Question

我有一个特定时间段的服务销售列表（activationDate到endDate）。我需要按月 - 年（例如2012年4月）生成销售报告。对于每个月，我想表明使用了多少月和多少天。

我的课程：

 public class SaleMonth
 {
    public DateTime MonthYear { get; set; }//.ToString("Y")

    public int FullMonth { get; set; }
    public int DaysMonth { get; set; }

   public string TotalMonths { get { return String.Format("{0:N2}", 
                                  (((FullMonth * 30.5) + DaysMonth) / 30.5)); } }
 }

我尝试过：

using (CompanyContext db = new CompanyContext())
{
   var saleList =  db.MySales.ToList();
   DateTime from = saleList.Min(s => s.ActivationDate), 
       to = saleList.Max(s => s.EndDate);

   for (DateTime currDate = from.AddDays(-from.Day + 1)
                                .AddTicks(-from.TimeOfDay.Ticks); 
                 currDate < to; 
                 currDate = currDate.AddMonths(1))
   {
      var sm = new SaleMonth
      {
          MonthYear = currDate,
          FullMonth = 0,
          DaysMonth = 0
      };

      var monthSell = saleList.Where(p => p.ActivationDate < currDate.AddMonths(1) 
                                              || p.EndDate > currDate);
      foreach (var sale in monthSell)
      {
         if (sale.ActivationDate.Month == sale.EndDate.Month
             && sale.ActivationDate.Year == sale.EndDate.Year)
         {//eg 4/6/13 - 17/6/13
             sm.DaysMonth += (sale.EndDate.Day - sale.ActivationDate.Day + 1);
         }
         else
         {
            if (sale.ActivationDate.Year == currDate.Year 
                  && sale.ActivationDate.Month == currDate.Month)
               sm.DaysMonth += (currDate.AddMonths(1) - sale.ActivationDate).Days;
            else if (sale.EndDate.Year == currDate.Year 
                  && sale.EndDate.Month == currDate.Month)
               sm.DaysMonth += sale.EndDate.Day;
            else if(sale.ActivationDate.Date <= currDate 
                  && sale.EndDate > currDate.AddMonths(1))
               sm.FullMonth++;
          }                               
       }
       vm.SaleMonthList.Add(sm);
   }
}

我有一种感觉，我在这里遗漏了一些东西，必须有一种更优雅的方式去做。

Here is a picture显示了一些销售情况以及从中生成的报告。

Answer 1

LINQ确实包含一种对数据进行分组的方法。首先看一下这个陈述：

// group by Year-Month
var rows = from s in saleList
    orderby s.MonthYear
    group s by new { Year = s.MonthYear.Year, Month = s.MonthYear.Month };

上述语句将获取您的数据并按年份对其进行分组，以便为每个年 - 月组合创建一个主键，并在该组中创建一组所有相应的SaleMonth项。

当您掌握了这一点时，下一步就是使用这些组来计算每组中想要计算的内容。因此，如果您只想查看每个年度月的所有FullMonths和DaysMonths，则可以执行以下操作：

var rowsTotals = from s in saleList
    orderby s.MonthYear
    group s by new { Year = s.MonthYear.Year, Month = s.MonthYear.Month } into grp
    select new
    {
        YearMonth = grp.Key.Year + " " + grp.Key.Month,
        FullMonthTotal = grp.Sum (x => x.FullMonth),
        DaysMonthTotal = grp.Sum (x => x.DaysMonth)
    };

修改

再看一下你在做什么之后，我认为这样做更有效率：

// populate our class with the time period we are interested in var startDate = saleList.Min (x => x.ActivationDate); var endDate = saleList.Max (x => x.EndDate); List<SaleMonth> salesReport = new List<SaleMonth>(); for(var i = new DateTime(startDate.Year, startDate.Month, 1); i <= new DateTime(endDate.Year, endDate.Month, 1); i = i.AddMonths(1)) { salesReport.Add(new SaleMonth { MonthYear = i }); } // loop through each Month-Year foreach(var sr in salesReport) { // get all the sales that happen in this month var lastDayThisMonth = sr.MonthYear.AddMonths(1).AddDays(-1); var sales = from s in saleList where lastDayThisMonth >= s.ActivationDate, where sr.MonthYear <= s.EndDate select s; // calculate the number of days the sale spans for just this month var nextMonth = sr.MonthYear.AddMonths(1); var firstOfNextMonth = sr.MonthYear.AddMonths(1).AddDays(-1).Day; sr.DaysMonth = sales.Sum (x => (x.EndDate < nextMonth ? x.EndDate.Day : firstOfNextMonth) - (sr.MonthYear > x.ActivationDate ? sr.MonthYear.Day : x.ActivationDate.Day)); // how many sales occur over the entire month sr.FullMonth = sales.Where (x => x.ActivationDate <= sr.MonthYear && nextMonth < x.EndDate).Count (); }

Answer 2

我同意雷姆先生的说法，LINQ是要走的路。由于你的计算很复杂，我也会创建一个辅助函数：

Func<DateTime, DateTime, bool> matchMonth = (date1, date2) => 
   date1.Month == date2.Month && date1.Year == date2.Year;

然后，您可以创建一个在计算中使用的函数：

Func<MySale, DateTime, int> calcDaysMonth = (sale, currDate) => 
{
     if (matchMonth(sale.ActivationDate, sale.EndDate))
     {
             return (sale.EndDate.Day - sale.ActivationDate.Day + 1);
     }
     else
     {
        if (matchMonth(sale.ActivationDate, currDate))
           return (currDate.AddMonths(1) - sale.ActivationDate).Days;
        else if (matchMonth(sale.EndDate, currDate)
           return sale.EndDate.Day;
        else 
           return 0;
     }
}

如果您将这些技术与Rem先生结合使用，您应该拥有一个漂亮，可读，简洁的功能，可以为您收集数据，并且易于测试和调试。

操作列表中的数据，按日期/月分组日期

2 个答案: