check null safety

lib/pages/rates/cargo_editor.dart

@@ -31,7 +31,7 @@ class _CargoEditorState extends State<CargoEditor> {
     super.initState();
     if (widget.cargo != null) {
       _cargo = widget.cargo!;
-      _descController.text = _cargo.name;
+      _descController.text = _cargo.name ?? "";
       _rateController.text = _cargo.rate.toStringAsFixed(2);
     } else {
       _isNew = true;
@@ -138,7 +138,7 @@ class _CargoEditorState extends State<CargoEditor> {
     try {
       var shipmentRateModel =
           Provider.of<ShipmentRateModel>(context, listen: false);
-      await shipmentRateModel.deleteCargoType(this._cargo.id);
+      await shipmentRateModel.deleteCargoType(this._cargo.id!);
       Navigator.pop(context);
     } catch (e) {
       showMsgDialog(context, "Error", e.toString());

lib/pages/rates/cargo_type_list.dart

@@ -75,7 +75,7 @@ class _CargoTypeListState extends State<CargoTypeList> {
                               )));
                     },
                     child: Container(
-                      child: _row(cargo.name,
+                      child: _row(cargo.name ?? "",
                           "\$ " + cargo.rate.toStringAsFixed(2), 'per pound'),
                     ),
                   );

lib/pages/rates/custom_editor.dart

@@ -33,7 +33,7 @@ class _CustomEditorState extends State<CustomEditor> {
     super.initState();
     if (widget.custom != null) {
       _custom = widget.custom!;
-      _productController.text = _custom.name;
+      _productController.text = _custom.name??"";
       _feeController.text = _custom.customDutyFee.toStringAsFixed(2);
       _shipmentRateController.text =
           _custom.rate == null ? "" : _custom.rate.toStringAsFixed(2);
@@ -154,7 +154,7 @@ class _CustomEditorState extends State<CustomEditor> {
     try {
       var shipmentRateModel =
           Provider.of<ShipmentRateModel>(context, listen: false);
-      await shipmentRateModel.deleteCustomDuty(this._custom.id);
+      await shipmentRateModel.deleteCustomDuty(this._custom.id!);
       Navigator.pop(context);
     } catch (e) {
       showMsgDialog(context, "Error", e.toString());

lib/pages/rates/custom_list.dart

@@ -81,7 +81,7 @@ class _CustomListState extends State<CustomList> {
                     },
                     child: Container(
                       child: _row(
-                          custom.name,
+                          custom.name??"",
                           "Custom Fee \$ " + custom.customDutyFee.toStringAsFixed(2),
                           custom.rate == null
                               ? ""

lib/pages/rates/custom_row.dart

@@ -1,9 +1,9 @@
 import 'package:fcs/domain/entities/custom_duty.dart';
-import 'package:fcs/domain/vo/delivery_address.dart';
 import 'package:fcs/helpers/theme.dart';
 import 'package:fcs/pages/widgets/local_text.dart';
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter_icons_null_safety/flutter_icons_null_safety.dart';
 
 typedef SelectionCallback(CustomDuty custom);
 

lib/pages/rates/discount_by_weight_editor.dart

@@ -143,7 +143,7 @@ class _DiscountByWeightEditorState extends State<DiscountByWeightEditor> {
       var shipmentRateModel =
           Provider.of<ShipmentRateModel>(context, listen: false);
       await shipmentRateModel
-          .deleteDiscountByWeight(this._discountByWeight.id);
+          .deleteDiscountByWeight(this._discountByWeight.id!);
       Navigator.pop(context);
     } catch (e) {
       showMsgDialog(context, "Error", e.toString());

lib/pages/rates/model/shipment_rate_model.dart

@@ -2,7 +2,6 @@ import 'dart:async';
 
 import 'package:fcs/data/services/services.dart';
 import 'package:fcs/domain/entities/cargo_type.dart';
-import 'package:fcs/domain/entities/custom_duty.dart';
 import 'package:fcs/domain/entities/discount_by_weight.dart';
 import 'package:fcs/domain/entities/rate.dart';
 import 'package:fcs/pages/main/model/base_model.dart';
@@ -11,12 +10,12 @@ import 'package:logging/logging.dart';
 class ShipmentRateModel extends BaseModel {
   final log = Logger('ShipmentRateModel');
 
-  StreamSubscription<Rate> listener;
-  Rate rate;
+  StreamSubscription<Rate>? listener;
+  late Rate rate;
 
   void initUser(user) {
     super.initUser(user);
-    if (listener != null) listener.cancel();
+    if (listener != null) listener!.cancel();
     listener = Services.instance.rateService.getRateStream().listen((rate) {
       this.rate = rate;
       notifyListeners();
@@ -25,7 +24,7 @@ class ShipmentRateModel extends BaseModel {
 
   @override
   logout() async {
-    if (listener != null) await listener.cancel();
+    if (listener != null) await listener!.cancel();
   }
 
   // Rate
@@ -51,12 +50,12 @@ class ShipmentRateModel extends BaseModel {
   //CustomDuty
 
   Future<void> addCustomDuty(CargoType customDuty) {
-    customDuty.isCutomDuty=true;
+    customDuty.isCutomDuty = true;
     return Services.instance.rateService.createCargoType(customDuty);
   }
 
   Future<void> updateCustomDuty(CargoType customDuty) {
-    customDuty.isCutomDuty=true;
+    customDuty.isCutomDuty = true;
     return Services.instance.rateService.updateCargoType(customDuty);
   }
 

lib/pages/rates/shipment_rates.dart

@@ -1,5 +1,4 @@
 import 'package:fcs/domain/entities/cargo_type.dart';
-import 'package:fcs/domain/entities/custom_duty.dart';
 import 'package:fcs/domain/entities/discount_by_weight.dart';
 import 'package:fcs/domain/entities/rate.dart';
 import 'package:fcs/helpers/theme.dart';
@@ -185,8 +184,8 @@ class _ShipmentRatesState extends State<ShipmentRates> {
   List<Widget> getCargoWidget(List<CargoType> cargos) {
     return cargos.map((cargo) {
       return Container(
-        child: _row(
-            cargo.name, "\$ " + cargo.rate.toStringAsFixed(2), 'per pound'),
+        child: _row(cargo.name ?? "", "\$ " + cargo.rate.toStringAsFixed(2),
+            'per pound'),
       );
     }).toList();
   }
@@ -194,7 +193,8 @@ class _ShipmentRatesState extends State<ShipmentRates> {
   List<Widget> getCustonWidget(List<CargoType> customs) {
     return customs.map((c) {
       return Container(
-        child: _row(c.name, "\$ " + c.customDutyFee.toStringAsFixed(2), ''),
+        child:
+            _row(c.name ?? "", "\$ " + c.customDutyFee.toStringAsFixed(2), ''),
       );
     }).toList();
   }

lib/pages/rates/shipment_rates_calculate.dart

@@ -11,6 +11,7 @@ import 'package:fcs/pages/widgets/local_text.dart';
 import 'package:fcs/pages/widgets/progress.dart';
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter_icons_null_safety/flutter_icons_null_safety.dart';
 import 'package:provider/provider.dart';
 
 class ShipmentRatesCal extends StatefulWidget {

lib/pages/rates/shipment_rates_edit.dart

@@ -35,12 +35,11 @@ class _ShipmentRatesEditState extends State<ShipmentRatesEdit> {
         Provider.of<ShipmentRateModel>(context, listen: false);
     rate = shipmentRateModel.rate;
 
-    _minWeight.text = rate.freeDeliveryWeight?.toStringAsFixed(2) ?? "";
-    _deliveryFee.text = rate.deliveryFee?.toStringAsFixed(2) ?? "";
-    _volumetricRatio.text = rate.volumetricRatio?.toStringAsFixed(2) ?? "";
-    _diffDiscountWeight.text =
-        rate.diffDiscountWeight?.toStringAsFixed(2) ?? "";
-    _diffWeightRate.text = rate.diffWeightRate?.toStringAsFixed(2) ?? "";
+    _minWeight.text = rate.freeDeliveryWeight.toStringAsFixed(2);
+    _deliveryFee.text = rate.deliveryFee.toStringAsFixed(2);
+    _volumetricRatio.text = rate.volumetricRatio.toStringAsFixed(2);
+    _diffDiscountWeight.text = rate.diffDiscountWeight.toStringAsFixed(2);
+    _diffWeightRate.text = rate.diffWeightRate.toStringAsFixed(2);
   }
 
   @override