Question

假设我有一个定义为

的类

class Object
{
    public int ID { get;set; }
    public string Property { get; set; }

    public override bool Equals(object obj)
    {
        Object Item = obj as Object;
        return Item.ID == this.ID;
    }

    public override int GetHashCode()
    {
        int hash = 13;
        hash = (hash * 7) + ID.GetHashCode();
        return hash;       
    }
}

两个列表，定义如下：

List<Object> List1;
List<Object> List2;

这两个列表包含ID字段可能相同的对象，但Property字段可能有也可能没有。我希望得到List1中包含的所有对象的结果以及List2, with the condition that属性field must be set to中包含的所有对象“1”if it is set to“1”` 。结果必须包含不同的值（不同的ID）。

例如，如果我们有两个这样的列表：

List1 
-----  
ID = 0, Property = "1"
ID = 1, Property = ""
ID = 2, Property = "1"
ID = 3, Property = ""

List2
-----
ID = 1, Property = "1"
ID = 2, Property = ""
ID = 3, Property = ""

我需要一个看起来像这样的结果：

Result
-------
ID = 0, Property = "1"
ID = 1, Property = "1"
ID = 2, Property = "1"
ID = 3, Property = ""

目前它的工作原理如下：

var Result = List1.Except(List2).Concat(List2.Except(List1));
var Intersection = List1.Intersect(List2).ToList();
Intersection.ForEach(x => {
    x.Property = List1.Single(y => y.ID == x.ID).Property == "1" ? "1" : List2.Single(y => y.ID == x.ID).Property == "1" ? "1" : "";
});

Result = Result.Concat(Intersection);

......但ForEach非常慢。有人可以建议更快的方式吗？

Answer 1

var result = List1.Concat(List2)
                  .GroupBy(o => o.ID)
                  .Select(g => new Object() { 
                                   ID=g.Key,
                                   Property=g.Any(o=>o.Property=="1")?"1":""
                   })
                  .ToList();

Answer 2

var result = List1.Concat(List2)
        .OrderByDescending(o => o.Property)
        .GroupBy(g => o.ID)
        .Select(g => g.First())
        .ToList();

将两个实体列表与条件组合在一起

2 个答案: