无法将我的数据上传到 firebase

Question

我对颤振很陌生，并试图学习它。我一直在尝试使用 firebase 并尝试将数据上传到它以用于存储目的。我一直在测试模式下使用实时数据库只是为了学习它，但不幸的是，由于某些问题，它现在对我不起作用。 我写的代码是： - 这是用于与我的 firebase 交互的提供程序文件

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;

import './product.dart';

class Products with ChangeNotifier {
  List<Product> _items = [
    Product(
      id: 'p1',
      title: 'Red Shirt',
      description: 'A red shirt - it is pretty red!',
      price: 29.99,
      imageUrl:
          'https://cdn.pixabay.com/photo/2016/10/02/22/17/red-t-shirt-1710578_1280.jpg',
    ),
    Product(
      id: 'p2',
      title: 'Trousers',
      description: 'A nice pair of trousers.',
      price: 59.99,
      imageUrl:
          'https://upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Trousers%2C_dress_%28AM_1960.022-8%29.jpg/512px-Trousers%2C_dress_%28AM_1960.022-8%29.jpg',
    ),
    Product(
      id: 'p3',
      title: 'Yellow Scarf',
      description: 'Warm and cozy - exactly what you need for the winter.',
      price: 19.99,
      imageUrl:
          'https://live.staticflickr.com/4043/4438260868_cc79b3369d_z.jpg',
    ),
    Product(
      id: 'p4',
      title: 'A Pan',
      description: 'Prepare any meal you want.',
      price: 49.99,
      imageUrl:
          'https://upload.wikimedia.org/wikipedia/commons/thumb/1/14/Cast-Iron-Pan.jpg/1024px-Cast-Iron-Pan.jpg',
    ),
  ];
  // var _showFavoritesOnly = false;

  List<Product> get items {
    // if (_showFavoritesOnly) {
    //   return _items.where((prodItem) => prodItem.isFavorite).toList();
    // }
    return [..._items];
  }

  List<Product> get favoriteItems {
    return _items.where((prodItem) => prodItem.isFavorite).toList();
  }

  Product findById(String id) {
    return _items.firstWhere((prod) => prod.id == id);
  }

  // void showFavoritesOnly() {
  //   _showFavoritesOnly = true;
  //   notifyListeners();
  // }

  // void showAll() {
  //   _showFavoritesOnly = false;
  //   notifyListeners();
  // }

  Future<void> addProduct(Product product) {
    const url = 'https://random-app-effc2-default-rtdb.firebaseio.com/products.json';
    return http
        .post(
      url,
      body: json.encode({
        'title': product.title,
        'description': product.description,
        'imageUrl': product.imageUrl,
        'price': product.price,
        'isFavorite': product.isFavorite,
      }),
    )
        .then((response) {
      final newProduct = Product(
        title: product.title,
        description: product.description,
        price: product.price,
        imageUrl: product.imageUrl,
        id: json.decode(response.body)['name'],
      );
      _items.add(newProduct);
      // _items.insert(0, newProduct); // at the start of the list
      notifyListeners();
    });
  }

  void updateProduct(String id, Product newProduct) {
    final prodIndex = _items.indexWhere((prod) => prod.id == id);
    if (prodIndex >= 0) {
      _items[prodIndex] = newProduct;
      notifyListeners();
    } else {
      print('...');
    }
  }

  void deleteProduct(String id) {
    _items.removeWhere((prod) => prod.id == id);
    notifyListeners();
  }
}

这是我的小部件代码，它直接与我的 firebase 交互：-

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

import '../providers/product.dart';
import '../providers/products.dart';

class EditProductScreen extends StatefulWidget {
  static const routeName = '/edit-product';

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

class _EditProductScreenState extends State<EditProductScreen> {
  final _priceFocusNode = FocusNode();
  final _descriptionFocusNode = FocusNode();
  final _imageUrlController = TextEditingController();
  final _imageUrlFocusNode = FocusNode();
  final _form = GlobalKey<FormState>();
  var _editedProduct = Product(
    id: null,
    title: '',
    price: 0,
    description: '',
    imageUrl: '',
  );
  var _initValues = {
    'title': '',
    'description': '',
    'price': '',
    'imageUrl': '',
  };
  var _isInit = true;
  var _isLoading = false;

  @override
  void initState() {
    _imageUrlFocusNode.addListener(_updateImageUrl);
    super.initState();
  }

  @override
  void didChangeDependencies() {
    if (_isInit) {
      final productId = ModalRoute.of(context).settings.arguments as String;
      if (productId != null) {
        _editedProduct =
            Provider.of<Products>(context, listen: false).findById(productId);
        _initValues = {
          'title': _editedProduct.title,
          'description': _editedProduct.description,
          'price': _editedProduct.price.toString(),
          // 'imageUrl': _editedProduct.imageUrl,
          'imageUrl': '',
        };
        _imageUrlController.text = _editedProduct.imageUrl;
      }
    }
    _isInit = false;
    super.didChangeDependencies();
  }

  @override
  void dispose() {
    _imageUrlFocusNode.removeListener(_updateImageUrl);
    _priceFocusNode.dispose();
    _descriptionFocusNode.dispose();
    _imageUrlController.dispose();
    _imageUrlFocusNode.dispose();
    super.dispose();
  }

  void _updateImageUrl() {
    if (!_imageUrlFocusNode.hasFocus) {
      if ((!_imageUrlController.text.startsWith('http') &&
              !_imageUrlController.text.startsWith('https')) ||
          (!_imageUrlController.text.endsWith('.png') &&
              !_imageUrlController.text.endsWith('.jpg') &&
              !_imageUrlController.text.endsWith('.jpeg'))) {
        return;
      }
      setState(() {});
    }
  }

  void _saveForm() {
    final isValid = _form.currentState.validate();
    if (!isValid) {
      return;
    }
    _form.currentState.save();
    setState(() {
      _isLoading = true;
    });
    if (_editedProduct.id != null) {
      Provider.of<Products>(context, listen: false)
          .updateProduct(_editedProduct.id, _editedProduct);
      setState(() {
        _isLoading = false;
      });
      Navigator.of(context).pop();
    } else {
      Provider.of<Products>(context, listen: false)
          .addProduct(_editedProduct)
          .then((_) {
        setState(() {
          _isLoading = false;
        });
        Navigator.of(context).pop();
      });
    }
    // Navigator.of(context).pop();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Edit Product'),
        actions: <Widget>[
          IconButton(
            icon: Icon(Icons.save),
            onPressed: _saveForm,
          ),
        ],
      ),
      body: _isLoading
          ? Center(
              child: CircularProgressIndicator(),
            )
          : Padding(
              padding: const EdgeInsets.all(16.0),
              child: Form(
                key: _form,
                child: ListView(
                  children: <Widget>[
                    TextFormField(
                      initialValue: _initValues['title'],
                      decoration: InputDecoration(labelText: 'Title'),
                      textInputAction: TextInputAction.next,
                      onFieldSubmitted: (_) {
                        FocusScope.of(context).requestFocus(_priceFocusNode);
                      },
                      validator: (value) {
                        if (value.isEmpty) {
                          return 'Please provide a value.';
                        }
                        return null;
                      },
                      onSaved: (value) {
                        _editedProduct = Product(
                            title: value,
                            price: _editedProduct.price,
                            description: _editedProduct.description,
                            imageUrl: _editedProduct.imageUrl,
                            id: _editedProduct.id,
                            isFavorite: _editedProduct.isFavorite);
                      },
                    ),
                    TextFormField(
                      initialValue: _initValues['price'],
                      decoration: InputDecoration(labelText: 'Price'),
                      textInputAction: TextInputAction.next,
                      keyboardType: TextInputType.number,
                      focusNode: _priceFocusNode,
                      onFieldSubmitted: (_) {
                        FocusScope.of(context)
                            .requestFocus(_descriptionFocusNode);
                      },
                      validator: (value) {
                        if (value.isEmpty) {
                          return 'Please enter a price.';
                        }
                        if (double.tryParse(value) == null) {
                          return 'Please enter a valid number.';
                        }
                        if (double.parse(value) <= 0) {
                          return 'Please enter a number greater than zero.';
                        }
                        return null;
                      },
                      onSaved: (value) {
                        _editedProduct = Product(
                            title: _editedProduct.title,
                            price: double.parse(value),
                            description: _editedProduct.description,
                            imageUrl: _editedProduct.imageUrl,
                            id: _editedProduct.id,
                            isFavorite: _editedProduct.isFavorite);
                      },
                    ),
                    TextFormField(
                      initialValue: _initValues['description'],
                      decoration: InputDecoration(labelText: 'Description'),
                      maxLines: 3,
                      keyboardType: TextInputType.multiline,
                      focusNode: _descriptionFocusNode,
                      validator: (value) {
                        if (value.isEmpty) {
                          return 'Please enter a description.';
                        }
                        if (value.length < 10) {
                          return 'Should be at least 10 characters long.';
                        }
                        return null;
                      },
                      onSaved: (value) {
                        _editedProduct = Product(
                          title: _editedProduct.title,
                          price: _editedProduct.price,
                          description: value,
                          imageUrl: _editedProduct.imageUrl,
                          id: _editedProduct.id,
                          isFavorite: _editedProduct.isFavorite,
                        );
                      },
                    ),
                    Row(
                      crossAxisAlignment: CrossAxisAlignment.end,
                      children: <Widget>[
                        Container(
                          width: 100,
                          height: 100,
                          margin: EdgeInsets.only(
                            top: 8,
                            right: 10,
                          ),
                          decoration: BoxDecoration(
                            border: Border.all(
                              width: 1,
                              color: Colors.grey,
                            ),
                          ),
                          child: _imageUrlController.text.isEmpty
                              ? Text('Enter a URL')
                              : FittedBox(
                                  child: Image.network(
                                    _imageUrlController.text,
                                    fit: BoxFit.cover,
                                  ),
                                ),
                        ),
                        Expanded(
                          child: TextFormField(
                            decoration: InputDecoration(labelText: 'Image URL'),
                            keyboardType: TextInputType.url,
                            textInputAction: TextInputAction.done,
                            controller: _imageUrlController,
                            focusNode: _imageUrlFocusNode,
                            onFieldSubmitted: (_) {
                              _saveForm();
                            },
                            validator: (value) {
                              if (value.isEmpty) {
                                return 'Please enter an image URL.';
                              }
                              if (!value.startsWith('http') &&
                                  !value.startsWith('https')) {
                                return 'Please enter a valid URL.';
                              }
                              if (!value.endsWith('.png') &&
                                  !value.endsWith('.jpg') &&
                                  !value.endsWith('.jpeg')) {
                                return 'Please enter a valid image URL.';
                              }
                              return null;
                            },
                            onSaved: (value) {
                              _editedProduct = Product(
                                title: _editedProduct.title,
                                price: _editedProduct.price,
                                description: _editedProduct.description,
                                imageUrl: value,
                                id: _editedProduct.id,
                                isFavorite: _editedProduct.isFavorite,
                              );
                            },
                          ),
                        ),
                      ],
                    ),
                  ],
                ),
              ),
            ),
    );
  }
}

Answer 1

final url = Uri.parse('https://random-app-effc2-default-rtdb.firebaseio.com/products.json');

使用此代码代替

const url = 'https://random-app-effc2-default-rtdb.firebaseio.com/products.json';