为什么我会遇到这个错误 RangeError (index): Invalid value: Valid value range is empty？

Question

IM getting an error when using streambuilde and I cannot really figure out why. heres the error

RangeError (index): Invalid value: Valid value range is empty: 0
The relevant error-causing widget was
StreamBuilder<QuerySnapshot>
lib/chatmessenger/recent_conversations_page.dart:49

And heres my code

 @override
  Widget build(BuildContext context) {
    var firestore = FirebaseFirestore.instance;
    return Container(
      height: 50,
      width: widget._width,
      child: StreamBuilder<List<ConversationSnippet>>(
        stream: DatbaseService.instance.getUserConversations(user.uid),
        builder: (_context, _snapshot) {
          var _data = _snapshot.data;
          if (_data != null) {
            _data.removeWhere((_c) {
              return _c.timestamp == null;
            });
            if (_snapshot.data.isNotEmpty) {
              return ListView.builder(
                itemCount: _data.length,
                itemBuilder: (_context, _index) {
                  return StreamBuilder(.  here is the error thrownnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
                      stream: firestore
                          .collection('meinprofilsettings')
                          .where('uid', isEqualTo: _data[_index].uid)
                          .snapshots(),
                        
                      builder: (context, snapshot) {
                         DocumentSnapshot video =
                                      snapshot.data.docs[_index];
                         
                        return ListTile(
                          onTap: () {
                         
                          },
                          title: Text(video.data()['username']),

I marked in the code where the error is thrown and also you can see that I use the Documetnsnaoshot video in for the text in title. When im removing the Documetnsnapshot video the error is away. If you need more information please leave ac comment. What I do is getting the data of streambuilder and then create inside this a new streambuikder where I fetch data from firebase with the uid. And last but not least I wanna display these data.

So heres my firebase

And the doc id is the field _data[_index].uid. So this works.but what I need instead of the field 'uid' is the doc id of the collection "meinprfosilsettings " Heres the picture

Answer 1

IM getting an error when using streambuilde and I cannot really figure out why. heres the error

RangeError (index): Invalid value: Valid value range is empty: 0
The relevant error-causing widget was
StreamBuilder<QuerySnapshot>
lib/chatmessenger/recent_conversations_page.dart:49

And heres my code

 @override
  Widget build(BuildContext context) {
    var firestore = FirebaseFirestore.instance;
    return Container(
      height: 50,
      width: widget._width,
      child: StreamBuilder<List<ConversationSnippet>>(
        stream: DatbaseService.instance.getUserConversations(user.uid),
        builder: (_context, _snapshot) {
          var _data = _snapshot.data;
          if (_data != null) {
            _data.removeWhere((_c) {
              return _c.timestamp == null;
            });
            if (_snapshot.data.isNotEmpty) {
              return ListView.builder(
                itemCount: _data.length,
                itemBuilder: (_context, _index) {
                  return StreamBuilder(.  here is the error thrownnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
                      stream: firestore
                          .collection('meinprofilsettings')
                          .where('uid', isEqualTo: _data[_index].uid)
                          .snapshots(),
                        
                      builder: (context, snapshot) {
                         DocumentSnapshot video =
                                      snapshot.data.docs[_index];
                         
                        return ListTile(
                          onTap: () {
                         
                          },
                          title: Text(video.data()['username']),

I marked in the code where the error is thrown and also you can see that I use the Documetnsnaoshot video in for the text in title. When im removing the Documetnsnapshot video the error is away. If you need more information please leave ac comment. What I do is getting the data of streambuilder and then create inside this a new streambuikder where I fetch data from firebase with the uid. And last but not least I wanna display these data.

So heres my firebase

And the doc id is the field _data[_index].uid. So this works.but what I need instead of the field 'uid' is the doc id of the collection "meinprfosilsettings " Heres the picture