Question

使用C＃我想基于一个公共属性组合列表中的项目。例如：

class Merchant
{
    public string Name { get; set; }
    public string Value1 { get; set; }
    public string Value2 { get; set; }
    public DateTime? Value3 {get; set; }
}

列表包含：

{Name = "1", Value1 = "1", Value2 = "", Value3 = someDatetime}
{Name = "1", Value1 = "", Value2 = "2", Value3 = someDatetime}
{Name = "1", Value1 = "3", Value2 = "", Value3 = someDatetime}
{Name = "1", Value1 = "", Value2 = "4", Value3 = someDatetime}
{Name = "2", Value1 = "5", Value2 = "", Value3 = someOtherDatetime}

注意：空字符串值也可以为null

必需的输出列表：

{Name = "1", Value1 = "1,3", Value2 = "2,4", Value3 = someDateTime}
{Name = "2", Value1 = "5", Value2 = "", Value3 = someOtherDatetime}

这可以通过任何单个linq查询来实现吗？

更新：我添加了DateTime类型的新值。对于每个名称，只有一个日期时间（可以为null）。我如何在查询中包含它？

Answer 1

var query = list.GroupBy(m => m.Name)
    .Select(g => new Merchant
    {
        Name = g.Key,
        Value1 = String.Join(",", g
            .Where(m => !String.IsNullOrEmpty(m.Value1))
            .Select(m => m.Value1)),
        Value2 = String.Join(",", g
            .Where(m => !String.IsNullOrEmpty(m.Value2))
            .Select(m => m.Value2)),
        Value3 = g.First().Value3
    });

已更新 以考虑新的DateTime?列。

根据公共属性合并列表项

1 个答案: