c# - 获取两次之间的记录列表 C# Linq To Entities

Question

在我的应用程序中，我想用数据库中符合特定条件的记录填充一个列表:

public ActionResult SelectYearGraph(int year)
{
    var lstAllSummaries = db.Summaries.ToList();

    var lstMonths =
       lstAllSummaries.Where(x => x.FlightDay.Year == year)
           .Select(x => x.TestDay.Month)
           .Distinct()
           .OrderBy(x => x)
           .ToList();

    List<string> lstMonthNames = new List<string>();
    List<int> lstCountSummaries = new List<int>();
    List<int> lstCountDailySummariesDifferentTime = new List<int>();

    var tsSix = new TimeSpan(6, 0, 0);
    var tsTen = new TimeSpan(22, 0, 0);

    foreach (var item in lstMonths)
    {
        var monthName = CultureInfo.CurrentCulture.DateTimeFormat.GetMonthName(item);
        lstMonthNames.Add(monthName);
        foreach (var item in lstMonths)
        {
            var monthName = CultureInfo.CurrentCulture.DateTimeFormat.GetMonthName(item);
            lstMonthNames.Add(monthName);
            lstCountDailySummaries.Add(lstAllSummaries.Count(x => x.FlightDay.Month == item && x.FlightDay.Year == year 
            && (x.FlightDay.TimeOfDay >= tsSix && x.FlightDay.TimeOfDay <= tsTen)
            && !x.deleted));
            lstCountDailySummariesDifferentTime.Add(lstAllSummaries.Count(x => x.FlightDay.Month == item && x.FlightDay.Year == year
            && (x.FlightDay.TimeOfDay > tsTen || x.FlightDay.TimeOfDay < tsSix)
            && !x.deleted));
        }
    }
    ... // more down here but not relevant to question
}

当我运行它时，出现运行时错误:

The specified type member 'TimeOfDay' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported.

我试过了Date and Time Canonical Functions for LINQ-to-Entities ，但我收到了同样的错误。

如何获取早上 6 点到晚上 10 点之间的所有记录？

Answer 1

您不需要 TimeOfDay 只需读取 DateTime 的 Hour、Minute、Second 将为您提供相同的结果。

the TimeOfDay property returns a TimeSpan value that represents a DateTime value's time component.

所以只需将您的代码更改为:

...
&& (DbFunctions.CreateTime(x.TestDay.Hour, x.TestDay.Minute,x.TestDay.Second) > DbFunctions.CreateTime(6,0,0) 
&& (DbFunctions.CreateTime(x.TestDay.Hour, x.TestDay.Minute, x.TestDay.Second) < DbFunctions.CreateTime(22,0,0))
...

寻找跨越午夜的时间的问题在于，虽然时间可以是早上 6 点之后和晚上 10 点之前，但晚上 10 点之后和早上 6 点之前就不是这样了。

您需要将 AND 更改为 OR

...
&& (
  (DbFunctions.CreateTime(x.TestDay.Hour, x.TestDay.Minute,x.TestDay.Second) > DbFunctions.CreateTime(22,0,0) 
  || (DbFunctions.CreateTime(x.TestDay.Hour, x.TestDay.Minute, x.TestDay.Second) < DbFunctions.CreateTime(6,0,0))
)
...