Flutter：Firebase身份验证和Firestore快照流 [英] Flutter: Firebase auth and Firestore snapshot stream

问题描述

在Flutter应用中，我正在使用Firebase进行身份验证和Firestore数据库。我也在尝试遵循BLOC模式。

In my flutter app I'm using firebase for the authentication and firestore database. I am also trying to follow the BLOC pattern.

成功登录后，我需要使用存储在文档中的一些数据来构建UI屏幕：

After succesfully login I need to build my UI screen using some data stored in a document:

 @override
  Widget build(BuildContext context) {

    return FutureBuilder(
      future: Auth.of(context).firebase.uid(), 
      builder: (context, snap){

        if(snap.hasData) {
          print("Your uid is ${snap.data}");
          return StreamBuilder(

            stream: Firestore.instance.collection('USERS').document(snap.data).collection('PHOTOS').document(
                widget.photoID).snapshots(),
            builder: (context, AsyncSnapshot<DocumentSnapshot> snap) {...}

现在，一切正常。

Auth是Firebase Auth的包装类，扩展了Inherited Widget的.uid（）方法。返回带有用户标识符的Future
然后我使用StreamBuilder来构建U我通过uid来获取DocumentSnapshot。

Auth is a wrapper class for Firebase Auth extending InheritedWidget where .uid() method returns a Future with the user identifier. Then I use a StreamBuilder to build the UI passing the uid to get a DocumentSnapshot.

所以这是我的问题：是否有更好的方法来实现这一目标，并避免将StreamBuilder嵌套在FutureBuilder中？

So here is my question: is there a better approach to achieve this and avoid nesting StreamBuilder inside FutureBuilder?

推荐答案

RxDart 是您所需要的，可以将 Future 和 Stream 组合在一起，然后再将它们传递给 StreamBuilder 。

RxDart is what you need, you can combine the Future and Stream before you pass them into a StreamBuilder.

  var mergedStream = Auth.of(context).firebase.uid().asStream().flatMap((uid) =>
      Firestore.instance
          .collection('USERS')
          .document(uid)
          .collection('PHOTOS')
          .document(widget.photoID)
          .snapshots());

然后您可以在 StreamBuilder

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