如何管理Firebase数据库密钥？ [英] How to manage firebase database keys?

问题描述

当使用firebase（或任何基于id的数据集合数据）时，我几乎总是要跟踪给定值的关键字。例如，让我们假设我有位置类与纬度和经度字段。当我从firebase下载的时候，除了它的两个字段之外，我还想跟踪关键字（使用push（）生成的节点值，例如-K_esEYXNfMBNmgF3fO4），它被下载，所以我稍后可能会更新它，删除它等。只有两个解决方案：

1. 复制数据并将键值添加为另一个Location类字段。这不能很好地工作，因为我必须在执行push（）之后设置键值。

创建通用的包装类，保持键和对象：



  public class Key< T> {
 
 private final String key; 
私人最终T值; 
 
公钥（字符串键，T值）{
 this.value = value; 
 this.key = key; 
} 
 
 public String key（）{
 return key; 
} 
 
 public T value（）{
返回值; 
 
 
 code 
 
 
 
我正在使用第二种方法，但看起来不太好。我有这个Key类基本上遍及我所有的代码库，当使用RxJava时，大量的方法有这样的返回类型： Observable< Key< Location>>  。
解决方案
实际上，我觉得这很荒唐。 
 
 
或者，您可以在POJO中包含密钥并使用 @Exclude 进行注释，以将其排除在序列化之外。  
When using firebase (or any database that aggregates data basing on ids)  I nearly always have to keep track of a key of a given value. For example let's assume I have Location class with latitude and longitude fields. When I download if from firebase, besides its two fields, I also want to keep track of the key (node value generated with push() e.g. -K_esEYXNfMBNmgF3fO4) it was downloaded from so I may later update it, delete it etc. I see only two solutions:

Duplicate the data and add key value as another Location class field. That doesn't work nicely because I have to set the key  value only after I executed push().
Create generic wrapper class that will keep key and object:
public class Key<T> {

  private final String key;
  private final T value;

  public Key(String key, T value) {
      this.value = value;
      this.key = key;
  }

  public String key() {
      return key;
  }

  public T value() {
      return value;
  }
}

I am using the second approach but it doesn't look really nice. I have this Key class basically throughout all my codebase and when using RxJava  plenty of methods have a return type like this: Observable<Key<Location>> and that just looks ridiculous.
解决方案
What you call ridiculous actually looks quite normal to me. 

Alternatively you can include the key in the POJO and annotate it with @Exclude to exclude it from the serialization.

                        
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