如何遍历Firebase datasnapshot子项？扑 [英] How to loop through a Firebase datasnapshot sub childrens? Flutter

问题描述

我有一个DataSnapshot JSON对象：

I have a DataSnapshot JSON object :

{fridge2: true, fridge1: true} //data pulled from a real time firebase database

我必须放入 fridge2 和 fridge1 在这样的列表中：

I have to put fridge2 and fridge1 in a list like this:

List<String> fridges;

我的尝试：

DataSnapshot fridgesDs = snapshot.value['fridges'];

    for (var fridge in fridgesDs) {
      if (fridge.value) {
        fridges.add(fridge.key);
      }
    }

给我这个错误：

type '_InternalLinkedHashMap<dynamic, dynamic>' is not a subtype of type 'Iterable<dynamic>'

推荐答案

我解决了。我曾经使用 print（fridgesDs.runtimeType）; 来获取firebase返回的变量类型。它实际上是一个HashMap： _InternalLinkedHashMap< dynamic，dynamic>
将返回的值转换为 Map 。最后，我使用forEach遍历了地图。这是最终版本：

I solved it. I used to print(fridgesDs.runtimeType); to get the type of variable returned by firebase. it is actually a HashMap: _InternalLinkedHashMap<dynamic, dynamic> The casted the returned value into a Map. Finally, I used forEach to loop through the map. Here is the final version:

 Map<dynamic, dynamic> fridgesDs = snapshot.value['fridges'];
//    print(fridgesDs.runtimeType);
    fridgesDs.forEach((key, value) {
      if (value) {
        fridges.add(key);
      }
    });

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