RangeError（索引）：无效值：不在0..5范围内（包括6）：Flutter SliverChildBuilderDelegate

Question

I was using using firestore with flutter SliverChildBuilderDelegate. SliverChildBuilderDelegate building a infinite index. but my firestore has only 6 documents. resulting

an error of RangeError (index): Invalid value: Not in range 0..5, inclusive: 7

how can I solve this?

There is a childCount property in SliverChildBuilderDelegate but not working also tried the offset.

new SliverFixedExtentList(
       itemExtent: 80.0,

delegate: new SliverChildBuilderDelegate(

(context, index ,{childCount:5}) => StreamBuilder<QuerySnapshot>(

stream: Firestore.instance.collection('books').orderBy('open_date')
.snapshots(),

builder: (context, snapshot) {

                        print("\n\n\n\n "+snapshot.data.documents.length.toString());
                        print("\n\n\n\n\n\n");
                      if (!snapshot.hasData) return CircularProgressIndicator();
                      else if(index<snapshot.data.documents.length){
                      return Card(
                        child: ListTile(

                          leading: child1,
                          title: Text(snapshot.data.documents[index]['title']),
                          subtitle:
                              Text(snapshot.data.documents[index]['result']),
                        ),
                      );
                      }else{
                      return Text("data");}
                    },
                  ),
            ),
          ),

Sorry for pasting a wrong formatted code. I tried a lot but may be stack doesn't support flutter dart

Answer 1

Try removing the childCount from the SliverChildBuilderDelegate arguments. Instead, place childCount directly after your code block for builder. (here is an example to look at: https://github.com/flutter/flutter/blob/master/examples/flutter_gallery/lib/demo/pesto_demo.dart )

    new SliverFixedExtentList(
       itemExtent: 80.0,

    delegate: new SliverChildBuilderDelegate(

    (context, index) => StreamBuilder<QuerySnapshot>(

    stream: Firestore.instance.collection('books').orderBy('open_date')
    .snapshots(),

    builder: (context, snapshot) {

                        print("\n\n\n\n "+snapshot.data.documents.length.toString());
                        print("\n\n\n\n\n\n");
                      if (!snapshot.hasData) return CircularProgressIndicator();
                      else if(index<snapshot.data.documents.length){
                      return Card(
                        child: ListTile(

                          leading: child1,
                          title: Text(snapshot.data.documents[index]['title']),
                          subtitle:
                              Text(snapshot.data.documents[index]['result']),
                        ),
                      );
                      }else{
                      return Text("data");}
                    },
                     childCount:5,
                  ),
            ),
          ),