Flutter Firestore具有相同文档的两个StreamBuilder计为2次读取？

Question

In my Flutter app, will it count as two reads from Firestore if I have two nested StreamBuilders reading from the same document? Or is it cached in a way that it will only count as one read?

Here's an example of what I'm talking about.

StreamBuilder(
  stream: Firestore.instance.document(path).snapshots(),
  builder: (context, asnap){
    //Some nested widgets...
    return StreamBuilder(
      stream: Firestore.instance.document(path).snapshots(),
      builder: (context, asnap){
        return MyWidget();
      },
    );
  },
);

Answer 1

As far as I know, the Firestore client deduplicates these listeners. So if a first listener is already active for the exact same data, it won't attach a second listener. So you won't be charged for two reads, but (possibly even more important to your users) the data will only be transferred once.