c# 在 LINQ 查询返回的列表中查找项目并将其值与列表中的另一个项目进行比较

Question

我有一个在某一天 (d) 从 LINQ 查询返回的事件列表。

var findJSE = from a in db.DailyGPSTables 
    where (a.EventType == "JE" || a.EventType == "JS") && 
    a.EventDateTime.Value.Day == d.Day select a;

我想比较每组匹配的 JS 和 JE 的时间，看看它们的顺序是否正确，例如。 JS（工作开始）在 JE（工作结束）之前。如果只有一个JS和一个JE，我可以通过使用这个来完成。

foreach (DailyGPSTable e in itCompareDay)
{
  if (e.EventType == "JE" && e.EventDateTime.Value.Day == d.Day)
   {
     var findJS = from a in db.DailyGPSTables where a.EventType == "JS" && a.EventDateTime.Value.Day == d.Day select a;
     var time = findJS.FirstOrDefault();
     js = time.EventDateTime.Value;
      if (js > e.EventDateTime.Value)
       {
         EOOmessage = " On " + e.EventDateTime.Value.ToShortDateString() + " JE before JS";
         errorList.Add(EOOmessage);
         errorListRow.Add(dc);
       }
   }
}

但是，如果一天中有多个 JS 是允许的，我会遇到一些麻烦。 @NetMage 为我提供了一个极好的潜在修复，但没有时间尝试正确实施它。我最近的尝试在这里：

//Response.Write("<br>3rd Condition number of JE and JS on " + e.EventDateTime.Value.Day + " match now we see if there is more than one js");
if (findJS.Count() > 1)
{
    //Response.Write("<br>3.1 Condition there is more than one JS on " + e.EventDateTime.Value.Day + " get time of first js tag find the time of the first je tag");
    var jsTime = findJS.ToList();
    var jeTime = findJE.ToList();

    for (int j = 0; j <= jsTime.Count - 1; j++)
    {
        //Response.Write("<br><br>The " + j + " " + jsTime[j].EventType + " Starts on " + jsTime[j].EventDateTime + "<br>");
        var jsTimefor = jsTime[j].EventDateTime;
        for (int k = 0; k <= jeTime.Count - 1; k++)
        {
            //Response.Write("<br><br>The " + k + " " + jeTime[k].EventType + " Starts on " + jeTime[k].EventDateTime + "<br>");
            var jeTimefor = jeTime[k].EventDateTime;
            if (jeTime[k].EventDateTime < jsTime[j].EventDateTime)
            {
                //Response.Write(" The " + k + " " + jeTime[k].EventType + " Starts on " + jeTime[k].EventDateTime + " and < " + jsTime[j].EventDateTime + " which is " + jsTime[j].EventType + "<br>");
                EOOmessage = " On " + e.EventDateTime.Value.ToShortDateString() + " JE before JS";
                errorList.Add(EOOmessage);
                errorListRow.Add(dc);
            }
        }
    }
}

此尝试突出显示当天的所有 JE 行，并在没有的情况下创建错误条件。

更新：

我已经能够创建一个包含事件类型和时间的列表。

我将如何遍历该列表并确保第一个事件是 JS 并且它是最早的，下一个事件是 JE 并且按时间顺序是下一个。如果不报错。

我正在努力巩固和循环几天。这个21号只报一个错误，但是23号和27号都有错误。

for (DateTime d = startDate.Date; d <= endDate.Date; d = d.AddDays(1))
{
    Response.Write("<br>" + d + "<br>");
    var itCompareDay = (from h in db.DailyGPSTables
                        where h.EmplID == EmpID
                                && (h.EventDateTime.Value.Day == d.Day)
                                && (h.EventType == "SS" || h.EventType == "JS" || h.EventType == "LS" || h.EventType == "LE" || h.EventType == "JE" || h.EventType == "SE")
                        orderby h.EventDateTime
                        select h).ToList();
    string EOOmessage="";
    var lastEventType = itCompareDay.Any(x => x.EventType == "JS")? "JE" : "JS";
    foreach (DailyGPSTable e in itCompareDay)
    {
        Response.Write("<br>Event Type " + e.EventType + " Count " + dc + " for the " + d.Day + "<br>");
        if (e.EventDateTime.Value.Day == d.Day)
        {
            if (e.EventType == lastEventType)
            {
                var error = e.EventType == "JS"
                ? "JS before JE"
                : "JE before JS";
                Response.Write("<br>OUT OF SEQUENCE JE" + " ON " + e.EventDateTime.Value.ToShortDateString());
            }
            lastEventType = e.EventType;
        }
        dc = dc + 1;
    }
    rowNumber = rowNumber + dc;
}

Errors incorrectly reported.

Answer 1

我不确定我是否完全理解这里的设计，在我看来，最好将事件存储在 Event 表中，其中每一行都有一个 Start 和 End 列。

但是，如您所述，验证相关项目列表的一种方法是按EventDateTime 对列表进行排序，然后跟踪lastEventType。这样你可以检查当前事件类型是否等于lastEventType，那么它是一个错误。

例如：

public class Event
{
    public string EventType { get; set; }
    public DateTime? EventDateTime { get; set; }

    public override string ToString()
    {
        return $"{EventDateTime}: {EventType}";
    }
}

public class Program
{
    static void Main(string[] args)
    {            
        // Events for the day ordered by EventDateTime
        var events = new List<Event>
        {
            new Event {EventType = "JE",
                EventDateTime = DateTime.Parse("10/21/2018 12:23 PM")},
            new Event {EventType = "JE",
                EventDateTime = DateTime.Parse("10/21/2018 2:29 PM")},
            new Event {EventType = "JE",
                EventDateTime = DateTime.Parse("10/21/2018 2:40 PM")},
            new Event {EventType = "JS",
                EventDateTime = DateTime.Parse("10/21/2018 2:15 PM")},
            new Event {EventType = "JS",
                EventDateTime = DateTime.Parse("10/21/2018 3:12 AM")},
            new Event {EventType = "JS",
                EventDateTime = DateTime.Parse("10/21/2018 12:12 PM")},
        }.OrderBy(e => e.EventDateTime);

        // Initialize lastEventType to the opposite of the type of event we 
        // expect to see first (which is "JS" unless there are no "JS" events)
        var lastEventType = events.Any(e => e.EventType == "JS")
            ? "JE" : "JS";

        foreach (var e in events)
        {
            var errorMessage = string.Empty;

            // Check for error
            if (e.EventType == lastEventType)
            {
                Console.ForegroundColor = ConsoleColor.Red;

                // Create an error message
                var error = e.EventType == "JS"
                    ? "JS before JE"
                    : "JE before JS";

                var dateStr = e.EventDateTime?.ToShortDateString() ?? "[null date]";

                errorMessage = $" - On {dateStr} this error occurred: [{error}]";

                // Your code would include:
                // errorList.Add(errorMessage); 
                // errorListRow.Add(dc);
            }

            Console.WriteLine(e + errorMessage);
            Console.ResetColor();

            // Update the lastEventType with this event type
            lastEventType = e.EventType;
        }

        GetKeyFromUser("\nDone! Press any key to exit...");
    }
}

输出