Flutter Firestore如何收听对一个文档的更改 [英] Flutter Firestore How To Listen For Changes To ONE Document

问题描述

我只想在一个文档被更改或更新时得到通知。获取更新的每个示例始终使用集合。我试图仅使用一个文档就实现了这一点，但是它从未得到任何更新。这是我现在无法使用的内容：

I just want to get notified whenever ONE document is changed or updated. Every example of getting updates is always using collections. I tried to implement that with only using one document and it never gets any updates. Here is what I have right now that doesn't work:

@override
Widget build(BuildContext context) {
StreamBuilder<DocumentSnapshot>(
    stream: Firestore.instance
        .collection("users")
        .document(widget.uid)
        .snapshots(),
    builder:
        (BuildContext context, AsyncSnapshot<DocumentSnapshot> snapshot) {
      user = snapshot.data.data as User;
    });

我已经调试了100次，但从未进入 builder：部分。顺便说一下，这对于文档参考不是问题。我在这里做什么错了？

I've debugged this 100 times and it never gets to the "builder:" section. And this is not a problem with the document reference by the way. What am I doing wrong here?

推荐答案

下面是一个例子

Firestore.instance
        .collection('Users')
        .document(widget.uid)
        .snapshots()
        .listen((DocumentSnapshot documentSnapshot) {

      Map<String, dynamic> firestoreInfo = documentSnapshot.data;

      setState(() {

        money = firestoreInfo['earnings'];

      });

    })
        .onError((e) => print(e));

但您在这里做错的是：

(BuildContext context, AsyncSnapshot<DocumentSnapshot> snapshot) {
      user = snapshot.data.data as User;
    });

用

(BuildContext context, AsyncSnapshot<DocumentSnapshot> snapshot) {
      var firestoreData = snapshot.data;

      String info = firestoreData['info'];
    });

这篇关于Flutter Firestore如何收听对一个文档的更改的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！