Andrey Khan's questions

我不止一次读到不建议使用 statefullWidget。BottomNavigationBar在中切换页面的示例body。没有statefullWidget这个例子怎么办？使用块？还是仅适用于业务逻辑？

class HomeScreenTest extends StatefulWidget {

@override
  _HomeScreenTestState createState() => _HomeScreenTestState();
}

class _HomeScreenTestState extends State<HomeScreenTest> {
  int _currentIndex = 0;
  final pages = [
    Page1(),
    Page2(),
    Page3(),
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: pages[_currentIndex],
      bottomNavigationBar: BottomNavigationBar(
        onTap: (index) {
          setState(() {
            _currentIndex = index;
          });
        },
        currentIndex: _currentIndex,
        items: [
          BottomNavigationBarItem(
            title: Text('pag1'),
          ),
          BottomNavigationBarItem(
            title: Text('page'),
          ),
          BottomNavigationBarItem(
            title: Text('page3'),
          ),
        ],
      ),
    );
  }
}

有一个发布请求示例：

POST /api HTTP/1.1
Host: checkout.test.paycom.com
X-Auth: 100fe486b33784292111b7dc
Cache-Control: no-cache

{
    "id": 123,
    "method": "cards.create",
    "params": {
        "card": { "number": "4444444444444444", "expire": "0420"},
        "amount": 350000,
        "save": true
    }
}

功能：

class Service {

 static String url = 'checkout.test.paycom.com';
  static Map<String, dynamic> headers = {
    'Host': 'checkout.test.paycom.com',
    'X-Auth': '3423343243434',
    'Cache-Control': 'no-cache'
  };

  Future createCard(
      String id, String cardNumber, String expire, int amount) async {
    try {
      Map<String, dynamic> body = {
        'id': id,
        'method': 'cards.create',
        'params': {
          'card': {
            'number': cardNumber,
            'expire': expire,
          },
          'amount': amount,
        },
      };
      final response = await http.post(url, body: body, headers: headers);
      if (response.statusCode == 200) {
        final result = jsonDecode(response.body);
        List<CardModel> data = result['params']['card'];

        print(data);
      }
    } catch (e) {
      print(e.toString());
    }
    return null;
  }
}


 factory CardModel.fromJson(Map<String, dynamic> json) {
return CardModel(
  id: json['id'],
  cardNumber: json['number'],
  expire: json['expire'],
  amount: int.parse(json['amount']),
);

}

给出错误类型“_InternalLinkedHashMap<String, Object>”不是类型转换中“String”类型的子类型。我究竟做错了什么？

产品已添加到工作表，但不保存产品。热重启或切换页面时，工作表为空。

class ProductUi extends StatelessWidget { 
 ProductTest productTest;
  ProductUi(this.productTest);

  @override
  Widget build(BuildContext context) {
    final  productBloc = BlocProvider.of<ProductBloc>(context);
    return Scaffold(
      body: Container(
          child: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(productTest.name),
            RaisedButton(
              onPressed: () {
                productBloc.add(AddToCart(productTest: productTest));
              },
              child: Text('add to cart'),
            ),
          ],
        ),
      )),
    );
  }
}

功能

 class CartService {
     List<ProductTest> cartProduct = [];
      Future addProduct(ProductTest productTest) async {
        return cartProduct.add(productTest);      
      }
    }

堵塞

class ProductBloc extends Bloc<ProductEvent, ProductState> {
      CartService cartService = CartService();
      ProductBloc({@required this.cartService});
      @override
      ProductState get initialState => ProductInitial();

      @override
      Stream<ProductState> mapEventToState(ProductEvent event) async* {
        if (event is AddToCart) {
          await cartService.addProduct(event.productTest);
        }
      }
    }

事件

class AddToCart extends ProductEvent {
      ProductTest productTest;   
      AddToCart({this.productTest});
      @override
      List<Object> get props => [];
    }

主屏幕

 class HomeScreenTest extends StatefulWidget {
      @override
      _HomeScreenTestState createState() => _HomeScreenTestState();
    }

class _HomeScreenTestState extends State<HomeScreenTest> {
  CartService cartService = CartService();

  @override
  Widget build(BuildContext context) {    
    return Scaffold(
      appBar: AppBar(
        title: Padding(
          padding: const EdgeInsets.only(top: 4),
          child: SizedBox(
            height: kToolbarHeight,
            child: Image.asset('assets/dafna_logo.png'),
          ),
        ),
        backgroundColor: Colors.blueGrey,
        elevation: 20,
      ),
      body: CategoryTest(),
    );
  }
}




  class CategoryTest extends StatefulWidget {
      @override
      _CategoryTestState createState() => _CategoryTestState();
    }

class _CategoryTestState extends State<CategoryTest> {
  CartService cartService = CartService();
  @override
  Widget build(BuildContext context) {
    BlocProvider.of<ProductBloc>(context)..add(LoadCategoriesEvent());
    return Scaffold(
      backgroundColor: Colors.blueGrey[400],
      body: SingleChildScrollView(
        child: Padding(
          padding: EdgeInsets.fromLTRB(20, 15, 20, 15),
          child: Column(
            children: <Widget>[
              Text('Категории'),
              BlocBuilder<ProductBloc, ProductState>(
                builder: (context, state) {
                  if (state is ProductLoaded) {
                    return categoryColumn(
                        state.categoriesTest, state.productTest);
                  } else {
                    return Container();
                  }
                },
              )
            ],
          ),
        ),
      ),
    );
  }

  Widget categoryColumn(
      List<CategoriesTest> categoriesTest, List<ProductTest> productTest) {
    return Column(
      children: categoriesTest.map((category) {
        return Card(
          color: Colors.blueGrey[300],
          elevation: 10.0,
          margin: EdgeInsets.fromLTRB(10, 10, 10, 10),
          child: InkWell(
            onTap: () {
              Navigator.push(
                  context,
                  MaterialPageRoute(
                      builder: (context) => BlocProvider(
                          create: (context) =>
                              ProductBloc(cartService: cartService),
                          child: ProductList(
                            categoriesTest: category,                               
                          ))));
            },
            child: Container(
              padding: EdgeInsets.all(20),
              child: Column(
                children: <Widget>[
                  Text(
                    category.categoryname,
                  ),
                ],
              ),
            ),
          ),
        );
      }).toList(),
    );
  }


class ProductList extends StatefulWidget {
  CategoriesTest categoriesTest;
  ProductList({@required this.categoriesTest});

  @override
  _ProductListState createState() => _ProductListState();
}

class _ProductListState extends State<ProductList> {
  CartService cartService = CartService();

  @override
  Widget build(BuildContext context) {
    BlocProvider.of<ProductBloc>(context)..add(LoadProductListEvent());
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.blueGrey,
      ),
      backgroundColor: Colors.blueGrey[100],
      body: SingleChildScrollView(
        child: Padding(
          padding: EdgeInsets.fromLTRB(20, 30, 20, 15),
          child: Column(
            children: <Widget>[
              BlocBuilder<ProductBloc, ProductState>(
                builder: (context, state) {
                  if (state is TableListLoaded) {
                    return tableListColumn(
                        state.productTest, widget.categoriesTest);
                  } else {
                    return Container();
                  }
                },
              )
            ],
          ),
        ),
      ),
    );
  }

  Widget tableListColumn(
      List<ProductTest> productTest, CategoriesTest categoriesTest) {
    return Column(
      children: productTest
          .where((product) => product.category == categoriesTest.categoryname)
          .map((product) {
        return Card(
          elevation: 10.0,

          child: InkWell(
            onTap: () {
              Navigator.push(
                  context,
                  MaterialPageRoute(
                      builder: (context) => BlocProvider(
                          create: (context) =>
                              ProductBloc(cartService: cartService),
                          child: ProductUi(product))));
            },
            child: Container(
              padding: EdgeInsets.all(15),
              child: Column(
                children: <Widget>[
                  Image.network(product.image),
                  Text(product.name),
                ],
              ),
            ),
          ),
        );
      }).toList(),
    );
  }
}

使用块的用户授权问题。

 Widget build(BuildContext context) {
    return MaterialApp(
     home: MultiBlocProvider(
    providers: [
      BlocProvider(
        create: (context) => AuthBloc(authServiceTest: authServiceTest)
          ..add(AppStartedEvent()),
      ),
    ],
    child: BlocBuilder<AuthBloc, AuthState>(builder: (context, state) {
        if (state is Authenticated) {
          return app(state.user);
        } else if (state is UnAuthenticated) {
          return HomeScreenTest();
        } else {
          return Container();
        }
      }),
    ),
  ),
);
  }

  Widget app(FirebaseUser user) {
    return Center(
      child: Text('hello'),
    );
  }
}

堵塞

class AuthBloc extends Bloc<AuthEvent, AuthState> {
 AuthServiceTest authServiceTest;
  AuthBloc({@required AuthServiceTest authServiceTest}) {
    this.authServiceTest = authServiceTest;
  }

  @override
  AuthState get initialState => AuthInitial();

  @override
  Stream<AuthState> mapEventToState(AuthEvent event) async* {
    if (event is AppStartedEvent) {
      try {
        var isSignedin = await  authServiceTest.isSignedIn();
        if (isSignedin) {
          var user = await  authServiceTest.currentUser();
          yield Authenticated(user: user);
        } else {
          yield UnAuthenticated();
        }
      } catch (e) {
        yield UnAuthenticated();
      }
    }
  }
}

阻止事件

class AppStartedEvent extends AuthEvent {
  @override
  List<Object> get props => throw UnimplementedError();
}

阻塞状态

class Authenticated extends AuthState {
  final FirebaseUser user;

  Authenticated({@required this.user});
  @override
  List<Object> get props => [];
}

class UnAuthenticated extends AuthState {
  @override
  List<Object> get props => throw UnimplementedError();

所有功能

class AuthServiceTest {

 FirebaseAuth auth = FirebaseAuth.instance;

  Future registerUser(String email, String password) async {
    var authResult = await auth.createUserWithEmailAndPassword(
        email: email, password: password);
    return authResult.user;
  }

  Future signIn(email, password) async {
    var authResult = await auth.signInWithEmailAndPassword(
      email: email,
      password: password,
    );
    return authResult.user;
  }

  Future signOut() async {
    await auth.signOut();
  }

  Future<bool> isSignedIn() async {
    var currentUser = await auth.currentUser();
    return currentUser != null;
  }

  Future currentUser() async {
    var user = await FirebaseAuth.instance.currentUser();
    return user;
  }
}

授权工作，在它应该显示应用程序小部件之后，但它没有。或者逻辑或功能块中的问题，我没有正确注册以获取用户。

页面来自Appbar

Widget build(BuildContext context) {
return Scaffold(
    appBar: AppBar(
      elevation: 0.0,
      title: Text('Admin panel'),
      leading: IconButton(
        icon: Icon(Icons.menu),
        onPressed: menuButtonPressed, <<<<<<?
      ),
    ),
    body: BlocProvider<NavigationBloc>(
      create: (context) => NavigationBloc(),
      child: Stack(
        children: <Widget>[
          BlocBuilder<NavigationBloc, NavigationStates>(
            builder: (context, navigationState) {
              return navigationState as Widget;
            },
          ),
          TestMenu(),

测试菜单页面

 class _TestMenu extends State<TestMenu> with SingleTickerProviderStateMixin {
  AnimationController _animation;

  @override
  void initState() {
    _animation = AnimationController(
      value: 1,
      vsync: this,
      duration: drawerAnimationDuration,
    );

    super.initState();
  }

  @override
  void dispose() {
    _animation.dispose();
    super.dispose();
  }

  void menuButtonPressed() {
    if (_animation.isAnimating) return;
    _animation.isCompleted ? _animation.reverse() : _animation.forward();
  }

  @override
  Widget build(BuildContext context) {
    return SlideTransition(
      position: Tween<Offset>(
        begin: Offset(-1, 0),
        end: Offset.zero,
      ).animate(_animation),
      child: Row(
        children: <Widget>[
          Container(
            width: drawerWidth,
            decoration: BoxDecoration(
              border: Border(right: BorderSide(color: Colors.grey[300])),
            ),

menuButtonPressed隐藏和显示侧边菜单。是否可以从页面 c 调用此函数AppBar。

products 集合有一个布尔值，在创建产品时自动设置为 true。如何改变它使用Switch？

return StreamBuilder<List<Product>>(
    stream: ProductService().products,
    builder: (context, snapshot) {
      if (snapshot.hasData) {
        return DataTable(
          columns: [
            ),
            DataColumn(
              label: Text('isActive'),
            ),
          ],
          rows: snapshot.data.map((products) {
            return DataRow(cells: [
              DataCell(
                Switch(
                    value: products.isActive,
                    onChanged: (bool notActive) {
                      setState(() {
                        products.isActive = notActive;
                        print(products.isActive);
                        updateStatus(bool notActive);

                      });
                    }),
              ),
            ]);
          }).toList(),
        );
      }
      return Container();
    });

试图这样做

 void updateStatus(bool notActive) {
_firestore.document().updateData({'isActive': notActive});

}

Firestore 有一个我在 中显示的集合DataTable。还有一个 onTap 函数，我试图通过它显示我的产品数据。数据应显示在 中showDialog()。

return StreamBuilder<List<Product>>(
    stream: ProductService().products,
    builder: (context, snapshot) {
      if (snapshot.hasData) {
        return DataTable(
          columns: [
            DataColumn(
              label: Text('Наименование'),
            ),
          ],
          rows: snapshot.data.map((products) {
            return DataRow(cells: [
              DataCell(
                Text(products.name),
                onTap: () => showDialog(
                  context: context,
                  builder: (context) => ProductDetails(),

                )
              ),
              DataCell(Text(products.date)),
              DataCell(Text(products.category)),
            ]);
          }).toList(),
        );

showDialog 返回一个 ProductDetails 小部件。

Widget build(BuildContext context) {
return StreamBuilder<Product>(
    stream: ProductService().productDetails,
    builder: (context, snapshot) {
      if (snapshot.hasData) {
        Product productDetails = snapshot.data;
        return Dialog(
          child: Container(
            width: 500,
            height: 500,
            child: Form(
              key: _formProductDetails,
              child: Column(
                children: <Widget>[
                  TextFormField(
                      initialValue: productDetails.name,
                    ),
                ],
              ),
            ),
          ),
        );
          else {
        return Text('error');
      }

产品类别

    class ProductService {
  var dbTimeKey = DateTime.now();
  var formatDate = DateFormat('dd-MM-yyyy HH:mm:ss');


  final CollectionReference _firestore =
      Firestore.instance.collection("products");

  Future addProduct(_nameproductController, _priceproductController,
      _productQuantityController, _currentCategory, url, bool isActive) async {
    String date = formatDate.format(dbTimeKey);

    _firestore.document(date).setData({
      'name': _nameproductController,
      'price': _priceproductController,
      'category': _currentCategory,
      'image': url,
      'date': date,
      'quantity': _productQuantityController,
      'isActive': true,

    });
  }

  List<Product> _productList(QuerySnapshot snapshot) {
    return snapshot.documents.map((doc) {
      return Product(
        name: doc.data['name'] ?? '',
        price: doc.data['price'] ?? '0',
        category: doc.data['category'] ?? '',
        quantity: doc.data['quantity'] ?? '0',
        date: doc.data['date'] ?? '',
        image: doc.data['image'] ?? '',
        isActive: doc.data['isActive'] ?? '',
      );
    }).toList();
  }

  Stream<List<Product>> get products {
    return _firestore.snapshots().map(_productList);
  }

  Product productDetailsFromSnap(DocumentSnapshot snapshot) {
    return Product(
      name: snapshot.data['name'],
      price: snapshot.data['price'],
      category: snapshot.data['category'],
      quantity: snapshot.data['quantity'],
      date: snapshot.data['date'],
      image: snapshot.data['image'],
      isActive: snapshot.data['isActive'],
    );
  }

  Stream<Product> get productDetails {
    return _firestore.document().snapshots().map(productDetailsFromSnap);
  }
}

问题是当您单击产品名称时，它应该打开一个窗口并显示产品的详细信息，它会返回错误。productdetails 小部件不了解从哪个文档中提取信息。

无法将图像的 URL 保存在 Firestore 中，文档已创建，图像保存在 Storage 中，一切正常。可能是排序问题？

    class ProductService {
  Firestore _firestore = Firestore.instance;

  void createProduct(_nameproductController, _priceproductController,
      _currentCategory, url) async {

    _firestore.collection("products").document().setData({
      'name': _nameproductController,
      'price': _priceproductController,
      'category': _currentCategory,
      'image': url,
    });
  }
}

贮存

    void uploadImg() async {
var timekey = DateTime.now();
fb.StorageReference storageReference =
    fb.storage().ref('imgProduct/${timekey.toString()}.jpg');
fb.UploadTaskSnapshot uploadTask = await storageReference
    .put(_image1, fb.UploadMetadata(contentType: 'image/jpg'))
    .future;

var imageUrl = await uploadTask.ref.getDownloadURL();

url = imageUrl.toString();
print('Image Url' + url);}

提交按钮

RaisedButton(
   onPressed: () async {
     if (_formKeyProduct.currentState.validate()) {
        uploadImg();
        ProductService().addProduct(
         _nameproductController.text,
         _priceproductController.text,
         _currentCategory.categoryname.toString(),
         url,
        );

        _formKeyProduct.currentState.reset();
        _nameproductController.clear();
        _priceproductController.clear();
     }

     setState(() {
        _currentCategory = null;
     });
  },

我正在尝试在 WebApp 中创建管理面板。原生抽屉在打开时完全覆盖内容，我想让它在单击图标时始终打开和关闭。如何制作隐藏/显示功能？编码：

class AdminPage extends StatefulWidget {
  @override
  _AdminPage createState() => _AdminPage();
}

bool isColapsed = true;

class _AdminPage extends State<AdminPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        leading: Builder(
            builder: (context) => IconButton(
                icon: Icon(Icons.menu),
                onPressed: () => Scaffold.of(context).openEndDrawer())),
        backgroundColor: Colors.deepOrange,
        actions: <Widget>[IconButton(icon: Icon(Icons.menu), onPressed: () {})],
      ),
      body: Stack(
        children: <Widget>[
          Container(
            color: Colors.amberAccent,
            child: Center(
              child: Text('content'),
            ),
          ),
        ],
      ),
    );
  }
}

重新设计的小部件

    class SideMenu extends StatefulWidget {
  @override
  _SideMenuState createState() => _SideMenuState();
}

bool isSideBarOpened = true;
final _animationDuration = const Duration(milliseconds: 500);

class _SideMenuState extends State<SideMenu> {
  Widget widgetForBody = FirstPage();
  @override
  Widget build(BuildContext context) {
    final screenWidth = MediaQuery.of(context).size.width;
    return AnimatedPositioned(
      duration: _animationDuration,
      top: 0,
      bottom: 0,
      left: isSideBarOpened ? 0 : -300,
      right: isSideBarOpened ? 0 : screenWidth - 35,
      child: Row(
        children: <Widget>[
          Flexible(
            child: Container(
              width: 300.0,
              color: Colors.deepOrange,
              child: Column(
                children: <Widget>[
                  ListTile(
                    title: Text('First Page'),
                    onTap: () {
                      setState(() {
                        widgetForBody = FirstPage();
                      });
                    },
                  ),

                ],
              ),
            ),
          ),
          Align(
            alignment: Alignment(0, -0.9),
            child: Container(
              width: 35,
              height: 100,
              color: Colors.deepOrange,
              child: IconButton(
                icon: Icon(Icons.menu),
                onPressed: () {
                  setState(() {
                    isSideBarOpened = !isSideBarOpened;
                  });
                },
              ),
            ),
          ),
        ],
      ),
    );
  }
}

我是 Flutter 的新手，我决定创建一个应用商店。我有 10 个类别，我创建了一个自定义小部件，其中有一个点击功能。是否可以从一键式功能直接指向这 10 个类别？

class ListOfCategory extends StatefulWidget {
  @override
  _ListOfCategoryState createState() => _ListOfCategoryState();
}

class _ListOfCategoryState extends State<ListOfCategory> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: ListView(
        // padding: EdgeInsets.only(left: 40, right: 40),
        children: <Widget>[
          Padding(
            padding: EdgeInsets.only(top: 30, left: 40, right: 40),
            child: Image.asset('assets/dafna_logo.png'),
          ),
          SizedBox(height: 15),
          Padding(
            padding: const EdgeInsets.all(8.0),
            child: Wrap(
              children: <Widget>[
                _categoryTap('name'),
                _categoryTap('name'),
                _categoryTap('name'),
                _categoryTap('name'),
                _categoryTap('name'),
                _categoryTap('name'),
                _categoryTap('name'),
                _categoryTap('name'),
                _categoryTap('name'),
              ],
            ),
          ),
        ],
      ),
    );
  }
}

Widget _categoryTap(String _nameCategory) {
  return InkWell(
    onTap: () {},
    child: Padding(
      padding: EdgeInsets.all(5),
      child: Column(
        children: <Widget>[
          Container(
            height: 120,
            width: 120,
            color: Colors.blue,
          ),
          Container(
            width: 120,
            height: 35,
            // color: Colors.red,
            child: Text(
              _nameCategory,
            ),
          ),
        ],
      ),
    ),
  );
}