Begin making the Expense page more arbitrary for future re-use by creating superclasses which will fit all 3 object use cases.

lib/db.dart

@@ -1,45 +1,98 @@
 // https://docs.flutter.dev/cookbook/persistence/sqlite
 
 // SQLite
+import 'dart:io';
 import 'dart:async';
-import 'package:flutter/widgets.dart';
-import 'package:flutter_expense_tracker/models/frequency.dart';
 import 'package:path/path.dart';
+import 'package:path_provider/path_provider.dart';
 import 'package:sqflite/sqflite.dart';
 
 // Local
 import '/models/expense.dart';
 
-void loadDB() async {
+// Leaned on this example:
-  // Avoid errors caused by flutter upgrade.
+//   https://learnflutterwithme.com/sqlite
-  WidgetsFlutterBinding.ensureInitialized();
+class DatabaseHelper {
+  DatabaseHelper._privateConstructor();
+  static final DatabaseHelper instance = DatabaseHelper._privateConstructor();
 
-  final String frequencies =
+  static Database? _db;
-      "'${Frequency.values.map((freq) => freq.title).join("','")}'";
+  Future<Database> get db async => _db ??= await _initDatabase();
-  print(frequencies);
 
-  // Open the database and store the reference.
+  Future<Database> _initDatabase() async {
-  final database = openDatabase(
+    Directory documentsDirectory = await getApplicationDocumentsDirectory();
-    // Set the path to the database. Note: Using the `join` function from the
+    String path = join(documentsDirectory.path, "com_hyperling_expense.db");
-    // `path` package is best practice to ensure the path is correctly
+    return await openDatabase(
-    // constructed for each platform.
+      path,
-    join(await getDatabasesPath(), 'expense_tracker.db'),
+      version: 1,
+      onCreate: _onCreate,
+    );
+  }
 
-    onCreate: (db, version) {
+  Future _onCreate(Database db, int version) async {
-      // Run the CREATE TABLE statement on the database.
+    await db.execute("""
-      return db.execute(
-        """
         CREATE TABLE expense
           ( id INTEGER PRIMARY KEY
-          , name TEXT
+          , name TEXT NOT NULL UNIQUE
-          , cost DOUBLE
+          , cost DOUBLE NOT NULL
-          , frequency TEXT CHECK(frequency IN ($frequencies) )
+          , frequency TEXT NOT NULL
           , description TEXT
-        )""",
+        )
-      );
+        """);
-    },
+  }
-    // Set the version. This executes the onCreate function and provides a
+
-    // path to perform database upgrades and downgrades.
+  /// Expense Section
-    version: 1,
+  ///
-  );
+  Future<List<Expense>> getExpenses() async {
+    Database db = await instance.db;
+    var expenses = await db.query("expense", orderBy: "name");
+    List<Expense> expenseList = expenses.isNotEmpty
+        ? expenses.map((c) => Expense.fromMap(c)).toList()
+        : [];
+    return expenseList;
+  }
+
+  Future<int> addExpense(Expense expense) async {
+    Database db = await instance.db;
+    return await db.insert(
+      "expense",
+      expense.toMap(),
+    );
+  }
+
+  Future<int> removeExpense(int id) async {
+    Database db = await instance.db;
+    return await db.delete(
+      "expense",
+      where: "id = ?",
+      whereArgs: [id],
+    );
+  }
+
+  Future<int> updateExpense(Expense expense) async {
+    Database db = await instance.db;
+    return await db.update(
+      "expense",
+      expense.toMap(),
+      where: "id = ?",
+      whereArgs: [expense.id],
+    );
+  }
+
+  Future<bool> checkExpenseNameExists(String name) async {
+    Database db = await instance.db;
+    var expenses = await db.query("expense",
+        where: "name = ?", whereArgs: [name],);
+    return expenses.isNotEmpty;
+  }
+
+  ///
+
+  /// Income Section
+  ///
+
+  ///
+  /// Liquid Asset Section
+
+  ///
 }

lib/main.dart

@@ -2,16 +2,36 @@
 import 'package:flutter/material.dart';
 
 // Local
-import '/pages/expense.dart';
+import '/pages/home.dart';
-import '/pages/income.dart';
+
-import '/pages/asset.dart';
+// SQLite
-import '/pages/report.dart';
+import 'dart:io';
-import '/pages/settings.dart';
+import 'package:sqflite_common_ffi/sqflite_ffi.dart';
-import '/pages/help.dart';
+import 'package:path/path.dart';
-import '/db.dart';
+import 'package:path_provider/path_provider.dart';
+
+const bool testing = false;
 
 void main() {
-  loadDB();
+  // I see no good explanations of why to use this other package yet, but
+  // trying this to see if it fixes the DB factory errors.
+  // "Unhandled Exception: Bad state: databaseFactory not initialized databaseFactory is only initialized when using sqflite. When using `sqflite_common_ffi`You must call `databaseFactory = databaseFactoryFfi;` before using global openDatabase API
+  //   https://stackoverflow.com/questions/76158800/databasefactory-not-initialized-when-using-sqflite-in-flutter
+  if (Platform.isWindows || Platform.isLinux) {
+    // Initialize FFI
+    sqfliteFfiInit();
+    databaseFactory = databaseFactoryFfi;
+  }
+  WidgetsFlutterBinding.ensureInitialized();
+
+  if (testing) {
+    () async {
+    Directory documentsDirectory = await getApplicationDocumentsDirectory();
+    String path = join(documentsDirectory.path, 'com_hyperling_expense.db');
+      await deleteDatabase(path);
+    }();
+  }
+
   runApp(const MainApp());
 }
 
@@ -36,110 +56,3 @@ class MainApp extends StatelessWidget {
     );
   }
 }
-
-class HomePage extends StatefulWidget {
-  const HomePage({
-    super.key,
-  });
-
-  @override
-  State<HomePage> createState() => _HomePageState();
-}
-
-class _HomePageState extends State<HomePage> {
-  var pageSelected = 0;
-
-  refresh() {
-    setState(() {});
-  }
-
-  @override
-  Widget build(BuildContext context) {
-    Widget page;
-    Widget? dialog;
-    switch (pageSelected) {
-      case 0:
-        page = ExpensePage();
-        dialog = ExpenseInputDialog(
-          notifyParent: refresh,
-        );
-      case 1:
-        page = IncomePage();
-      case 2:
-        page = AssetPage();
-      case 3:
-        page = ProjectionPage();
-      case 4:
-        page = SettingsPage();
-      case 5:
-        page = HelpPage();
-      default:
-        throw UnimplementedError('No widget for page $pageSelected yet!');
-    }
-
-    Future<void> addNewValue(BuildContext context) {
-      return showDialog(
-        context: context,
-        builder: (_) => AlertDialog(content: dialog),
-      );
-    }
-
-    Widget? floatingButton;
-    if (dialog != null) {
-      floatingButton = IconButton(
-        onPressed: () {
-          addNewValue(context);
-        },
-        icon: Icon(Icons.add),
-        color: Theme.of(context).colorScheme.onSurface,
-      );
-    }
-
-    return LayoutBuilder(builder: (context, constraints) {
-      return Scaffold(
-        appBar: AppBar(title: Text("Expense Tracker")),
-        drawer: NavigationRail(
-          extended: true,
-          destinations: [
-            NavigationRailDestination(
-              icon: Icon(Icons.payment),
-              label: Text('Expenses'),
-            ),
-            NavigationRailDestination(
-              icon: Icon(Icons.account_balance),
-              label: Text('Income'),
-            ),
-            NavigationRailDestination(
-              icon: Icon(Icons.attach_money),
-              label: Text('Liquid Assets'),
-            ),
-            NavigationRailDestination(
-              icon: Icon(Icons.bar_chart),
-              label: Text('Reports'),
-            ),
-            NavigationRailDestination(
-              icon: Icon(Icons.settings),
-              label: Text('Settings'),
-            ),
-            NavigationRailDestination(
-              icon: Icon(Icons.help),
-              label: Text('Help'),
-            ),
-          ],
-          selectedIndex: pageSelected,
-          onDestinationSelected: (value) {
-            setState(() {
-              pageSelected = value;
-              Navigator.pop(context);
-            });
-          },
-        ),
-        body: Container(
-          color: Theme.of(context).colorScheme.primaryContainer,
-          child: Center(child: page),
-        ),
-        floatingActionButton: floatingButton,
-      );
-    });
-  }
-}

lib/models/expense.dart

@@ -1,27 +1,24 @@
+import '/models/recurring_tracked_type.dart';
 import '/models/frequency.dart';
 
-class Expense {
+class Expense extends RecurringTrackedType {
-  final String name;
+  static String amountText = "Cost";
-  final double cost;
-  final Frequency frequency;
-  final String description;
 
-  const Expense(
+  Expense({
-      {required this.name,
+    super.id,
-      required this.cost,
+    required super.name,
-      required this.frequency,
+    required super.amount,
-      required this.description});
+    required super.frequency,
+    required super.description,
+  });
 
-  @override
+  factory Expense.fromMap(Map<String, dynamic> json) => Expense(
-  String toString() {
+        id: json['id'],
-    return "$name, $cost, ${frequency.title}, $description";
+        name: json['name'],
-  }
+        amount: json['cost'],
-
+        frequency: Frequency.values
-  double calcComparableCost() {
+            .where((freq) => freq.title == json['frequency'])
-    return cost * frequency.timesPerYear;
+            .first,
-  }
+        description: json['description'],
-
+      );
-  double calcComparableCostDaily() {
-    return cost / frequency.numDays;
-  }
 }

lib/models/recurring_tracked_type.dart

@@ -0,0 +1,34 @@
+// Local
+import '/models/tracked_type.dart';
+import '/models/frequency.dart';
+
+abstract class RecurringTrackedType extends TrackedType {
+  Frequency frequency;
+
+  RecurringTrackedType({
+    super.id,
+    required super.name,
+    required super.amount,
+    required this.frequency,
+    required super.description,
+  });
+
+  double calcComparableAmountYearly() {
+    return amount * frequency.timesPerYear;
+  }
+
+  double calcComparableAmountDaily() {
+    return amount / frequency.numDays;
+  }
+
+  @override
+  Map<String, dynamic> toMap() {
+    return {
+      'id': id,
+      'name': name,
+      'amount': amount,
+      'frequency': frequency.title,
+      'description': description,
+    };
+  }
+}

lib/models/tracked_type.dart

@@ -0,0 +1,27 @@
+abstract class TrackedType {
+  int? id;
+  String name;
+  double amount;
+  String description;
+
+  TrackedType({
+    this.id,
+    required this.name,
+    required this.amount,
+    required this.description,
+  });
+
+  @override
+  String toString() {
+    return toMap().toString();
+  }
+
+  Map<String, dynamic> toMap() {
+    return {
+      'id': id,
+      'name': name,
+      'amount': amount,
+      'description': description,
+    };
+  }
+}

lib/pages/expense.dart

@@ -1,11 +1,12 @@
 // Flutter
 import 'package:flutter/material.dart';
+import 'package:flutter_expense_tracker/db.dart';
 
 // Local
 import '/models/expense.dart';
 import '/models/frequency.dart';
 
-List<Expense> expenses = [];
+// TODO: Make this a generic class based on a superclass of Expense, Income, and Assets?
 
 class ExpensePage extends StatefulWidget {
   const ExpensePage({
@@ -25,139 +26,156 @@ class _ExpensePageState extends State<ExpensePage> {
   Widget build(BuildContext context) {
     final theme = Theme.of(context);
 
-    expenses.sort(
+    return FutureBuilder<List<Expense>>(
-      (a, b) => (b.calcComparableCost() - a.calcComparableCost()).toInt(),
+        future: DatabaseHelper.instance.getExpenses(),
-    );
+        builder: (BuildContext context, AsyncSnapshot<List<Expense>> snapshot) {
-
+          if (!snapshot.hasData) {
-    return expenses.isEmpty
+            return Text('Loading...');
-        ? Text("Add expenses to get started!")
+          }
-        : ListView.builder(
+          snapshot.data!.sort(
-            itemCount: expenses.length,
+            (a, b) => (b.calcComparableAmountYearly() -
-            itemBuilder: (_, index) {
+                    a.calcComparableAmountYearly())
-              final Expense curr = expenses[index];
+                .toInt(),
-              final String estimateSymbolYearly = curr.frequency.timesPerYear
-                          .toStringAsFixed(2)
-                          .endsWith(".00") &&
-                      curr.calcComparableCost().toStringAsFixed(3).endsWith("0")
-                  ? ""
-                  : "~";
-              final String estimateSymbolDaily =
-                  curr.frequency.numDays.toStringAsFixed(2).endsWith(".00") &&
-                          curr
-                              .calcComparableCostDaily()
-                              .toStringAsFixed(3)
-                              .endsWith("0")
-                      ? ""
-                      : "~";
-              return Padding(
-                padding: const EdgeInsets.all(4.0),
-                child: Dismissible(
-                  key: Key(curr.toString()),
-                  background: Container(
-                    color: Colors.red,
-                    child: Row(
-                      mainAxisAlignment: MainAxisAlignment.start,
-                      children: [
-                        Icon(Icons.delete),
-                        Text("Delete"),
-                      ],
-                    ),
-                  ),
-                  secondaryBackground: Container(
-                    color: Colors.orange,
-                    child: Row(
-                      mainAxisAlignment: MainAxisAlignment.end,
-                      children: [
-                        Text("Edit"),
-                        Icon(Icons.edit),
-                      ],
-                    ),
-                  ),
-                  onDismissed: (direction) {
-                    setState(() {
-                      expenses.remove(curr);
-                    });
-                    switch (direction) {
-                      case DismissDirection.startToEnd:
-                        // Only remove the item from the list.
-                        break;
-                      case DismissDirection.endToStart:
-                        // Open an edit dialog, then remove the item from the list.
-                        showDialog(
-                          context: context,
-                          builder: (_) => AlertDialog(
-                            content: ExpenseInputDialog(
-                              notifyParent: refresh,
-                              expense: curr,
-                            ),
-                          ),
-                        );
-                        break;
-                      default:
-                        UnimplementedError(
-                          "Direction ${direction.toString()} not recognized.",
-                        );
-                    }
-                  },
-                  child: Container(
-                    decoration: BoxDecoration(
-                      borderRadius: BorderRadius.circular(4),
-                      color: theme.colorScheme.onPrimary,
-                    ),
-                    child: Padding(
-                      padding: const EdgeInsets.all(4.0),
-                      child: Row(
-                        mainAxisSize: MainAxisSize.max,
-                        children: [
-                          Column(
-                            mainAxisSize: MainAxisSize.min,
-                            crossAxisAlignment: CrossAxisAlignment.start,
-                            children: [
-                              Text(
-                                curr.name,
-                                style: TextStyle(fontSize: 20.0),
-                              ),
-                              Text(
-                                "${curr.cost.toStringAsFixed(2)} ${curr.frequency.title}",
-                                style: TextStyle(fontSize: 12.0),
-                              ),
-                            ],
-                          ),
-                          Expanded(
-                            child: Center(
-                              child: Text(
-                                curr.description,
-                                style: TextStyle(
-                                  fontSize: 12.0,
-                                ),
-                                softWrap: true,
-                                textAlign: TextAlign.center,
-                              ),
-                            ),
-                          ),
-                          Column(
-                            crossAxisAlignment: CrossAxisAlignment.end,
-                            children: [
-                              //if (curr.frequency != Frequency.daily)
-                              Text(
-                                "$estimateSymbolDaily${curr.calcComparableCostDaily().toStringAsFixed(2)} ${Frequency.daily.title}",
-                                style: TextStyle(fontSize: 12.0),
-                              ),
-                              //if (curr.frequency != Frequency.yearly)
-                              Text(
-                                "$estimateSymbolYearly${curr.calcComparableCost().toStringAsFixed(2)} ${Frequency.yearly.title}",
-                                style: TextStyle(fontSize: 12.0),
-                              ),
-                            ],
-                          ),
-                        ],
-                      ),
-                    ),
-                  ),
-                ),
-              );
-            },
           );
+          return snapshot.data!.isEmpty
+              ? Text(
+                  "Add expenses to get started.",
+                  softWrap: true,
+                )
+              : ListView.builder(
+                  itemCount: snapshot.data!.length,
+                  itemBuilder: (_, index) {
+                    List<Expense> expenses = snapshot.data!;
+                    final Expense curr = expenses[index];
+                    final String estimateSymbolYearly = curr
+                                .frequency.timesPerYear
+                                .toStringAsFixed(2)
+                                .endsWith(".00") &&
+                            curr
+                                .calcComparableAmountYearly()
+                                .toStringAsFixed(3)
+                                .endsWith("0")
+                        ? ""
+                        : "~";
+                    final String estimateSymbolDaily = curr.frequency.numDays
+                                .toStringAsFixed(2)
+                                .endsWith(".00") &&
+                            curr
+                                .calcComparableAmountDaily()
+                                .toStringAsFixed(3)
+                                .endsWith("0")
+                        ? ""
+                        : "~";
+                    return Padding(
+                      padding: const EdgeInsets.all(4.0),
+                      child: Dismissible(
+                        key: Key(curr.id!.toString()),
+                        background: Container(
+                          color: Colors.red,
+                          child: Row(
+                            mainAxisAlignment: MainAxisAlignment.start,
+                            children: [
+                              Icon(Icons.delete),
+                              Text("Delete"),
+                            ],
+                          ),
+                        ),
+                        secondaryBackground: Container(
+                          color: Colors.orange,
+                          child: Row(
+                            mainAxisAlignment: MainAxisAlignment.end,
+                            children: [
+                              Text("Edit"),
+                              Icon(Icons.edit),
+                            ],
+                          ),
+                        ),
+                        onDismissed: (direction) {
+                          setState(() {
+                            expenses.remove(curr);
+                            switch (direction) {
+                              case DismissDirection.startToEnd:
+                                DatabaseHelper.instance.removeExpense(curr.id!);
+                                break;
+                              case DismissDirection.endToStart:
+                                // Open an edit dialog, then remove the item from the list.
+                                showDialog(
+                                  context: context,
+                                  builder: (_) => AlertDialog(
+                                    content: ExpenseInputDialog(
+                                      notifyParent: refresh,
+                                      expense: curr,
+                                    ),
+                                  ),
+                                );
+                                break;
+                              default:
+                                UnimplementedError(
+                                  "Direction ${direction.toString()} not recognized.",
+                                );
+                            }
+                          });
+                        },
+                        child: Container(
+                          decoration: BoxDecoration(
+                            borderRadius: BorderRadius.circular(4),
+                            color: theme.colorScheme.onPrimary,
+                          ),
+                          child: Padding(
+                            padding: const EdgeInsets.all(4.0),
+                            child: Row(
+                              mainAxisSize: MainAxisSize.max,
+                              children: [
+                                Column(
+                                  mainAxisSize: MainAxisSize.min,
+                                  crossAxisAlignment: CrossAxisAlignment.start,
+                                  children: [
+                                    Text(
+                                      curr.name,
+                                      style: TextStyle(fontSize: 20.0),
+                                    ),
+                                    Text(
+                                      "${curr.amount.toStringAsFixed(2)} ${curr.frequency.title}",
+                                      style: TextStyle(fontSize: 12.0),
+                                    ),
+                                  ],
+                                ),
+                                Expanded(
+                                  child: Center(
+                                    child: Text(
+                                      curr.description,
+                                      style: TextStyle(
+                                        fontSize: 12.0,
+                                      ),
+                                      softWrap: true,
+                                      textAlign: TextAlign.center,
+                                    ),
+                                  ),
+                                ),
+                                Column(
+                                  crossAxisAlignment: CrossAxisAlignment.end,
+                                  children: [
+                                    //if (curr.frequency != Frequency.daily)
+                                    Text(
+                                      "$estimateSymbolDaily${curr.calcComparableAmountDaily().toStringAsFixed(2)} ${Frequency.daily.title}",
+                                      style: TextStyle(fontSize: 12.0),
+                                    ),
+                                    //if (curr.frequency != Frequency.yearly)
+                                    Text(
+                                      "$estimateSymbolYearly${curr.calcComparableAmountYearly().toStringAsFixed(2)} ${Frequency.yearly.title}",
+                                      style: TextStyle(fontSize: 12.0),
+                                    ),
+                                  ],
+                                ),
+                              ],
+                            ),
+                          ),
+                        ),
+                      ),
+                    );
+                  },
+                );
+        });
   }
 }
 
@@ -178,16 +196,18 @@ class ExpenseInputDialog extends StatefulWidget {
 class _ExpenseInputDialogState extends State<ExpenseInputDialog> {
   final _expenseFormKey = GlobalKey<FormState>();
 
+  int? _id;
   String _name = "";
-  double _cost = 0;
+  double _amount = 0;
   Frequency _freq = Frequency.monthly;
   String _desc = "";
 
   @override
   Widget build(BuildContext context) {
     if (widget.expense != null) {
+      _id = widget.expense!.id;
       _name = widget.expense!.name;
-      _cost = widget.expense!.cost;
+      _amount = widget.expense!.amount;
       _freq = widget.expense!.frequency;
       _desc = widget.expense!.description;
     }
@@ -202,7 +222,7 @@ class _ExpenseInputDialogState extends State<ExpenseInputDialog> {
             onPressed: () {
               if (widget.expense != null) {
                 setState(() {
-                  expenses.add(widget.expense!);
+                  DatabaseHelper.instance.addExpense(widget.expense!);
                   widget.notifyParent();
                 });
               }
@@ -218,122 +238,134 @@ class _ExpenseInputDialogState extends State<ExpenseInputDialog> {
                 ? Text("New Expense")
                 : Text("Edit Expense"),
           ),
-          content: Form(
+          content: FutureBuilder<List<Expense>>(
-            key: _expenseFormKey,
+              future: DatabaseHelper.instance.getExpenses(),
-            child: Column(
+              builder: (BuildContext context,
-              mainAxisSize: MainAxisSize.min,
+                  AsyncSnapshot<List<Expense>> snapshot) {
-              children: [
+                if (!snapshot.hasData) {
-                TextFormField(
+                  return Center(child: Text('Loading...'));
-                  keyboardType: TextInputType.text,
+                }
-                  textCapitalization: TextCapitalization.words,
+                List<Expense> expenses = snapshot.data!;
-                  decoration: InputDecoration(
+                return Form(
-                    labelText: "Name",
+                  key: _expenseFormKey,
-                    hintText: "Example: Red Pocket",
+                  child: Column(
-                    hintStyle: TextStyle(fontSize: 10.0),
+                    mainAxisSize: MainAxisSize.min,
-                    errorStyle: TextStyle(fontSize: 10.0),
+                    children: [
-                  ),
+                      TextFormField(
-                  initialValue: _name,
+                        keyboardType: TextInputType.text,
-                  validator: (value) {
+                        textCapitalization: TextCapitalization.words,
-                    if (value!.isEmpty) {
+                        decoration: InputDecoration(
-                      return "Name must be provided.";
+                          labelText: "Name",
-                    }
+                          hintText: "Example: Red Pocket",
-                    if (!expenses.every((expense) => expense.name != value)) {
+                          hintStyle: TextStyle(fontSize: 10.0),
-                      return "Name must be unique, already in use.";
+                          errorStyle: TextStyle(fontSize: 10.0),
-                    }
+                        ),
-                    return null;
+                        initialValue: _name,
-                  },
+                        validator: (value) {
-                  onSaved: (value) {
+                          if (value!.isEmpty) {
-                    _name = value!;
+                            return "Name must be provided.";
-                  },
+                          }
-                ),
+                          if (!expenses.every((expense) =>
-                TextFormField(
+                              expense.name != value || expense.id == _id)) {
-                  keyboardType: TextInputType.numberWithOptions(decimal: true),
+                            return "Name must be unique, already in use.";
-                  decoration: InputDecoration(
+                          }
-                    labelText: "Cost",
+                          return null;
-                    hintText: "Example: 10.00",
+                        },
-                    hintStyle: TextStyle(fontSize: 10.0),
+                        onSaved: (value) {
-                    errorStyle: TextStyle(fontSize: 10.0),
+                          _name = value!;
-                  ),
+                        },
-                  initialValue: _cost != 0 ? _cost.toString() : "",
+                      ),
-                  validator: (value) {
+                      TextFormField(
-                    if (value == null || value.isEmpty) {
+                        keyboardType:
-                      return "Cost must be provided.";
+                            TextInputType.numberWithOptions(decimal: true),
-                    }
+                        decoration: InputDecoration(
-                    if (double.parse(value) < 0) {
+                          labelText: "${Expense.amountText}",
-                      return "Please use the Income page rather than having negative expenses.";
+                          hintText: "Example: 10.00",
-                    }
+                          hintStyle: TextStyle(fontSize: 10.0),
-                    if (double.parse(value) < 0.01) {
+                          errorStyle: TextStyle(fontSize: 10.0),
-                      return "Cost must be one hundreth (0.01) or higher.";
+                        ),
-                    }
+                        initialValue: _amount != 0 ? _amount.toString() : "",
-                    if (double.tryParse(value) == null) {
+                        validator: (value) {
-                      return "Cost must be a valid number.";
+                          if (value == null || value.isEmpty) {
-                    }
+                            return "${Expense.amountText} must be provided.";
-                    return null;
+                          }
-                  },
+                          if (double.parse(value) < 0) {
-                  onSaved: (value) {
+                            return "Please use the Income page rather than having negative expenses.";
-                    _cost = double.parse(value!);
+                          }
-                  },
+                          if (double.parse(value) < 0.01) {
-                ),
+                            return "${Expense.amountText} must be one hundreth (0.01) or higher.";
-                DropdownButtonFormField(
+                          }
-                  items: Frequency.values
+                          if (double.tryParse(value) == null) {
-                      .map(
+                            return "${Expense.amountText} must be a valid number.";
-                        (freq) => DropdownMenuItem(
+                          }
-                          value: freq,
+                          return null;
-                          child: Row(
+                        },
-                            children: [
+                        onSaved: (value) {
-                              Text(
+                          _amount = double.parse(value!);
-                                freq.title,
+                        },
-                              ),
+                      ),
-                              Padding(
+                      DropdownButtonFormField(
-                                padding: EdgeInsets.all(1.0),
+                        items: Frequency.values
-                                child: Text(
+                            .map(
-                                  " (${freq.hint})",
+                              (freq) => DropdownMenuItem(
-                                  style: TextStyle(fontSize: 10.0),
+                                value: freq,
+                                child: Row(
+                                  children: [
+                                    Text(
+                                      freq.title,
+                                    ),
+                                    Padding(
+                                      padding: EdgeInsets.all(1.0),
+                                      child: Text(
+                                        " (${freq.hint})",
+                                        style: TextStyle(fontSize: 10.0),
+                                      ),
+                                    ),
+                                  ],
                                 ),
                               ),
-                            ],
+                            )
-                          ),
+                            .toList(),
+                        value: _freq,
+                        decoration: InputDecoration(
+                          labelText: "Frequency",
+                          errorStyle: TextStyle(fontSize: 10.0),
                         ),
-                      )
+                        validator: (value) {
-                      .toList(),
+                          if (value == null) {
-                  value: _freq,
+                            return "Frequency must be provided.";
-                  decoration: InputDecoration(
+                          }
-                    labelText: "Frequency",
+                          if (!Frequency.values.contains(value)) {
-                    errorStyle: TextStyle(fontSize: 10.0),
+                            return "Value not valid.";
+                          }
+                          return null;
+                        },
+                        onChanged: (value) {
+                          _freq = value!;
+                        },
+                      ),
+                      TextFormField(
+                        keyboardType: TextInputType.text,
+                        textCapitalization: TextCapitalization.sentences,
+                        decoration: InputDecoration(
+                          labelText: "Description",
+                          hintText:
+                              "Example: 1GB data with unlimited talk & text.",
+                          hintStyle: TextStyle(fontSize: 8.0),
+                          errorStyle: TextStyle(fontSize: 10.0),
+                        ),
+                        initialValue: _desc,
+                        validator: (value) {
+                          return null;
+                        },
+                        onSaved: (value) {
+                          _desc = value!;
+                        },
+                      ),
+                    ],
                   ),
-                  validator: (value) {
+                );
-                    if (value == null) {
+              }),
-                      return "Frequency must be provided.";
-                    }
-                    if (!Frequency.values.contains(value)) {
-                      return "Value not valid.";
-                    }
-                    return null;
-                  },
-                  onChanged: (value) {
-                    _freq = value!;
-                  },
-                ),
-                TextFormField(
-                  keyboardType: TextInputType.text,
-                  textCapitalization: TextCapitalization.sentences,
-                  decoration: InputDecoration(
-                    labelText: "Description",
-                    hintText: "Example: 1GB data with unlimited talk & text.",
-                    hintStyle: TextStyle(fontSize: 8.0),
-                    errorStyle: TextStyle(fontSize: 10.0),
-                  ),
-                  initialValue: _desc,
-                  validator: (value) {
-                    return null;
-                  },
-                  onSaved: (value) {
-                    _desc = value!;
-                  },
-                ),
-              ],
-            ),
-          ),
           actions: [
             Center(
               child: ElevatedButton.icon(
@@ -341,13 +373,22 @@ class _ExpenseInputDialogState extends State<ExpenseInputDialog> {
                   if (_expenseFormKey.currentState!.validate()) {
                     _expenseFormKey.currentState!.save();
                     setState(() {
-                      expenses.add(
+                      Expense expense = Expense(
-                        Expense(
+                        id: _id,
-                            name: _name,
+                        name: _name,
-                            cost: _cost,
+                        amount: _amount,
-                            frequency: _freq,
+                        frequency: _freq,
-                            description: _desc),
+                        description: _desc,
                       );
+                      if (_id != null) {
+                        DatabaseHelper.instance.updateExpense(
+                          expense,
+                        );
+                      } else {
+                        DatabaseHelper.instance.addExpense(
+                          expense,
+                        );
+                      }
                     });
                     widget.notifyParent();
                     Navigator.of(context).pop();

lib/pages/home.dart

@@ -0,0 +1,140 @@
+// Flutter
+import 'package:flutter/material.dart';
+import 'dart:io';
+
+// Local
+import '/pages/expense.dart';
+import '/pages/income.dart';
+import '/pages/asset.dart';
+import '/pages/report.dart';
+import '/pages/settings.dart';
+import '/pages/help.dart';
+
+class HomePage extends StatefulWidget {
+  const HomePage({
+    super.key,
+  });
+
+  @override
+  State<HomePage> createState() => _HomePageState();
+}
+
+class _HomePageState extends State<HomePage> {
+  var pageSelected = 0;
+
+  refresh() {
+    setState(() {});
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    Widget page;
+    Widget? dialog;
+    switch (pageSelected) {
+      case 0:
+        page = ExpensePage();
+        dialog = ExpenseInputDialog(
+          notifyParent: refresh,
+        );
+      case 1:
+        page = IncomePage();
+      case 2:
+        page = AssetPage();
+      case 3:
+        page = ProjectionPage();
+      case 4:
+        page = SettingsPage();
+      case 5:
+        page = HelpPage();
+      default:
+        throw UnimplementedError('No widget for page $pageSelected yet!');
+    }
+
+    Future<void> addNewValue(BuildContext context) {
+      return showDialog(
+        context: context,
+        builder: (_) => AlertDialog(content: dialog),
+      );
+    }
+
+    Widget? floatingButton;
+    if (dialog != null) {
+      floatingButton = IconButton(
+        onPressed: () {
+          addNewValue(context);
+        },
+        icon: Icon(Icons.add),
+        color: Theme.of(context).colorScheme.onSurface,
+      );
+    }
+
+    Widget navigation = NavigationRail(
+      extended: true,
+      destinations: [
+        NavigationRailDestination(
+          icon: Icon(Icons.payment),
+          label: Text('Expenses'),
+        ),
+        NavigationRailDestination(
+          icon: Icon(Icons.account_balance),
+          label: Text('Income'),
+        ),
+        NavigationRailDestination(
+          icon: Icon(Icons.attach_money),
+          label: Text('Liquid Assets'),
+        ),
+        NavigationRailDestination(
+          icon: Icon(Icons.bar_chart),
+          label: Text('Reports'),
+        ),
+        NavigationRailDestination(
+          icon: Icon(Icons.settings),
+          label: Text('Settings'),
+        ),
+        NavigationRailDestination(
+          icon: Icon(Icons.help),
+          label: Text('Help'),
+        ),
+      ],
+      selectedIndex: pageSelected,
+      onDestinationSelected: (value) {
+        setState(() {
+          pageSelected = value;
+          if (Platform.isAndroid || Platform.isIOS) {
+            Navigator.pop(context);
+          }
+        });
+      },
+    );
+
+    Widget main = Container(
+      color: Theme.of(context).colorScheme.primaryContainer,
+      child: Center(child: page),
+    );
+
+    Widget? drawer, body;
+    if (Platform.isAndroid || Platform.isIOS) {
+      drawer = navigation;
+      body = main;
+    } else {
+      drawer = null;
+      body = Row(
+        children: [
+          SafeArea(child: navigation),
+          Expanded(child: main),
+        ],
+      );
+    }
+
+    return LayoutBuilder(builder: (context, constraints) {
+      return Scaffold(
+        appBar: AppBar(
+          title: Text("Expense Tracker"),
+        ),
+        drawer: drawer,
+        body: body,
+        floatingActionButton: floatingButton,
+      );
+    });
+  }
+}

macos/Flutter/GeneratedPluginRegistrant.swift

@@ -5,8 +5,10 @@
 import FlutterMacOS
 import Foundation
 
+import path_provider_foundation
 import sqflite_darwin
 
 func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
+  PathProviderPlugin.register(with: registry.registrar(forPlugin: "PathProviderPlugin"))
   SqflitePlugin.register(with: registry.registrar(forPlugin: "SqflitePlugin"))
 }

pubspec.lock

@@ -49,6 +49,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.3.1"
+  ffi:
+    dependency: transitive
+    description:
+      name: ffi
+      sha256: "16ed7b077ef01ad6170a3d0c57caa4a112a38d7a2ed5602e0aca9ca6f3d98da6"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.1.3"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -124,13 +132,61 @@ packages:
     source: hosted
     version: "1.15.0"
   path:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: path
       sha256: "087ce49c3f0dc39180befefc60fdb4acd8f8620e5682fe2476afd0b3688bb4af"
       url: "https://pub.dev"
     source: hosted
     version: "1.9.0"
+  path_provider:
+    dependency: "direct main"
+    description:
+      name: path_provider
+      sha256: "50c5dd5b6e1aaf6fb3a78b33f6aa3afca52bf903a8a5298f53101fdaee55bbcd"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.1.5"
+  path_provider_android:
+    dependency: transitive
+    description:
+      name: path_provider_android
+      sha256: "4adf4fd5423ec60a29506c76581bc05854c55e3a0b72d35bb28d661c9686edf2"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.2.15"
+  path_provider_foundation:
+    dependency: transitive
+    description:
+      name: path_provider_foundation
+      sha256: "4843174df4d288f5e29185bd6e72a6fbdf5a4a4602717eed565497429f179942"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.1"
+  path_provider_linux:
+    dependency: transitive
+    description:
+      name: path_provider_linux
+      sha256: f7a1fe3a634fe7734c8d3f2766ad746ae2a2884abe22e241a8b301bf5cac3279
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.2.1"
+  path_provider_platform_interface:
+    dependency: transitive
+    description:
+      name: path_provider_platform_interface
+      sha256: "88f5779f72ba699763fa3a3b06aa4bf6de76c8e5de842cf6f29e2e06476c2334"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.1.2"
+  path_provider_windows:
+    dependency: transitive
+    description:
+      name: path_provider_windows
+      sha256: bd6f00dbd873bfb70d0761682da2b3a2c2fccc2b9e84c495821639601d81afe7
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.3.0"
   platform:
     dependency: transitive
     description:
@@ -184,6 +240,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.5.4+6"
+  sqflite_common_ffi:
+    dependency: "direct main"
+    description:
+      name: sqflite_common_ffi
+      sha256: "883dd810b2b49e6e8c3b980df1829ef550a94e3f87deab5d864917d27ca6bf36"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.3.4+4"
   sqflite_darwin:
     dependency: transitive
     description:
@@ -200,6 +264,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.4.0"
+  sqlite3:
+    dependency: transitive
+    description:
+      name: sqlite3
+      sha256: "35d3726fe18ab1463403a5cc8d97dbc81f2a0b08082e8173851363fcc97b6627"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.7.2"
   stack_trace:
     dependency: transitive
     description:
@@ -248,6 +320,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.7.3"
+  typed_data:
+    dependency: transitive
+    description:
+      name: typed_data
+      sha256: f9049c039ebfeb4cf7a7104a675823cd72dba8297f264b6637062516699fa006
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.4.0"
   vector_math:
     dependency: transitive
     description:
@@ -264,6 +344,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "14.3.0"
+  web:
+    dependency: transitive
+    description:
+      name: web
+      sha256: cd3543bd5798f6ad290ea73d210f423502e71900302dde696f8bff84bf89a1cb
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.0"
+  xdg_directories:
+    dependency: transitive
+    description:
+      name: xdg_directories
+      sha256: "7a3f37b05d989967cdddcbb571f1ea834867ae2faa29725fd085180e0883aa15"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.0"
 sdks:
   dart: ">=3.6.1 <4.0.0"
   flutter: ">=3.24.0"

pubspec.yaml

@@ -9,7 +9,10 @@ environment:
 dependencies:
   flutter:
     sdk: flutter
+  path: ^1.9.0
+  path_provider: ^2.1.5
   sqflite: ^2.4.1
+  sqflite_common_ffi: ^2.3.4+4
 
 dev_dependencies:
   flutter_test: