我正在Flutter中创建一个杂货店应用程序，但我无法将更新后的购物车值显示到文本小部件。
这是我的列表视图

var fire_storedb = FirebaseFirestore.instance.collection("vegetables").snapshots();

Container(
    margin: const EdgeInsets.only(top: 2),
    alignment: Alignment.center,
    child: StreamBuilder(
        stream: fire_storedb,
        builder: ((context, snapshot) {
          if (!snapshot.hasData) return const CircularProgressIndicator();
          return (ListView.builder(
            shrinkWrap: true,
            scrollDirection: Axis.vertical,
            itemCount: snapshot.data!.docs.length,
            itemBuilder: (context, index) {
              return (grocery_list(snapshot, index, context,values45));
            },
          ));
        })),
  ),

下面是我的growth_list函数，它是从ListView调用的........

Row(mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                         children: [
        
                              InkWell(
                                  child: Icon(FontAwesomeIcons.minus),
                              onTap: () async {
                                String? grocery_id =
                                    snapshot.data?.docs[index].reference.id;
                                FirebaseFirestore.instance
                                    .collection("Cart")
                                    .where("grocery_id", isEqualTo: grocery_id)
                                    .get()
                                    .then((value) {
                                  value.docs.forEach((element) {
                                    FirebaseFirestore.instance
                                        .collection("Cart")
                                        .doc(element.id)
                                        .delete()
                                        .then((value) {
                                      print("Success!");
                                    });
                                  });
                                });
                              }),      //Inkwell for delete item from cart

                          VerticalDivider(width: 10,),    ////// Vertical Divider
                          

                          VerticalDivider(width: 10,),    ////// Vertical Divider
    
                          InkWell(
                            child: Icon(FontAwesomeIcons.plus),
                            onTap: () async {
                              SharedPreferences sharedPreferences =
                                  await SharedPreferences.getInstance();
                              var email =
                                  sharedPreferences.getString("email").toString();
                              String? docid =
                                  snapshot.data?.docs[index].reference.id;
    
                              Map<String, String?> data_to_save = {
                                "grocery_id": docid,
                                "quantity": "1",
                                "email": email,
                                "name": snapshot.data!.docs[index]['name'],
                                "price": snapshot.data!.docs[index]['price'],
                                "si": snapshot.data!.docs[index]['si'],
                                "image": snapshot.data!.docs[index]['image'],
                              };
                              var collectionRef = await FirebaseFirestore.instance
                                  .collection("Cart");
                              collectionRef.add(data_to_save);
                            },
                          ),        // Inkwell for add item to cart
                        ],
                      ),

我想把下面的代码之间的两个垂直分隔符作为一个文本宽显示没有项目添加到购物车。有人能帮忙吗。？我可以得到购物车的值在cart_value，但无法显示它的文本小部件。

FirebaseFirestore.instance.collection("Cart").get().then((value) {
          value.docs.forEach((element) {
            FirebaseFirestore.instance.collection("Cart").doc(element.id).get().then((value2) => {
              if(value2.data()!['grocery_id']==docid)
                cart_value = (value2.data()['quantity'])
            });
          });
        });