Gson从对象中制作出类似firebase的json [英] Gson make firebase-like json from objects

问题描述

过去手动创建的数据列表，这些数据本地存储在数据库中。现在我想分析这些数据并将它们通过 import json 选项放入firebase dbs中，但是我得到的内容看起来不像firebase生成的json。

我得到的是：

  [
 {
id：id_1 ，
text：一些文本
}，
 {
id：id_2，
text：some text2
 $，
 ... 
] 
  

我想要的是像这样：

  {
id_1：{
text：some text， 
id：id_1
}，
id_2：{
text：some text2，
id：id_1 
}，
 ... 
} 
  

我的卡片类

  class卡{
私人字符串ID; 
私人字符串文本; 
 
 
 $ / code> 

检索资料



  //返回卡片列表
 List< Card> cards = myDatabase.retrieveData（）; 
 Gson gson = new Gson（）; 
 String data = gson.toJson（cards）; 
  

所以我该如何实现这个（看起来对我而言）动态命名的json属性，看起来像那些由firebase产生的？



编辑：
我发现gson有可以改变字段名称的FieldNamingStrategy接口。但它看起来并不像我想要的那样动态。

EDIT2
我的临时修复只是覆盖toString（）

  @Override 
 public String toString（）{
 return\+ id +\：{+ 
\ text \：+\+ text +\，+ 
\id \：+\+ id +\， + 
\type \：+\+ type +\+ 
'}'; 
 
  

解决方案

将每个对象存储为字符串而不是对象。

您需要序列化一个对象才能获取该数据，而不是列表。例如，使用Map

  List< Card> cards = myDatabase.retrieveData（）; 
地图< Map< String，Object>> fireMap = new TreeMap<>（）; 
 int i = 1; （卡c：卡）
 {
 Map< String，Object> cardMap = new TreeMap<>（）; 
 cardMap.put（text，c.getText（））; 
 fireMap.put（id_+（i ++），cardMap）; 
} 
 Gson gson = new Gson（）; 
字符串数据= gson.toJson（fireMap）; 
  

In the past a manually created as list of data, which was stored locally in a database. Now I would like to parse those data and put them through import json option into firebase dbs, but what I get doesn't look like firebase generated json.

What I get is:

[  
   {  
      "id":"id_1",
      "text":"some text"
    },
    {  
      "id":"id_2",
      "text":"some text2"
    },
    ...
]

what I want is something like this:

{  
   "id_1": {  
      "text":"some text",
      "id":"id_1"
    },
    "id_2":{  
      "text":"some text2",
      "id":"id_1"
    },
    ...
}

my Card class

class Card{
    private String id;
    private String text;

}

retrieving data

//return list of card
List<Card> cards =myDatabase.retrieveData();
Gson gson = new Gson();
String data = gson.toJson(cards);

So how I can I achieve this (it looks to me) dynamically named properties for json that look like those generated by firebase ?

EDIT: I found that gson has FieldNamingStrategy interface that can change names of fields. But it looks to me it's not dynamic as I want.

EDIT2 my temp fix was to just override toString()

 @Override
 public String toString() {
     return "\""+id+"\": {" +
                     "\"text\":" + "\""+text+"\","+
                     "\"id\":" +"\""+ id +"\","+
                     "\"type\":"+ "\""+ type +"\""+
             '}';
    }

解决方案

Your "temp fix" will store each object as a string not a object.

You need to serialize an object to get that data, not a list.

For example, using a Map

List<Card> cards = myDatabase.retrieveData();
Map<Map<String, Object>> fireMap = new TreeMap<>();
int i = 1;
for (Card c : cards) {
    Map<String, Object> cardMap = new TreeMap<>();
    cardMap.put("text", c.getText());
    fireMap.put("id_" + (i++), cardMap);
}
Gson gson = new Gson();
String data = gson.toJson(fireMap);

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