我一直在关注使用实时数据库的官方 Firebase 教程:https://www.youtube.com/watch?v=sXBJZD0fBa4
我能够从 firebase 实时数据库中提取所有数据。但是,下面的方法提供了数据列表,但不引用父键 (snapshot.key)。理想的情况是在 Item 类 (item.key) 中拥有一个键属性,这样我就可以直接从列表中调用它。
class DatabaseModel {
final itemsRef = FirebaseDatabase.instance.ref().child('/Contents');
Stream<List<Items>> getItemssStream() {
final itemsStream = itemsRef.onValue;
final streamToPublish = itemsStream.map((event) {
final itemsMap = Map<String, dynamic>.from(event.snapshot.value as Map<String, dynamic>);
final itemsList = itemsMap.entries.map((element) {
return Items.fromRTDB(Map<String, dynamic>.from(element.value));
}).toList();
return itemsList;
});
return streamToPublish;
}
}
class Items{
final String item;
final String expiryDate;
final String quantity;
final String user;
Items({required this.item, required this.expiryDate, required this.quantity, required this.user});
//Mapping from real-time database
factory Items.fromRTDB(Map<String, dynamic> data) {
return Items(
item: data['item'],
expiryDate: data['exp'],
quantity: data['qty'],
user: data['user'],
);
}
}
在此代码中,您仅使用element.value
结果中每个节点的:
return Items.fromRTDB(Map<String, dynamic>.from(element.value));
如果您还想获取每个项目的密钥,则还必须使用element.key
在那里并将其传递给你的Items
object.
像这样的事情:
Items.fromRTDB(element.key, Map<String, dynamic>.from(element.value));
...
class Items{
final String key;
final String item;
final String expiryDate;
final String quantity;
final String user;
Items({required this.key, required this.item, required this.expiryDate, required this.quantity, required this.user});
//Mapping from real-time database
factory Items.fromRTDB(String key, Map<String, dynamic> data) {
return Items(
key: key,
item: data['item'],
expiryDate: data['exp'],
quantity: data['qty'],
user: data['user'],
);
}
}
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