Firebase REST API使用浅数据 [英] Firebase REST API working with shallow data

问题描述

我正在查看 Firebase REST API 的文档，并指出
$ b

浅 - 这是一项高级功能，旨在帮助您处理大型数据集，而无需下载所有内容。将其设置为true以限制在某个位置返回的数据的深度。如果该位置的数据是JSON基元（字符串，数字或布尔值），则其值将简单地返回。如果该位置的数据快照是JSON对象，则每个键的值将被截断为true。

但是，发现似乎总是将值设置为true，无论它是否是一个JSON基元或对象？

例如从我读过的东西我期望下面的调用

https://samplechat.firebaseio-demo.com/message_list/-K6ojd3dJQ3AVi36cruT/.json?print=pretty&shallow=true 返回

  {
text：Ahoy！，
user_id ：jack
} 
  

取而代之的是

  {
text：true，
user_id：true 
} 
  
 
 $ b我明白在这个例子中我提供的浅度并不是必须的，因为它是最低级别的，但是我发现这个问题也是我自己的数据在更高的水平是一切正在返回true。
 
 
 
有没有办法重新使用浅参数来建立JSON基元的值？ 
 
解决方案
当您使用<$ c查询Firebase REST API $ c> shallow = true ，无论数据的类型如何，它都会返回 true 在它下面。没有办法改变这种行为。
 
 
 
有关原始值的文档适用于更深入地查询一个层次。你的情况，如果你运行这个查询： https://samplechat.firebaseio-demo.com/message_list/-K6ojd3dJQ3AVi36cruT/text.json?print=pretty&shallow=true ，你会得到嗨！ 
 
 
 
 $ <$> $ $ $ > https://samplechat.firebaseio-demo.com/message_list/-K6ojd3dJQ3AVi36cruT/.json?print=pretty  
  {
text：Ahoy！，
user_id：jack
} 
  
  
 
 
  https://samplechat.firebaseio-demo.com/message_list/-K6ojd3dJQ3AVi36cruT/.json?print=pretty&shallow=true  
  {
text：true，
user_id： true 
 
 code $ pre $ b $ li $ p $ lt; p $ lt; code> https：// samplechat。 / b 
 $ b 
  喂！ 
  
 
 
  
I am looking at the documentation for the Firebase REST API and it states that 

  
Shallow - This is an advanced feature, designed to help you work with large datasets without needing to download everything. Set this to true to limit the depth of the data returned at a location. If the data at the location is a JSON primitive (string, number or boolean), its value will simply be returned. If the data snapshot at the location is a JSON object, the values for each key will be truncated to true.
However from what I have found it seems to always set the value to true regardless of whether it is a JSON primitive or object?

eg from what I have read I would expect the below call

https://samplechat.firebaseio-demo.com/message_list/-K6ojd3dJQ3AVi36cruT/.json?print=pretty&shallow=true to return
{
    "text" : "Ahoy!",
    "user_id" : "jack"
}
instead it is returning 
{
    "text" : true,
    "user_id" : true
}
I understand in this example I provided shallow isn't required as it is the lowest level, however I have found this issue also with my own data at higher levels were everything is returning true.

Is there a way to return the value of a JSON primitive as suggested using the shallow param?
解决方案
When you query the Firebase REST API with shallow=true, it will return true for any key that exists on the level that you query, regardless of the type of the data underneath it. There is no way to change that behavior.

The documentation about primitive values applies when you query one level deeper. In your case, if you run this query: https://samplechat.firebaseio-demo.com/message_list/-K6ojd3dJQ3AVi36cruT/text.json?print=pretty&shallow=true, you get back "Ahoy!"

So:


https://samplechat.firebaseio-demo.com/message_list/-K6ojd3dJQ3AVi36cruT/.json?print=pretty
{
  "text" : "Ahoy!",
  "user_id" : "jack"
}

https://samplechat.firebaseio-demo.com/message_list/-K6ojd3dJQ3AVi36cruT/.json?print=pretty&shallow=true
{
  "text" : true,
  "user_id" : true
}

https://samplechat.firebaseio-demo.com/message_list/-K6ojd3dJQ3AVi36cruT/text.json?print=pretty&shallow=true
"Ahoy!"



                        
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