feat(category): 添加分类功能并更新相关页面

- 新增 AddCategoryScreen 页面用于添加分类
- 更新 CategoryScreen 页面，添加浮动按钮用于导航到添加分类页面
- 修改 CategoryDropdown 组件，支持 ItemCategory 模型
- 更新 Item模型，将 location 改为字符串类型
- 修改 ItemScreen 页面，支持新的分类选择逻辑
- 更新数据库表结构，将 location 字段改为 TEXT 类型

lib/database/item_table.dart

@@ -3,7 +3,7 @@ CREATE TABLE items (
   id INTEGER PRIMARY KEY AUTOINCREMENT,
   name TEXT NOT NULL,
   category_id INTEGER,
-  location_id INTEGER,
+  location TEXT,
   description TEXT,
   price REAL,
   purchase_date TEXT,

lib/models/item_model.dart

@@ -7,7 +7,7 @@ class Item {
   // 分类
   final int? categoryId;
   // 位置
-  final int? locationId;
+  final String? location;
   // 描述
   final String? description;
   // 价格
@@ -27,7 +27,7 @@ class Item {
     this.id,
     required this.name,
     this.categoryId,
-    this.locationId,
+    this.location,
     this.description,
     this.price,
     this.purchaseDate,
@@ -41,7 +41,7 @@ class Item {
     return {
       'name': name,
       'category_id': categoryId,
-      'location_id': locationId,
+      'location': location,
       'description': description,
       'price': price,
       'purchase_date': purchaseDate,
@@ -57,7 +57,7 @@ class Item {
       id: map['id'],
       name: map['name'],
       categoryId: map['category_id'],
-      locationId: map['location_id'],
+      location: map['location'],
       description: map['description'],
       price: map['price'],
       purchaseDate: map['purchase_date'],

lib/screens/category_screens/add_category_screen.dart

@@ -0,0 +1,73 @@
+
+import 'package:flutter/material.dart';
+import 'package:item_tracker/provider/item_category_provider.dart';
+import 'package:item_tracker/screens/category_screens/category_screen.dart';
+import 'package:provider/provider.dart';
+
+import '../../models/item_category_model.dart';
+
+class AddCategoryScreen extends StatefulWidget {
+  @override
+  _AddCategoryScreenState createState() => _AddCategoryScreenState();
+}
+
+class _AddCategoryScreenState extends State<AddCategoryScreen> {
+  final _formKey = GlobalKey<FormState>();
+  final _nameController = TextEditingController();
+  final _descriptionController = TextEditingController();
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text('添加分类'),
+      ),
+      body: Column(
+        children: [
+          Form(
+            key: _formKey,
+            child: Column(
+              children: [
+                TextFormField(
+                  controller: _nameController,
+                  decoration: InputDecoration(labelText: '名称'),
+                  validator: (value) {
+                    if (value == null || value.isEmpty) {
+                      return '请输入名称';
+                    }
+                    return null;
+                  },
+                ),
+                TextFormField(
+                 controller: _descriptionController,
+                ),
+                ElevatedButton(
+                  onPressed: () {
+                    if (_formKey.currentState!.validate()) {
+                      final category = ItemCategory(
+                        name: _nameController.text,
+                        description: _descriptionController.text
+                      );
+
+                      Provider.of<ItemCategoryProvider>(context, listen: false).addCategory(category);
+
+                      // 弹窗提示添加成功
+                      ScaffoldMessenger.of(context).showSnackBar(SnackBar(
+                        content: Text('添加成功'),
+                        duration: Duration(seconds: 1),
+                      ));
+
+                      Navigator.pop(context);
+                      Navigator.pop(context);
+                    }
+                  },
+                  child: Text('添加'),
+                )
+              ]
+            )
+          )
+        ]
+      ),
+    );
+  }
+}

lib/screens/category_screens/category_screen.dart

@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
 
 import '../../provider/item_category_provider.dart';
+import 'add_category_screen.dart';
 import 'detail_category_screen.dart';
 
 class CategoryScreen extends StatefulWidget {
@@ -59,6 +60,18 @@ class _CategoryScreenState extends State<CategoryScreen> {
               }).toList(),
             ));
       }),
+        floatingActionButton:  FloatingActionButton(
+          onPressed: () async {
+            final shouldRefresh = await Navigator.push(
+              context,
+              MaterialPageRoute(builder: (context) => AddCategoryScreen()),
+            );
+          },
+          child: Icon(
+            Icons.add,
+            color: Colors.white,
+          )
+          )
     );
   }
 }

lib/screens/item_screens/item_screen.dart

@@ -1,4 +1,6 @@
 import 'package:flutter/material.dart';
+import 'package:item_tracker/models/item_category_model.dart';
+import 'package:item_tracker/provider/item_category_provider.dart';
 import 'package:item_tracker/screens/item_screens/widgets/category_dropdown.dart';
 import 'package:item_tracker/screens/item_screens/widgets/date_picker_field.dart';
 import 'package:item_tracker/screens/item_screens/widgets/description_field.dart';
@@ -56,12 +58,14 @@ class _FromTestRouteSate extends State<ItemScreen> {
   String _selected = '';
   double? _price;
   DateTime? _selectedDate;
-  String? _selectedCategory; // 当前选中的分类
+  int? _selectedCategory; // 当前选中的分类
   ItemIsUse? _itemIsUse = ItemIsUse.yes;
   GlobalKey<FormState> _formKey = GlobalKey<FormState>();
 
+  late ItemCategoryProvider _itemCategoryProvider;
+
   // 添加自定义分类列表
-  List<String> _categories = ['A', 'B', 'C', 'D']; // 自定义分类
+  late List<ItemCategory> _categories; // 自定义分类
 
   @override
   void initState() {
@@ -70,12 +74,22 @@ class _FromTestRouteSate extends State<ItemScreen> {
     if (item != null) {
       _name = item.name;
       _description = item.description!;
+      _location = (item.location == null ? '' : item.location)!;
       _selectedDate = item.purchaseDate;
     }
+    _itemCategoryProvider = Provider.of<ItemCategoryProvider>(context, listen: false);
+    Future.microtask(() {
+      _itemCategoryProvider =
+          Provider.of<ItemCategoryProvider>(context, listen: false);
+      _itemCategoryProvider.loadCategories();
+    });
   }
 
   @override
   Widget build(BuildContext context) {
+    final _c = _itemCategoryProvider.categories;
+    _categories = _c.toList();
+    print(_categories);
     return Scaffold(
       appBar: AppBar(
         title: Text('新增物品'),
@@ -130,7 +144,7 @@ class _FromTestRouteSate extends State<ItemScreen> {
                       final newItem = Item(
                         name: _name,
                         description: _description,
-                        purchaseDate: _selectedDate,
+                        categoryId: _selectedCategory,
                         isInUse: _itemIsUse,
                         price: _price,
                       );

lib/screens/item_screens/widgets/category_dropdown.dart

@@ -1,9 +1,10 @@
 import 'package:flutter/material.dart';
+import 'package:item_tracker/models/item_category_model.dart';
 
 class CategoryDropdown extends StatelessWidget {
-  final List<String> categories;
+  final List<ItemCategory> categories;
-  final String? selectedCategory;
+  final int? selectedCategory;
-  final ValueChanged<String?> onChanged;
+  final ValueChanged<int?> onChanged;
 
   CategoryDropdown({
     required this.categories,
@@ -13,12 +14,12 @@ class CategoryDropdown extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return DropdownButtonFormField<String>(
+    return DropdownButtonFormField<int>(
       value: selectedCategory,
       items: categories.map((category) {
-        return DropdownMenuItem<String>(
+        return DropdownMenuItem<int>(
-          value: category,
+          value: category.id,
-          child: Text(category),
+          child: Text(category.name),
         );
       }).toList(),
       onChanged: onChanged,