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在我的LINQ查詢的賦值部分中，我需要檢查值是否爲空，如果是，則指定默認值。返回的值類型是十進制數，當我比較爲空時，我得到警告在LINQ查詢中檢查NULL的小數點
由於類型'decimal'的值永遠不等於'null'類型，因此表達式的結果始終爲'false' 「小數？
如果我嘗試比較，看是否值是0，那麼我的錯誤
演員陣容價值型「System.Decimal」失敗，因爲物化值爲null。結果類型的泛型參數或查詢都必須使用可爲空的類型。
什麼是檢查HoursWorked2是否爲空的最佳方法，併爲其分配默認值（如果它爲空）？
編輯： 我沒有想到會需要的一切所有的代碼，但因爲有些人認爲這是在這裏需要的是所有與它的代碼：
// AJAX: /TimeOverviewGrid
[Route("TimeOverviewGrid", Name = "Time Overview Grid")]
public ActionResult TimeOverviewGrid()
{
var PayPeriod = TimeCardHelper.GetCurrentPayPeriod();
var WeekBeforePayPeriod = PayPeriod.AddDays(-7);
try
{
var EmployeeID = EmployeeHelper.GetEmployeeID(User.Identity.Name);
using (var db = new JobSightDbContext())
{
var TimeOverviewData = (from th1 in db.TimeCardHeaders
join e in db.Employees on th1.EmployeeID equals e.ID
join so1 in db.StatusOptions on th1.CurrentStatusID equals so1.ID
join leftth2 in db.TimeCardHeaders.Where(timeCardHeader => timeCardHeader.WeekEndingDate == PayPeriod)
on th1.EmployeeID equals leftth2.EmployeeID into leftjointh2
from th2 in leftjointh2.DefaultIfEmpty()
join so2 in db.StatusOptions on th2.CurrentStatusID equals so2.ID into leftjoinso2
from th2Final in leftjoinso2.DefaultIfEmpty()
where th1.WeekEndingDate == WeekBeforePayPeriod && (e.ID == EmployeeID || e.ManagerID == EmployeeID)
orderby e.FirstName
select new DashboardTimeOverviewVM()
{
EmployeeID = e.ID,
Employee = string.Concat(e.FirstName, " ", e.LastName),
WeekOfDate1 = th1.WeekEndingDate,
HoursWorked1 = th1.TotalHoursWorked,
Status1 = so1.Name,
WeekOfDate2 = (th2.WeekEndingDate == null) ? PayPeriod : th2.WeekEndingDate,
HoursWorked2 = (th2.TotalHoursWorked == null) ? 0 : th2.TotalHoursWorked,
Status2 = (string.IsNullOrEmpty(th2Final.Name)) ? "New" : th2Final.Name,
PTO = e.PTORemaining
}).ToList();
return Json(TimeOverviewData, JsonRequestBehavior.AllowGet);
}
}
catch (Exception ex)
{
Response.StatusCode = (int)HttpStatusCode.BadRequest;
return Json(new { responseText = "Error getting data, please try again later" }, JsonRequestBehavior.AllowGet);
}
}
public static DateTime GetCurrentPayPeriod()
{
var KnownPayPeriodDate = DateTime.Parse("2007-11-10");
while (KnownPayPeriodDate.CompareTo(DateTime.Today) < 0)
{
KnownPayPeriodDate = KnownPayPeriodDate.AddDays(14);
}
return ((KnownPayPeriodDate - DateTime.Today).Days < 7) ? KnownPayPeriodDate : KnownPayPeriodDate.AddDays(-14);
}
public static int GetEmployeeID(string adUserName)
{
adUserName = adUserName.Remove(0, 9);
using (var db = new JobSightDbContext())
{
return db.Employees.Where(employee => employee.ADUserName == adUserName).Select(employee => employee.ID).First();
}
}
public class DashboardTimeOverviewVM
{
public int EmployeeID { get; set; }
public string Employee { get; set; }
public DateTime WeekOfDate1 { get; set; }
public decimal HoursWorked1 { get; set; }
public string Status1 { get; set; }
public DateTime WeekOfDate2 { get; set; }
public decimal HoursWorked2 { get; set; }
public string Status2 { get; set; }
public decimal PTO { get; set; }
}
public class TimeCardHeader
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ID { get; set; }
public int EmployeeID { get; set; }
public DateTime WeekEndingDate { get; set; }
public decimal TotalHoursWorked { get; set; }
public int CurrentStatusID { get; set; }
public decimal OtherPay { get; set; }
public int? ApprovedByID { get; set; }
public DateTime? DateSubmitted { get; set; }
public DateTime? DateApproved { get; set; }
[Column(TypeName = "varchar(MAX)")]
public string ManagerNotes { get; set; }
[ForeignKey("EmployeeID")]
public Employee Employee { get; set; }
[ForeignKey("ApprovedByID")]
public Employee ApprovedBy { get; set; }
[ForeignKey("CurrentStatusID")]
public StatusOption CurrentStatus { get; set; }
}
public class Employee
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ID { get; set; }
[Required]
public string FirstName { get; set; }
[Required]
public string LastName { get; set; }
[Required]
public string ADUserName { get; set; }
[Required]
public string Email { get; set; }
public int? ManagerID { get; set; }
[Required]
public string EmploymentType { get; set; }
[Required]
public string PhoneNumber { get; set; }
[Required]
public string OfficeLocation { get; set; }
public string MobilePhoneNumber { get; set; }
public decimal PTORemaining { get; set; }
public decimal PTOAccrualRate { get; set; }
public DateTime StartDate { get; set; }
public DateTime? EndDate { get; set; }
public int ADPFileNumber { get; set; }
public int AirCardLateCheckinCount { get; set; }
public int VehicleLateCheckinCount { get; set; }
public int WexCardDriverID { get; set; }
public int? UpdatedByEmployeeID { get; set; }
public DateTime? DateUpdated { get; set; }
[ForeignKey("ManagerID")]
public Employee Manager { get; set; }
[ForeignKey("UpdatedByEmployeeID")]
public Employee UpdatedBy { get; set; }
}
public class StatusOption
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ID { get; set; }
[Required]
public string Name { get; set; }
}
一開始，'（th2.TotalHoursWorked = = 0）？ 0：th2.TotalHoursWorked'只是'th2.TotalHoursWorked'。現在，如果這是你想檢查無效的那個 - 你有沒有確定它在你的班級中被聲明爲「decimal？」？您沒有向我們展示'th2.TotalHoursWorked'或'DashboardTimeOverviewVM.HoursWorked2'的類型。如果你提供[mcve]，那真的會有所幫助，所以我們可以忽略不相關的部分並查看相關部分。 –