使用 flutter 生成 pdf 并将其上传到 firebase 存储可以在 MacO 中工作，但不能与 WebApp 一起使用

Question

我正在为我工作的公司使用 Flutter 开发报价制作应用程序。该应用程序根据用户的选择生成 PDF 文档并将其存储在 Firebase 存储中。 PDF 生成和存储在 macOS 上运行得很好，但在 Flutter Web 上运行该应用程序时遇到了问题。

问题：

这个问题特别出现在 Flutter Web 上。尝试将生成的 PDF 文件存储在 Firebase 存储中时，应用程序会抛出错误：completer.complete。错误消息没有提供有关问题根本原因的太多信息，这使得我很难查明确切的问题。

代码：

我已经在 Firebase Storage 上分享了执行 PDF 生成和存储的代码 pdf_generator.dart

import 'package:flutter/services.dart';
import 'package:pdf/pdf.dart';
import 'package:path_provider/path_provider.dart';
import 'package:pdf/widgets.dart' as pw;
import 'package:shared_preferences/shared_preferences.dart';
import 'package:firebase_storage/firebase_storage.dart';
import 'package:firebase_core/firebase_core.dart';

import 'dart:io';

// Function to get the current quotation number
Future<int> _getQuotationNumber() async {
  SharedPreferences prefs = await SharedPreferences.getInstance();
  int quotationNumber = prefs.getInt('quotation_number') ?? 0;
  return quotationNumber;
}

// Function to increment the quotation number
Future<void> _incrementQuotationNumber() async {
  SharedPreferences prefs = await SharedPreferences.getInstance();
  int quotationNumber = await _getQuotationNumber();
  quotationNumber++;
  prefs.setInt('quotation_number', quotationNumber);
}

Future<String> generateQuotationPDF(
  Map<String, String> selectedItemNamesWithSKU,
  Map<String, int> quantities,
  Map<String, double> sellingPrices,
  Map<String, String> itemSku,
  Map<String, double> itemCostPrices,
  Map<String, double> itemPrices,
  double totalCost,
  double totalSellingPrice,
  double discount,
) async {
  // Initialize Firebase
  await Firebase.initializeApp();
  final pdf = pw.Document();

  // Create the PDF file name with the quotation number
  String directoryName = 'quotation_pdfs';

  final appDocumentsDir = await getApplicationDocumentsDirectory();
  String directoryPath = '${appDocumentsDir.path}/$directoryName';
  Directory(directoryPath).create(recursive: true);

  // Increment the quotation number
  await _incrementQuotationNumber();
  int quotationNumber = await _getQuotationNumber();

  String fileName =
      '$directoryName/PC-${quotationNumber.toString().padLeft(3, '0')}.pdf';

  final pdfPath = '${appDocumentsDir.path}/$fileName';

  // Load the logo image
  final logoImage = pw.MemoryImage(
    (await rootBundle.load('assets/cazalogo.webp')).buffer.asUint8List(),
  );
  // Get the current date
  final currentDate = DateTime.now();

  // Format the date to show only the date part (YYYY-MM-DD)
  final formattedDate =
      "${currentDate.year}-${currentDate.month.toString().padLeft(2, '0')}-${currentDate.day.toString().padLeft(2, '0')}";

  // Add content to the PDF document
  pdf.addPage(
    pw.Page(
      build: (pw.Context context) {
        final List<List<String?>> tableData = [
          ['Item', 'SKU', 'Qty', 'Cost', 'Selling Price'], // Header row
          for (String type in selectedItemNamesWithSKU.keys)
            if (selectedItemNamesWithSKU[type] != null &&
                quantities[selectedItemNamesWithSKU[type]] != 0)
              [
                selectedItemNamesWithSKU[type], // Item name with SKU
                itemSku[selectedItemNamesWithSKU[type]] ?? '', // SKU
                quantities[selectedItemNamesWithSKU[type]]?.toString() ?? '',
                '${(itemCostPrices[selectedItemNamesWithSKU[type]] ?? 0.0) * (quantities[selectedItemNamesWithSKU[type]] ?? 0)} BHD',
                '${(itemPrices[selectedItemNamesWithSKU[type]] ?? 0.0) * (quantities[selectedItemNamesWithSKU[type]] ?? 0)} BHD',
              ],
        ];

        return pw.Column(
          crossAxisAlignment: pw.CrossAxisAlignment.start,
          children: [
            // Display the logo/image
            pw.Center(
              child: pw.Image(logoImage, width: 50, height: 50),
            ),
            // Display the quotation number
            pw.Text('Quotation #PC-${quotationNumber}',
                style: const pw.TextStyle(fontSize: 20)),

            pw.Divider(),
            pw.SizedBox(height: 6),
            pw.Text('Cazasouq Trading W.L.L',
                style: const pw.TextStyle(fontSize: 10)),
            pw.Text('Cazasouq Shop 983d Block 332 Road 3221 Bu ashira',
                style: const pw.TextStyle(fontSize: 10)),
            // Display the date of creation
            pw.Text('$formattedDate',
                style: const pw.TextStyle(
                    fontSize: 10)), // Adjust font size if needed

            pw.SizedBox(height: 20),
            pw.Text('Quotation Details',
                style: const pw.TextStyle(fontSize: 15)),
            pw.Divider(),
            pw.SizedBox(height: 10),
            // Display the chosen items only in the table
            // ignore: deprecated_member_use
            pw.Table.fromTextArray(
              headerStyle:
                  pw.TextStyle(fontWeight: pw.FontWeight.bold, fontSize: 10),
              cellStyle: const pw.TextStyle(
                  fontSize: 7), // Smaller font size for items in the table
              border: pw.TableBorder.all(),
              headerDecoration:
                  const pw.BoxDecoration(color: PdfColors.grey300),
              cellHeight: 25,
              cellAlignments: {
                0: pw.Alignment.centerLeft,
                1: pw.Alignment.center,
                2: pw.Alignment.center,
                3: pw.Alignment.center,
                4: pw.Alignment.center,
              },
              headerHeight: 20,
              headerPadding: const pw.EdgeInsets.all(5),
              cellPadding: const pw.EdgeInsets.all(5),
              data: tableData,
              // Set the widths of each column here using the 'columnWidths' property
              columnWidths: {
                0: const pw.FlexColumnWidth(5), // Item column width
                1: const pw.FlexColumnWidth(2), // SKU column width
                2: const pw.FlexColumnWidth(1), // Quantity column width
                3: const pw.FlexColumnWidth(2), // Cost (BHD) column width
                4: const pw.FlexColumnWidth(
                    2), // Selling Price (BHD) column width
              },
            ),
            pw.SizedBox(height: 10),
            pw.Row(
              mainAxisAlignment: pw.MainAxisAlignment.spaceBetween,
              children: [
                pw.Text('Total Cost: $totalCost BHD',
                    style: const pw.TextStyle(fontSize: 9)),
                pw.Text('Total Selling Price: $totalSellingPrice BHD',
                    style: const pw.TextStyle(fontSize: 9)),
              ],
            ),
            pw.SizedBox(height: 5),
            pw.Row(
              mainAxisAlignment: pw.MainAxisAlignment.spaceBetween,
              children: [
                pw.Text('Discount: $discount BHD',
                    style: const pw.TextStyle(fontSize: 9)),
                pw.Text(
                    'Selling Price After Discount: ${totalSellingPrice - discount} BHD',
                    style: const pw.TextStyle(fontSize: 9)),
              ],
            ),
            pw.SizedBox(height: 5),
            pw.Row(
              mainAxisAlignment: pw.MainAxisAlignment.spaceBetween,
              children: [
                pw.Text('Margin: ${totalSellingPrice - totalCost} BHD',
                    style: const pw.TextStyle(fontSize: 9)),
                pw.Text(
                    'Margin After Discount: ${totalSellingPrice - totalCost - discount} BHD',
                    style: const pw.TextStyle(fontSize: 9)),
              ],
            ),
            pw.SizedBox(height: 5),
            pw.Text(
                'Selling Price After Discount + VAT: ${(totalSellingPrice - discount) * 1.1} BHD',
                style: const pw.TextStyle(fontSize: 9)),
          ],
        );
      },
    ),
  );

  // Save the PDF file to a file
  final file = File(pdfPath);
  await file.writeAsBytes(await pdf.save());

  // Store the PDF file in Firestore
  final firebaseStorage = FirebaseStorage.instance;
  final reference = firebaseStorage.ref().child(fileName);
  final uploadTask = reference.putFile(file);

  // Wait for the upload to complete
  final TaskSnapshot snapshot = await uploadTask;

  // Check if the upload was successful
  if (snapshot.state == TaskState.success) {
    // Get the download URL of the uploaded PDF file
    final downloadUrl = await snapshot.ref.getDownloadURL();

    // Optionally, show a message or perform other actions after the PDF is uploaded
    print('PDF quotation uploaded to: $downloadUrl');

    // Return the download link
    return downloadUrl;
  } else {
    throw FirebaseException(
        plugin: 'firebase_storage',
        code: 'object-not-found',
        message: 'No object exists at the desired reference.');
  }
}

pcbuilder.dart

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_typeahead/flutter_typeahead.dart';
import 'package:google_fonts/google_fonts.dart';
import '/functions/pdf_generator.dart';
import '/functions/product_data_loader.dart';
import '/functions/product_calculations.dart';
import 'package:firebase_core/firebase_core.dart';

import '/model/pcparts.dart';

class PCBuilderExcel extends StatefulWidget {
  @override
  _PCBuilderExcelState createState() => _PCBuilderExcelState();
}

enum PdfGenerationState {
  notStarted,
  loading,
  success,
  error,
}

void main() async {
  // Pass the Firebase web configuration options
  var firebaseOptions = const FirebaseOptions(
    apiKey: "",
    authDomain: "",
    projectId: "",
    storageBucket: "",
    messagingSenderId: "",
    appId: "",
    measurementId: "",
  );

  // Make sure to call WidgetsFlutterBinding.ensureInitialized() before Firebase.initializeApp()
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp(options: firebaseOptions);

  runApp(PCBuilderExcel());
}

class _PCBuilderExcelState extends State<PCBuilderExcel> {
  Map<String, double> itemPrices = {};
  Map<String, String> itemSku = {};
  Map<String, String> selectedItemNames = {};
  Map<String, int> quantities = {};
  Map<String, double> sellingPrices = {};
  double discount = 0.0;
  double totalCost = 0.0;
  double totalSellingPrice = 0.0;
  List<String> allItemNames = [];
  Map<String, double> itemCostPrices = {};

  // Define a Map to hold the TextEditingController for each item
  Map<String, TextEditingController> quantityControllers = {};
  bool showExtraCards = false; // Flag to show extra cards

  void initState() {
    super.initState();
    loadProductData(
      allItemNames,
      itemCostPrices,
      itemPrices,
      itemSku,
      selectedItemNames,
      quantities,
      _updateState,
    );

    // Initialize the quantityControllers with default values set to '1'
    for (var item in allItemNames) {
      quantityControllers[item] = TextEditingController(text: '1');
    }

    // Initialize the selectedItemNames map with the null value for all items
    selectedItemNames = {};
    for (var item in allItemNames) {
      selectedItemNames[item] = ''; // Use an empty string instead of null
    }
  }

  void _updateState() {
    setState(() {});
  }

  double calculateTotalCost() {
    return ProductCalculations.calculateTotalCost(
      selectedItemNames,
      itemCostPrices,
      quantities,
    );
  }

  double calculateTotalSellingPrice() {
    return ProductCalculations.calculateTotalSellingPrice(
      selectedItemNames,
      sellingPrices,
    );
  }

  double calculateMargin() {
    return ProductCalculations.calculateMargin(
      selectedItemNames,
      sellingPrices,
      itemCostPrices,
      quantities,
    );
  }

  double calculateSellingPriceAfterDiscount() {
    return ProductCalculations.calculateSellingPriceAfterDiscount(
      selectedItemNames,
      sellingPrices,
      discount,
    );
  }

  double calculateMarginAfterDiscount() {
    return ProductCalculations.calculateMarginAfterDiscount(
      selectedItemNames,
      sellingPrices,
      itemCostPrices,
      quantities,
      discount,
    );
  }

  void updateSellingPrice(String type) {
    ProductCalculations.updateSellingPrice(
      type,
      selectedItemNames,
      itemPrices,
      sellingPrices,
      itemCostPrices,
      quantities,
      () {
        setState(() {});
      },
    );
  }

  void _onGenerateQuotationButtonPressed() async {
    // Call the function to generate the PDF quotation
    await generateQuotationPDF(
      selectedItemNames, // Pass selectedItemNames as selectedItemNamesWithSKU
      quantities,
      sellingPrices,
      itemSku,
      itemCostPrices,
      itemPrices,
      calculateTotalCost(),
      calculateTotalSellingPrice(),
      discount,
    );
  }

  // Define the getIconForType method here
  IconData getIconForType(String type) {
    switch (type) {
      case 'CPU':
        return Icons.computer;
      case 'GPU':
        return Icons.videogame_asset;
      case 'RAM':
        return Icons.memory;
      case 'Storage':
        return Icons.storage;
      case 'Motherboard':
        return Icons.device_hub;
      default:
        return Icons.category;
    }
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'PC Builder Excel',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        // Use the NotoSans font as the default font
        fontFamily: GoogleFonts.notoSans().fontFamily,
      ),
      home: Scaffold(
        appBar: AppBar(
          title: const Text('PC Builder Excel'),
          centerTitle: true,
        ),
        body: Padding(
          padding: const EdgeInsets.all(16.0),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
                      const SizedBox(height: 10),
                      ElevatedButton(
                        onPressed: _onGenerateQuotationButtonPressed,
                        child: const Text('Generate Quotation'),
                      ),

Answer 1

您应该在应用程序中调用 Firebase.initializeApp 一次。

所以你必须只在主函数中调用Firebase.initializeApp。

Answer 2

当我将 storageBucket 行添加到 main 时，代码适用于我

  apiKey: "TEST",
  appId: "TEST",
  

存储桶：“测试”，

  messagingSenderId: "TEST",
  projectId: "TEST");