我有一个项目列表,其中一些项目可能具有特定项目属性的null /零值。我正在按其他财产分组项目。然后我想要的是选择我的属性!= null /零的那些组的First()元素,以及该属性等于null / 0的组中的所有项。怎么做?
答案 0 :(得分:0)
由于您的问题中没有相关数据和代码,请让我通过示例给出一般答案:
首先,让我们有一个示例类:
class Test
{
public int? First { get; set; }
public int? Second { get; set; }
public int? Third { get; set; }
}
...然后让我们填写它:
List<Test> list = new List<Test>
{
new Test {First = null, Second = 1, Third = 2},
new Test {First = 5, Second = 3, Third = 4},
new Test {First = 6, Second = null, Third = 8},
new Test {First = null, Second = 2, Third = 5},
new Test {First = 8, Second = null, Third = 14},
new Test {First = 21, Second = 2, Third = null},
new Test {First = 5, Second = 4, Third = 2},
new Test {First = 9, Second = 0, Third = 8}
};
...现在你可以这样做(如果我理解你的问题):
var result = list
.GroupBy(x => x.First) //grouping by First property
.Select(y => new
{
FirstNonNull = y.FirstOrDefault(z => z.Second != null), // first null in group by Second property
AllNull = y.Where(f => f.Second == null) // all null in group by Second property
}
);