arrays - 使用flutter从firestore获取用户数组数据
问题描述
在我的 firestore db 中,我的目录users
包含用户数据为documents
. 该文档有两个字段,String 'displayName' 和 Array 'friends'。我正在努力检索朋友数组并将其放入流中颤动的列表中。任何帮助表示赞赏。
我目前的代码如下:
Stream<List<Memo>> get memos {
var userdocs = Firestore.instance.collection('users').document(userid).document('friends');
// Complete request and do list conversions
// Do more work using results
}
我承认这个问题之前已经被问过,但我对颤振很陌生,异步编程并不完全理解答案
解决方案
flutter SDK
返回一个对象,该Stream
对象将随着时间的推移发出值(实时数据库)。在您的示例中,您正在分配一个Stream
值并期望一个List
. 在异步编程中,您必须订阅一个事件,以便每当发出一个值时,我们就可以执行我们想要的操作。
var userdocs
Firestore.instance
.collection("users")
.document(userid)
.get()
.then((DocumentSnapshot ds) {
userdocs = ds.data
})
或者await
如果你在一个async
函数中使用
var userdocs = await Firestore.instance
.collection("users")
.document(userid)
.get()
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