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

lib/models/expense.dart

@@ -1,51 +1,24 @@
+import '/models/recurring_tracked_type.dart';
 import '/models/frequency.dart';
 
-class Expense {
+class Expense extends RecurringTrackedType {
-  final int? id;
+  static String amountText = "Cost";
-  final String name;
-  final double cost;
-  final Frequency frequency;
-  final String description;
 
-  const Expense({
+  Expense({
-    this.id,
+    super.id,
-    required this.name,
+    required super.name,
-    required this.cost,
+    required super.amount,
-    required this.frequency,
+    required super.frequency,
-    required this.description,
+    required super.description,
   });
 
-  @override
-  String toString() {
-    //return "$name, $cost, ${frequency.title}, $description";
-    return toMap().toString();
-  }
-
-  double calcComparableCost() {
-    return cost * frequency.timesPerYear;
-  }
-
-  double calcComparableCostDaily() {
-    return cost / frequency.numDays;
-  }
-
   factory Expense.fromMap(Map<String, dynamic> json) => Expense(
         id: json['id'],
         name: json['name'],
-        cost: json['cost'],
+        amount: json['cost'],
         frequency: Frequency.values
-            .where((expense) => expense.title == json['frequency'])
+            .where((freq) => freq.title == json['frequency'])
             .first,
         description: json['description'],
       );
-
-  Map<String, dynamic> toMap() {
-    return {
-      'id': id,
-      'name': name,
-      'cost': cost,
-      'frequency': frequency.title,
-      'description': description,
-    };
-  }
 }

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

@@ -6,7 +6,7 @@ import 'package:flutter_expense_tracker/db.dart';
 import '/models/expense.dart';
 import '/models/frequency.dart';
 
-// TODO: Make this a generic class based on a suerclass of Expense, Income, and Assets?
+// TODO: Make this a generic class based on a superclass of Expense, Income, and Assets?
 
 class ExpensePage extends StatefulWidget {
   const ExpensePage({
@@ -30,10 +30,12 @@ class _ExpensePageState extends State<ExpensePage> {
         future: DatabaseHelper.instance.getExpenses(),
         builder: (BuildContext context, AsyncSnapshot<List<Expense>> snapshot) {
           if (!snapshot.hasData) {
-            return Center(child: Text('Loading...'));
+            return Text('Loading...');
           }
           snapshot.data!.sort(
-            (a, b) => (b.calcComparableCost() - a.calcComparableCost()).toInt(),
+            (a, b) => (b.calcComparableAmountYearly() -
+                    a.calcComparableAmountYearly())
+                .toInt(),
           );
           return snapshot.data!.isEmpty
               ? Text(
@@ -50,7 +52,7 @@ class _ExpensePageState extends State<ExpensePage> {
                                 .toStringAsFixed(2)
                                 .endsWith(".00") &&
                             curr
-                                .calcComparableCost()
+                                .calcComparableAmountYearly()
                                 .toStringAsFixed(3)
                                 .endsWith("0")
                         ? ""
@@ -59,7 +61,7 @@ class _ExpensePageState extends State<ExpensePage> {
                                 .toStringAsFixed(2)
                                 .endsWith(".00") &&
                             curr
-                                .calcComparableCostDaily()
+                                .calcComparableAmountDaily()
                                 .toStringAsFixed(3)
                                 .endsWith("0")
                         ? ""
@@ -133,7 +135,7 @@ class _ExpensePageState extends State<ExpensePage> {
                                       style: TextStyle(fontSize: 20.0),
                                     ),
                                     Text(
-                                      "${curr.cost.toStringAsFixed(2)} ${curr.frequency.title}",
+                                      "${curr.amount.toStringAsFixed(2)} ${curr.frequency.title}",
                                       style: TextStyle(fontSize: 12.0),
                                     ),
                                   ],
@@ -155,12 +157,12 @@ class _ExpensePageState extends State<ExpensePage> {
                                   children: [
                                     //if (curr.frequency != Frequency.daily)
                                     Text(
-                                      "$estimateSymbolDaily${curr.calcComparableCostDaily().toStringAsFixed(2)} ${Frequency.daily.title}",
+                                      "$estimateSymbolDaily${curr.calcComparableAmountDaily().toStringAsFixed(2)} ${Frequency.daily.title}",
                                       style: TextStyle(fontSize: 12.0),
                                     ),
                                     //if (curr.frequency != Frequency.yearly)
                                     Text(
-                                      "$estimateSymbolYearly${curr.calcComparableCost().toStringAsFixed(2)} ${Frequency.yearly.title}",
+                                      "$estimateSymbolYearly${curr.calcComparableAmountYearly().toStringAsFixed(2)} ${Frequency.yearly.title}",
                                       style: TextStyle(fontSize: 12.0),
                                     ),
                                   ],
@@ -196,7 +198,7 @@ class _ExpenseInputDialogState extends State<ExpenseInputDialog> {
 
   int? _id;
   String _name = "";
-  double _cost = 0;
+  double _amount = 0;
   Frequency _freq = Frequency.monthly;
   String _desc = "";
 
@@ -205,7 +207,7 @@ class _ExpenseInputDialogState extends State<ExpenseInputDialog> {
     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;
     }
@@ -277,29 +279,29 @@ class _ExpenseInputDialogState extends State<ExpenseInputDialog> {
                         keyboardType:
                             TextInputType.numberWithOptions(decimal: true),
                         decoration: InputDecoration(
-                          labelText: "Cost",
+                          labelText: "${Expense.amountText}",
                           hintText: "Example: 10.00",
                           hintStyle: TextStyle(fontSize: 10.0),
                           errorStyle: TextStyle(fontSize: 10.0),
                         ),
-                        initialValue: _cost != 0 ? _cost.toString() : "",
+                        initialValue: _amount != 0 ? _amount.toString() : "",
                         validator: (value) {
                           if (value == null || value.isEmpty) {
-                            return "Cost must be provided.";
+                            return "${Expense.amountText} must be provided.";
                           }
                           if (double.parse(value) < 0) {
                             return "Please use the Income page rather than having negative expenses.";
                           }
                           if (double.parse(value) < 0.01) {
-                            return "Cost must be one hundreth (0.01) or higher.";
+                            return "${Expense.amountText} must be one hundreth (0.01) or higher.";
                           }
                           if (double.tryParse(value) == null) {
-                            return "Cost must be a valid number.";
+                            return "${Expense.amountText} must be a valid number.";
                           }
                           return null;
                         },
                         onSaved: (value) {
-                          _cost = double.parse(value!);
+                          _amount = double.parse(value!);
                         },
                       ),
                       DropdownButtonFormField(
@@ -374,7 +376,7 @@ class _ExpenseInputDialogState extends State<ExpenseInputDialog> {
                       Expense expense = Expense(
                         id: _id,
                         name: _name,
-                        cost: _cost,
+                        amount: _amount,
                         frequency: _freq,
                         description: _desc,
                       );