check null safety

lib/pages/carton/model/carton_model.dart

@@ -12,7 +12,7 @@ import 'package:logging/logging.dart';
 
 class CartonModel extends BaseModel {
   List<Carton> _boxes = [];
-  PaginatorListener? cartonsByFilter;
+  late PaginatorListener<Carton> cartonsByFilter;
 
   final log = Logger('CartonModel');
   List<Carton> get boxes => _selectedIndex == 1
@@ -24,8 +24,8 @@ class CartonModel extends BaseModel {
   int _selectedIndexFilter = 1;
   bool isLoading = false;
 
-  StreamSubscription<QuerySnapshot> listener;
-  StreamSubscription<QuerySnapshot> cartonListener;
+  StreamSubscription<QuerySnapshot>? listener;
+  StreamSubscription<QuerySnapshot>? cartonListener;
   static List<ShipmentStatus> statusHistory = [
     ShipmentStatus(status: "Packed", date: DateTime(2020, 6, 1), done: true),
     ShipmentStatus(status: "Shipped", date: DateTime(2020, 6, 5), done: false),
@@ -101,7 +101,7 @@ class CartonModel extends BaseModel {
 
   @override
   void privilegeChanged() {
-    if (user != null || !user.hasCarton()) {
+    if (user != null || !user!.hasCarton()) {
       _initData();
     }
   }
@@ -119,12 +119,12 @@ class CartonModel extends BaseModel {
   }
 
   Future<void> _loadBoxes() async {
-    if (user == null || !user.hasCarton()) return;
+    if (user == null || !user!.hasCarton()) return;
     String path = "/$cartons_collection/";
-    if (listener != null) listener.cancel();
+    if (listener != null) listener!.cancel();
     _boxes = [];
     try {
-      listener = Firestore.instance
+      listener = FirebaseFirestore.instance
           .collection("$path")
           .where("status",
               whereIn: [carton_packed_status, carton_shipped_status])
@@ -133,9 +133,10 @@ class CartonModel extends BaseModel {
           .snapshots()
           .listen((QuerySnapshot snapshot) {
             _boxes.clear();
-            _boxes = snapshot.documents.map((documentSnapshot) {
+            _boxes = snapshot.docs.map((documentSnapshot) {
               var s = Carton.fromMap(
-                  documentSnapshot.data, documentSnapshot.documentID);
+                  documentSnapshot.data() as Map<String, dynamic>,
+                  documentSnapshot.id);
               return s;
             }).toList();
             notifyListeners();
@@ -146,18 +147,18 @@ class CartonModel extends BaseModel {
   }
 
   Future<void> _loadCartonsByFilter(String orderName) async {
-    if (user == null || !user.hasCarton()) return null;
+    if (user == null || !user!.hasCarton()) return null;
     String path = "/$cartons_collection";
 
     try {
-      Query listenerQuery = Firestore.instance
+      Query listenerQuery = FirebaseFirestore.instance
           .collection("$path")
           .where("carton_type", whereIn: [
         carton_from_packages,
         carton_from_cartons
       ]).where("status", isEqualTo: carton_packed_status);
 
-      Query pageQuery = Firestore.instance
+      Query pageQuery = FirebaseFirestore.instance
           .collection("$path")
           .where("carton_type",
               whereIn: [carton_from_packages, carton_from_cartons])
@@ -171,10 +172,10 @@ class CartonModel extends BaseModel {
     }
   }
 
-  Paginator _getDelivered() {
-    if (user == null || !user.hasCarton()) return null;
+  Paginator? _getDelivered() {
+    if (user == null || !user!.hasCarton()) return null;
 
-    var pageQuery = Firestore.instance
+    var pageQuery = FirebaseFirestore.instance
         .collection("/$cartons_collection")
         .where("is_delivered", isEqualTo: true)
         .where("is_deleted", isEqualTo: false);
@@ -185,10 +186,10 @@ class CartonModel extends BaseModel {
   }
 
   Future<void> loadMore() async {
-    if (_delivered.ended || selectedIndex == 1) return;
+    if (_delivered == null && _delivered!.ended || selectedIndex == 1) return;
     isLoading = true;
     notifyListeners();
-    await _delivered.load(onFinished: () {
+    await _delivered!.load(onFinished: () {
       isLoading = false;
       notifyListeners();
     });
@@ -196,7 +197,7 @@ class CartonModel extends BaseModel {
 
   Future<void> refresh() async {
     if (selectedIndex == 1) return;
-    await _delivered.refresh(onFinished: () {
+    await _delivered?.refresh(onFinished: () {
       notifyListeners();
     });
   }
@@ -207,69 +208,62 @@ class CartonModel extends BaseModel {
 
   @override
   logout() async {
-    if (listener != null) await listener.cancel();
-    if (cartonListener != null) await cartonListener.cancel();
-    if (_delivered != null) _delivered.close();
+    if (listener != null) await listener!.cancel();
+    if (cartonListener != null) await cartonListener!.cancel();
+    if (_delivered != null) _delivered!.close();
     if (cartonsByFilter != null) cartonsByFilter.close();
     _boxes = [];
   }
 
   Future<List<Carton>> getCartons(String shipmentID) async {
     String path = "/$cartons_collection";
-    var querySnap = await Firestore.instance
+    var querySnap = await FirebaseFirestore.instance
         .collection(path)
         .where("shipment_id", isEqualTo: shipmentID)
-        .getDocuments();
-    return querySnap.documents
-        .map((e) => Carton.fromMap(e.data, e.documentID))
-        .toList();
+        .get();
+    return querySnap.docs.map((e) => Carton.fromMap(e.data(), e.id)).toList();
   }
 
   Future<List<Carton>> getCartonsByFcsShipment(String fcsShipmentID) async {
     String path = "/$cartons_collection";
-    var querySnap = await Firestore.instance
+    var querySnap = await FirebaseFirestore.instance
         .collection(path)
         .where("fcs_shipment_id", isEqualTo: fcsShipmentID)
         .where("is_deleted", isEqualTo: false)
-        .getDocuments();
-    return querySnap.documents
-        .map((e) => Carton.fromMap(e.data, e.documentID))
-        .toList();
+        .get();
+    return querySnap.docs.map((e) => Carton.fromMap(e.data(), e.id)).toList();
   }
 
   Future<List<Carton>> getCartonsForInvoice(
       String fcsShipmentID, String userID) async {
     String path = "/$cartons_collection";
-    var querySnap = await Firestore.instance
+    var querySnap = await FirebaseFirestore.instance
         .collection(path)
         .where("fcs_shipment_id", isEqualTo: fcsShipmentID)
         .where("user_id", isEqualTo: userID)
         .where("is_deleted", isEqualTo: false)
         .where("is_invoiced", isEqualTo: false)
-        .getDocuments();
-    List<Carton> cartons = querySnap.documents
-        .map((e) => Carton.fromMap(e.data, e.documentID))
-        .toList();
+        .get();
+    List<Carton> cartons =
+        querySnap.docs.map((e) => Carton.fromMap(e.data(), e.id)).toList();
     return cartons;
   }
 
   Future<List<Carton>> getMixCartonsByFcsShipment(String fcsShipmentID) async {
     String path = "/$cartons_collection";
-    var querySnap = await Firestore.instance
+    var querySnap = await FirebaseFirestore.instance
         .collection(path)
         .where("fcs_shipment_id", isEqualTo: fcsShipmentID)
         .where("carton_type", isEqualTo: carton_mix_box)
         .where("is_deleted", isEqualTo: false)
-        .getDocuments();
-    return querySnap.documents
-        .map((e) => Carton.fromMap(e.data, e.documentID))
-        .toList();
+        .get();
+    return querySnap.docs.map((e) => Carton.fromMap(e.data(), e.id)).toList();
   }
 
   Future<Carton> getCarton(String id) async {
     String path = "/$cartons_collection";
-    var snap = await Firestore.instance.collection(path).document(id).get();
-    return Carton.fromMap(snap.data, snap.documentID);
+    var snap = await FirebaseFirestore.instance.collection(path).doc(id).get();
+    return Carton.fromMap(snap.data() as Map<String, dynamic>, snap.id);
   }
 
   Future<Carton> createCarton(Carton carton) {