Question

我有以下列表定义：

class ListItem
{
    public int accountNumber { get; set; }
    public Guid locationGuid { get; set; }
    public DateTime createdon { get; set; }
}
class Program
{
    static void Main(string[] args)
    {
        List<ListItem> entitiesList = new List<ListItem>();
        // Some code to fill the entitiesList
    }
}

entitiesList的accountNumbers中有重复项。我想找到重复的accountNumbers，在locationGuids上执行一个操作，其创建日期不是重复项的最新创建日期。如何操作列表以仅获取重复项accountNumber，最近创建的locationGuid和（较旧的）locationGuids？

Answer 1

List<ListItem> entitiesList = new List<ListItem>();
//some code to fill the list
var duplicates = entitiesList.OrderByDescending(e => e.createdon)
                    .GroupBy(e => e.accountNumber)
                    .Where(e => e.Count() > 1)
                    .Select(g => new
                    {
                        MostRecent = g.FirstOrDefault(),
                        Others = g.Skip(1).ToList()
                    });

foreach (var item in duplicates)
{
    ListItem mostRecent = item.MostRecent;
    List<ListItem> others = item.Others;
    //do stuff with others
}

Answer 2

duplicates = entitiesList.GroupBy(e => e.accountNumber)
                         .Where(g => g.Count() > 1)
                         .Select(g => g.OrderByDescending(x => x.createdon));

Answer 3

    List<ListItem> entitiesList = new List<ListItem>();
    var filtered = entitiesList.GroupBy(x => x.accountNumber).Where(g => g.Count() > 1).ToList().OrderByDescending(x => x.createdon);

从C＃List <object> </object>获取重复项

3 个答案: