Question

我正在使用 WCF引用来调用Quote表中的最后一行。现在我在我的WCF应用程序中编写了这个方法以获取最后一行，但我不知道它是否有效（我正在尝试测试它）：

public void GetLastQuote()
{
    using (TruckDb db = new TruckDb())
    {
        var quote = (from qData in db.Quotes
                     where qData.Id == qData.RepresetativeId
                     orderby qData.Id descending
                     select qData).First();
    }
}

在我的WPF应用程序中，我正在使用WCF引用并调用GetLastQuoteAsync()方法，但它给出了以下错误：

无法将void分配给隐式类型的局部变量

以下是我在WPF应用程序中尝试调用GetLastQuoteAsync()引用的方法。

private async void wListOfBills_Loaded(object sender, RoutedEventArgs e)
{
    using (TruckServiceClient client = new TruckServiceClient())
    {
        var quote = await client.GetLastQuoteAsync(); // -> This is where the error lies.
        var bills = await client.GetListOfBillsAsync(quote.Item.Id);
        if (bills == null)
        {
            dgFloor.IsEnabled = true;
            return;
        }
        dgFloor.ItemsSource = bills.Select(x => new ListOfBillsView
        {
            Code = x.StockCode,
            Group = x.GroupName,
            Description = x.StockDescription,
            Qty = x.Quantity,
            Length = x.Length,
            Width = x.Width,
            Weight = x.Weight,
            Price_m = x.PricePerMeter,
            Cost = x.Cost,
            Section = x.TruckSection.ToString()
        }).ToList();
    }
}

我看到有些人有同样的问题，但我不完全了解如何在我自己的问题中实施解决方案。如果有人可以提供帮助，我将不胜感激！：）

Answer 1

你想调用你的查询返回的内容，但是围绕该查询的方法没有返回任何内容，因为它的类型是无效的。

我假设您要返回public static void main(String[] args) { try { File firstFile = new File("/Users/TLQ/Desktop/report-12689-M2398-1.xlsx"); File secondFile = new File("/Users/TLQ/Desktop/report-12695-M2390-1.xlsx"); FileInputStream excellFile1 = new FileInputStream(firstFile); FileInputStream excellFile2 = new FileInputStream(secondFile); org.apache.poi.ss.usermodel.Workbook workbook1 = WorkbookFactory.create(excellFile1); org.apache.poi.ss.usermodel.Workbook workbook2 = WorkbookFactory.create(excellFile2); org.apache.poi.ss.usermodel.Sheet sheet1a = workbook1.getSheetAt(0); org.apache.poi.ss.usermodel.Sheet sheet2a = workbook2.getSheetAt(0); addSheet(sheet1a, sheet2a,secondFile.getAbsolutePath().substring(secondFile.getAbsolutePath().lastIndexOf("/")+1, secondFile.getAbsolutePath().indexOf("."))); excellFile1.close(); // save merged file File mergedFile = new File( "/Users/TLQ/Desktop/Albert_1.xlsx"); if (!mergedFile.exists()) { mergedFile.createNewFile(); } FileOutputStream out = new FileOutputStream(mergedFile); workbook1.write(out); out.close(); System.out.println(firstFile.getAbsolutePath().substring(firstFile.getAbsolutePath().lastIndexOf("/")+1, firstFile.getAbsolutePath().indexOf("."))); } catch (Exception e) { e.printStackTrace(); } } public static void addSheet(org.apache.poi.ss.usermodel.Sheet mergedSheet, org.apache.poi.ss.usermodel.Sheet sheet,String name) { // map for cell styles Map<Integer, org.apache.poi.ss.usermodel.CellStyle> styleMap = new HashMap<Integer, org.apache.poi.ss.usermodel.CellStyle>(); org.apache.poi.ss.usermodel.Row row2 = mergedSheet.createRow((short) 0); org.apache.poi.ss.usermodel.Cell mcell2 = row2.createCell((short) 0); mcell2.setCellValue("report-12689-M2398-1.xlsx"); // This parameter is for appending sheet rows to mergedSheet in the end org.apache.poi.ss.usermodel.Row row1 = sheet.createRow((short) 0); org.apache.poi.ss.usermodel.Cell mcell = row1.createCell((short) 0); mcell.setCellValue(name); org.apache.poi.ss.usermodel.Row row1Empty = sheet.createRow((short) 0); org.apache.poi.ss.usermodel.Cell mcellEmpty = row1.createCell((short) 0); int len = mergedSheet.getLastRowNum(); for (int j = sheet.getFirstRowNum(); j <= sheet.getLastRowNum(); j++) { org.apache.poi.ss.usermodel.Row row = sheet.getRow(j); org.apache.poi.ss.usermodel.Row mrow = mergedSheet.createRow(len + j + 1); try { for (int k = row.getFirstCellNum(); k < row.getLastCellNum(); k++) { org.apache.poi.ss.usermodel.Cell cell=null; if(row.getCell(k)!=null){ cell = row.getCell(k); }else{ cell= row.createCell(k); } mcell = mrow.createCell(k); if (cell.getSheet().getWorkbook() == mcell.getSheet() .getWorkbook()) { mcell.setCellStyle(cell.getCellStyle()); } else { int stHashCode = cell.getCellStyle().hashCode(); org.apache.poi.ss.usermodel.CellStyle newCellStyle = styleMap.get(stHashCode); if (newCellStyle == null) { newCellStyle = mcell.getSheet().getWorkbook() .createCellStyle(); newCellStyle.cloneStyleFrom(cell.getCellStyle()); styleMap.put(stHashCode, newCellStyle); } mcell.setCellStyle(newCellStyle); } switch (cell.getCellType()) { case HSSFCell.CELL_TYPE_FORMULA: mcell.setCellFormula(cell.getCellFormula()); break; case HSSFCell.CELL_TYPE_NUMERIC: mcell.setCellValue(cell.getNumericCellValue()); break; case HSSFCell.CELL_TYPE_STRING: mcell.setCellValue(cell.getStringCellValue()); break; case HSSFCell.CELL_TYPE_BLANK: mcell.setCellType(HSSFCell.CELL_TYPE_BLANK); break; case HSSFCell.CELL_TYPE_BOOLEAN: mcell.setCellValue(cell.getBooleanCellValue()); break; case HSSFCell.CELL_TYPE_ERROR: mcell.setCellErrorValue(cell.getErrorCellValue()); break; default: mcell.setCellValue(cell.getStringCellValue()); break; } } } catch (Exception e) { } } }类型的对象，因此您需要将方法更改为：

Quote

同样//change from void to Quote public Quote GetLastQuote() { using (TruckDb db = new TruckDb()) { var quote = (from qData in db.Quotes where qData.Id == qData.RepresetativeId orderby qData.Id descending select qData).First(); //new return quote; } }与GetLastQuote()不同您是否发布了错误的方法，会产生同样的错误？

如果还有此方法的异步版本，它应该看起来类似于：

GetLastQuoteAsync()

无法使用Entity Framework 6为隐式类型的局部变量分配void

1 个答案: