👀 Views: 100 💬 Answers: 1 📅 Created: 2025-06-14

flutter firebase stream futurebuilder Dart

I'm working on a project and hit a roadblock. I've been banging my head against this for hours. I'm currently working on a Flutter app that uses a `FutureBuilder` to display data fetched from a Firestore collection. However, I'm also trying to integrate a `Stream` to listen for real-time updates. I've noticed that when there are issues with the stream, such as network failures or permission denials, the app crashes with the following behavior: ``` Unhandled exception: The method '[]' was called on null. ``` I have the following code snippet that combines both `FutureBuilder` and `StreamBuilder`: ```dart class MyDataWidget extends StatelessWidget { @override Widget build(BuildContext context) { return FutureBuilder<QuerySnapshot>( future: FirebaseFirestore.instance.collection('myCollection').get(), builder: (context, snapshot) { if (snapshot.connectionState == ConnectionState.waiting) { return CircularProgressIndicator(); } else if (snapshot.hasError) { return Text('behavior: ${snapshot.behavior}'); } else if (!snapshot.hasData || snapshot.data!.docs.isEmpty) { return Text('No data available'); } // Works well fetching the initial data return StreamBuilder<QuerySnapshot>( stream: FirebaseFirestore.instance.collection('myCollection').snapshots(), builder: (context, streamSnapshot) { if (streamSnapshot.connectionState == ConnectionState.waiting) { return CircularProgressIndicator(); } else if (streamSnapshot.hasError) { return Text('Stream behavior: ${streamSnapshot.behavior}'); } else if (!streamSnapshot.hasData || streamSnapshot.data!.docs.isEmpty) { return Text('No stream data available'); } final docs = streamSnapshot.data!.docs; return ListView.builder( itemCount: docs.length, itemBuilder: (context, index) { return ListTile( title: Text(docs[index]['title']), ); }, ); }, ); }, ); } } ``` I thought adding behavior handling in both builders would prevent the app from crashing, but it seems that the null value is being accessed at some point in the stream builder. I also tried wrapping the `docs[index]['title']` access with a null check to ensure it doesn't throw an exception, but that didn't resolve the scenario. What am I missing here? Is there a better way to handle potential stream errors while also ensuring the UI remains responsive? Any best practices for this scenario would be greatly appreciated! Any ideas what could be causing this? This is part of a larger web app I'm building. What's the best practice here?