如何使用asp.net 3层体系结构在数据库中插入空日期值

如何解决如何使用asp.net 3层体系结构在数据库中插入空日期值

if (objChildFees.childid != null)
{
        objChildFees.classstudentid = 0;
        objChildFees.classid = Convert.ToInt16(ddlClass.SelectedValue);
        objChildFees.centerid = Convert.ToInt32(Session[CommonVariables.gCentreId].ToString());
        objChildFees.roomno = 1;
        objChildFees.startdate = Convert.ToDateTime(txtStartDate.Text.ToString());
        objChildFees.enddate = Convert.ToDateTime(txtEndDate.Text.ToString());
        objChildFees.newfees = Convert.ToDecimal(txtfeesamt.Text.ToString());
        objChildFees.feestype = chkFeesPay.Checked == true ? 1 : 2;
        objChildFees.childdaystype = chkfulltime.Checked == true ? 1 : 2;
        objChildFees.feepermonthforsubsidized = 0;
        objChildFees.feepermonthforpartime = 0;
        objChildFees.feepermonthforparttimesubsidized = 0;
        objChildFees.activestatus = true;
        objChildFees.withdrawaldate = Convert.ToDateTime(txtwtdate.Text);
}

如何在此代码中添加空提款日期我遇到了错误：String was not recognized as a valid DateTime

解决方法

public static class Extenstions
{
    public string ToNullableString(this string value)
    {
         if (string.IsNullOrEmpty(value))
         {
             return null;
         }
         
         return value;
     }
}

确保withdrawaldate属性具有可空类型（DateTime?）

然后像这样Convert.ToDateTime(txtwtdate.Text.ToNullableString())

,

如果objChildFees.withdrawaldate为空，则可以将其设置为nullable DateTime。在尝试将其转换为txtwtdate.Text之前，请检查DateTime?的值

public class ChildFees 
{
  // The ? after DateTime indicates this variable should be a nullable datatype
  DateTime? withdrawldate {get; set;}
  ...
}

objChildFees.withdrawaldate = string.IsNullOrWhiteSpace(txtwtdate.Text) ? null : (DateTime?)Convert.ToDateTime(txtwtdate.Text);

在生产系统中，您可能希望使用DateTime.TryParse来确保txtwtdate.Text的值在转换时包含有效的日期字符串，以避免在转换过程中引发异常。