计数在 Firestore Flutter 中值匹配的文档

Question

im getiing 20 comments value but i only enter only two comments on my post im not finiding this solution. in the above im using stream builder error is there where im putting query on my text.

stream builder:

 StreamBuilder(
   stream: FirebaseFirestore.instance.collection("post").snapshots(),
     builder: (BuildContext context,AsyncSnapshot<QuerySnapshot>snapshot){

       return ListView.builder(
               shrinkWrap: true,
               scrollDirection: Axis.vertical,
                itemCount: snapshot.data.docs.length,
                 physics: NeverScrollableScrollPhysics(),
                 itemBuilder: (_,index) {
               return 
     Text('${FirebaseFirestore.instance.collection("comments").where("postid",isEqualTo: 
     snapshot.data.docs[index].id).get().toString().length}')

    }

Answer 1

You must use the .length on the snapshot's docs property directly as shown below:

final QuerySnapshot snapshot = await Firestore.instance.collection('products').where("postid",isEqualTo: snapshot.data.docs[index].id).get();
final int documents = snapshot.docs.length;

Another way using Future:

FirebaseFirestore.instance
        .collection("products")
        .where("postid", isEqualTo: snapshot.data.docs[index].id)
        .get()
        .then((snapshot) => {
                print(snapshot.docs.length);
            });

Answer 2

so i know the solution of this so i post the example of above problem

StreamBuilder(stream:FirebaseFirestore.instance.collection("comment").where("postid",isEqualTo: snapshot.data.docs[index].id).snapshots(),
                                                        builder: (context,projsnap){
                                                        final int documents = projsnap.data.docs.length;
                                                        return Text('${documents}');
                                                    }),