Question

我设计的NotificationViewModel以下：

public class NotificationViewModel
{
    public string NotificationText { get; set; }
    public DateTime Moment { get; set; }
    public string Icon { get; set; }
}

我正在生成我的通知数据，如下所示：

List<NotificationViewModel> model = new List<NotificationViewModel>();
int days = DateTime.Now.DayOfWeek - DayOfWeek.Sunday;
DateTime weekStart = DateTime.Now.AddDays(-days);
DateTime weekEnd = weekStart.AddDays(6);

var purchases = await context.tbl1.Where(x => x.created_date <= weekEnd && x.created_date >= weekStart)
                .Select(x => new NotificationViewModel()
                {
                      Icon = "fa fa-gbp",
                      Moment = x.created_date,
                      NotificationText = "A new purchase.",
                }).ToListAsync();
model.AddRange(purchases);

var stocks = await context.tbl2.Where(x => x.created_date <= weekEnd && x.created_date >= weekStart)
               .Select(x => new NotificationViewModel()
               {
                      Icon = "fa fa-cubes",
                      Moment = x.created_date,
                      NotificationText = "A new stock",
               }).ToListAsync();
model.AddRange(stocks);
var sales = await context.tbl3.Where(x => x.created_date <= weekEnd && x.created_date >= weekStart)
               .Select(x => new NotificationViewModel()
               {
                      Icon = "fa fa-shopping-cart",
                      Moment = x.created_date,
                      NotificationText = "A new sale",
                }).ToListAsync();
model.AddRange(sales);

model.OrderByDescending(x => x.Moment); 

//The above line does not order items according to their occurrence

我也尝试过如下：

model.OrderByDescending(c=> c.Moment.Date)
.ThenBy(c=> c.Moment.TimeOfDay);

但即使这样也行不通，模型保持不变。我将如何使用这些数据进行排序？任何见解都非常感谢..

Answer 1

因为方法OrderByDescending返回一个新序列，而不是就地排序序列。所以你需要：

model = model.OrderByDescending(x => x.Moment).ToList();

或者，您可以使用以下方式对列表进行排序：

model.Sort((x, y) => y.Moment.CompareTo(y.Moment));

值得注意的是，基于文档，OrderBy和OrderByDescending是稳定的排序方法（如果两个项具有相同的排序顺序，则保留序列中的原始顺序），而{{{ 1}}方法被记录为不稳定的Sort。

OrderbyDescending on date不按预期排序

1 个答案: