add pagination for pages

lib/pages/staff/model/staff_model.dart

@@ -9,53 +9,47 @@ import 'package:fcs/helpers/firebase_helper.dart';
 import 'package:fcs/pages/main/model/base_model.dart';
 import 'package:logging/logging.dart';
 
+import '../../../pagination/paginator_listener.dart';
+
 class StaffModel extends BaseModel {
   final log = Logger('StaffModel');
-  StreamSubscription<QuerySnapshot>? listener;
-  StreamSubscription<QuerySnapshot>? privilegeListener;
+  PaginatorListener<User>? getStaffs;
 
-  List<User> employees = [];
+  StreamSubscription<QuerySnapshot>? privilegeListener;
   List<Privilege> privileges = [];
 
   @override
   void privilegeChanged() {
     super.privilegeChanged();
     _loadPrivileges();
-    _loadEmployees();
   }
 
   @override
   logout() async {
-    if (listener != null) listener!.cancel();
+    getStaffs?.close();
     if (privilegeListener != null) privilegeListener!.cancel();
-    employees = [];
     privileges = [];
   }
 
-  Future<void> _loadEmployees() async {
+  loadPaginationStaffs() {
     if (user == null || !user!.hasStaffs()) return;
 
-    try {
-      if (listener != null) listener!.cancel();
+    String path = "/$user_collection";
+    Query col = FirebaseFirestore.instance
+        .collection(path)
+        .where("is_employee", isEqualTo: true)
+        .where("is_sys_admin", isEqualTo: false);
 
-      listener = FirebaseFirestore.instance
-          .collection("/$user_collection")
-          .where("is_employee", isEqualTo: true)
-          .where("is_sys_admin", isEqualTo: false)
-          .snapshots()
-          .listen((QuerySnapshot snapshot) {
-        employees.clear();
-        employees = snapshot.docs.map((documentSnapshot) {
-          var user = User.fromMap(
-              documentSnapshot.data() as Map<String, dynamic>,
-              documentSnapshot.id);
-          return user;
-        }).toList();
-        notifyListeners();
-      });
-    } catch (e) {
-      log.warning("Error!! $e");
-    }
+    Query pageQuery = FirebaseFirestore.instance
+        .collection(path)
+        .where("is_employee", isEqualTo: true)
+        .where("is_sys_admin", isEqualTo: false)
+        .orderBy("update_time", descending: true);
+
+    getStaffs?.close();
+    getStaffs = PaginatorListener<User>(
+        col, pageQuery, (data, id) => User.fromMap(data, id),
+        rowPerLoad: 30);
   }
 
   Future<void> _loadPrivileges() async {

lib/pages/staff/staff_list.dart

@@ -9,6 +9,7 @@ import 'package:flutter_vector_icons/flutter_vector_icons.dart';
 import 'package:intl/intl.dart';
 import 'package:provider/provider.dart';
 
+import '../../pagination/paginator_listview.dart';
 import 'staff_editor.dart';
 
 class StaffList extends StatefulWidget {
@@ -21,6 +22,12 @@ class _StaffListState extends State<StaffList> {
   final double dotSize = 15.0;
   bool _isLoading = false;
 
+  @override
+  void initState() {
+    context.read<StaffModel>().loadPaginationStaffs();
+    super.initState();
+  }
+
   @override
   Widget build(BuildContext context) {
     StaffModel staffModel = Provider.of<StaffModel>(context);
@@ -28,42 +35,33 @@ class _StaffListState extends State<StaffList> {
     return LocalProgress(
       inAsyncCall: _isLoading,
       child: Scaffold(
-        appBar: AppBar(
-          centerTitle: true,
-          leading: new IconButton(
-            icon: new Icon(CupertinoIcons.back),
-            onPressed: () => Navigator.of(context).pop(),
+          appBar: AppBar(
+            centerTitle: true,
+            leading: new IconButton(
+              icon: new Icon(CupertinoIcons.back),
+              onPressed: () => Navigator.of(context).pop(),
+            ),
+            backgroundColor: primaryColor,
+            title: LocalText(
+              context,
+              'staff.list.title',
+              color: Colors.white,
+              fontSize: 20,
+            ),
           ),
-          backgroundColor: primaryColor,
-          title: LocalText(
-            context,
-            'staff.list.title',
-            color: Colors.white,
-            fontSize: 20,
+          floatingActionButton: FloatingActionButton.extended(
+            onPressed: () {
+              Navigator.of(context).push(
+                  CupertinoPageRoute(builder: (context) => StaffEditor()));
+            },
+            icon: Icon(Icons.add),
+            label: LocalText(context, "staff.new", color: Colors.white),
+            backgroundColor: primaryColor,
           ),
-        ),
-        floatingActionButton: FloatingActionButton.extended(
-          onPressed: () {
-            Navigator.of(context)
-                .push(CupertinoPageRoute(builder: (context) => StaffEditor()));
-          },
-          icon: Icon(Icons.add),
-          label: LocalText(context, "staff.new", color: Colors.white),
-          backgroundColor: primaryColor,
-        ),
-        body: new ListView.separated(
-            separatorBuilder: (context, index) => Divider(
-                  color: Colors.black,
-                  height: 1,
-                ),
-            scrollDirection: Axis.vertical,
-            shrinkWrap: true,
-            itemCount: staffModel.employees.length,
-            itemBuilder: (BuildContext context, int index) {
-              User user = staffModel.employees[index];
-              return _item(user);
-            }),
-      ),
+          body: PaginatorListView<User>(
+              paginatorListener: staffModel.getStaffs!,
+              rowBuilder: (p) => _item(p),
+              color: primaryColor)),
     );
   }