Question

我有一个对象列表，其中9个属性中有8个经常重复，最后一个属性在整个属性中不同。

使用C＃和LINQ对象我想检索前8个属性的（分组）不同列表，其中第9个属性在整个组中连接...

public class MyClass
{
    public int property1 {get;set;}
    public string property2 {get;set;}
    public string property3 {get;set;}
}

我可能有一个列表，如：

var list1 = new List<myClass>
        {
            new myClass {property1 = 1, property2 = "foo", property3 = "This"},
            new myClass {property1 = 1, property2 = "foo", property3 = "is"},
            new myClass {property1 = 1, property2 = "foo", property3 = "a"},
            new myClass {property1 = 1, property2 = "foo", property3 = "test"},
            new myClass {property1 = 1, property2 = "foo", property3 = "value"},
            new myClass {property1 = 2, property2 = "bar", property3 = "Here's"},
            new myClass {property1 = 2, property2 = "bar", property3 = "a"},
            new myClass {property1 = 2, property2 = "bar", property3 = "second"}
        };

我正在努力编写能够产生以下对象列表的最高效的LINQ表达式：

{
    {property1 = 1, property2 = "foo", newProperty3 = "This is a test value"},
    {property1 = 2, property2 = "bar", newProperty3 = "Here's a second"}
};

有人会介意帮忙吗？

Answer 1

您要查找的是带有复合键的GroupBy查询：

list1.GroupBy(x => new { x.property1, x.property2 })
     .Select(g => new 
                    { 
                      property1 = g.Key.property1, 
                      property2 = g.Key.property2, 
                      newProperty3 = string.Join(" ", g.Select(x => x.property3))
                    });

Linq to Objects：Distinct + Concatenation

1 个答案: