Question

我从excel表中提取数据并将其放入类属性中。在下面显示的代码段中，我尝试将数据添加到类型List<>的属性中。它执行时没有错误，但List<>计数始终为1。如下例所示，for循环运行5次，但在存在for循环后rah.rahTermDate计数为1。

for (int i = 0; i < 5; i++)
  {                  
    RawACAHireTermDates rahd = new RawACAHireTermDates();
    rahd.RawHireDate = Convert.ToDateTime(GetCellValue(GetCell(sheetData, Cells[i, k], j), workbookPart, false, true));
    rahd.RawTermDate = Convert.ToDateTime(GetCellValue(GetCell(sheetData, Cells[i, (k + 1)], j), workbookPart, false, true));
    rah.rahTermDate = new List<RawACAHireTermDates> { rahd };
    //  rah.rahTermDate.Add(rahd);               
  }

业务对象：

public class MasterClientGroupSheetData
    {
    public class RawACAHireTermDates
    {     
        public DateTime? RawHireDate { get; set; }
        public DateTime? RawTermDate { get; set; }                   
    }

    public class RawACAHireTermEmployee
    {
 ...........
        public List<RawACAHireTermDates> rahTermDate { get; set; }
    }
}

Answer 1

此代码在每次迭代时重新初始化List并丢失以前的数据。

public Response upload(@Multipart("id") int Id, @Multipart("file") Attachment attachment) {

您应该在rah.rahTermDate = new List<RawACAHireTermDates> { rahd };循环之外定义列表，然后使用for

向其添加项目

Answer 2

您正在循环中重新创建列表。在循环外创建一次：

{{1}}

Answer 3

每次迭代都会创建新列表 rah.rahTermDate = new List<RawACAHireTermDates> { rahd }; 它只包含一个项目，处理相同的迭代。要修复此问题，请在循环外定义列表，在循环中将元素添加到列表中，并在for循环后分配rah.rahTermDate。

Answer 4

这条线是罪魁祸首：

rah.rahTermDate = new List<RawACAHireTermDates> { rahd };

每次循环运行时，您都会将新列表设置为rah.rahTermDate。

您的代码应该更像这样：

//before the loop, declare a new List
rah.rahTermDate = new List<RawACAHireTermDates>();

for (int i = 0; i < 5; i++)
  {                  
    RawACAHireTermDates rahd = new RawACAHireTermDates();
    rahd.RawHireDate = Convert.ToDateTime(GetCellValue(GetCell(sheetData, Cells[i, k], j), workbookPart, false, true));
    rahd.RawTermDate = Convert.ToDateTime(GetCellValue(GetCell(sheetData, Cells[i, (k + 1)], j), workbookPart, false, true));

    //add to the existing list...
    rah.rahTermDate.Add(rahd);               
  }

将数据添加到List＆lt;＆gt;类型的属性中

4 个答案: