCounts

The query

How may I manipulate\reorder the items positions, client-side, and based on an integer value? Here the integer value of viewHolder.ViewCounts

Example : Align the cell with 325 views on top of the cell with 92 views, programmatically.

Children Structure

Pdf
   Content
      -Kd5YcEuE1yKTSdpaZi7    
          "Brains" : 2,
          "Country" : "Switzerland",
          "Tag_country" : "Chemistry_Switzerland",
          "TimeStamp" : 12849127519,
          "Views" : 92,

      -Kd5YcoijSDujaxpaZsE    
          "Brains" : 12,
          "Country" : "Switzerland",
          "Tag_country" : "Chemistry_Switzerland",
          "TimeStamp" 14349127519
          "Views" : 352,

     -Kd5YHDIUscDujaxpaZ13   
          "Brains" : 1, 
          "Country" : "Malaysia",
          "Tag_country" : "Mathematics_Malaysia",
          "TimeStamp" 14341221519
          "Views" : 218,
     -Kd5YHDIUJAdhxaxpas93    
          "Brains" 91,
          "Country" : "Argentine",
          "Tag_country" : "Archaeology_Argentine",
          "TimeStamp": 14949127519,
          "Views" : 928,

解决方案

In my Query I was struggling concating an integer inside a string

OrderByChild("Tag_country_views")

The solution was quiet simple :

• Keep the integer in your child structure with it's incrementing method
• Create another value, which wrap the Views value into a String String.valueOf(vh.Tag+"_"+vh.Country+"_"+vh.ViewsCount)
• Instead of OrderByChild alone, consider using startAt and limitTo as well

for instance: Would a user filter for the most seen mathematical document in the United Kingdoms? then, all that needs to be done is

 OrderByChild("Tag_Country_Views")
 .startAt("Mathematics_United Kingdoms)
 .limitToFirst(DocumentsCount);

(result)

Also there is one minor trick needed, the count ought to, preferably, begin at 1,000,000,000 views, while it's incrementation remains at 1+

This way, querying for String_value is feasible.

Dividing by one billion and using the modulus operator will reveal the actual view count

int CarrotCake = views % 1000000000;

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