Question

有人可以解释我如何使用b var a = Function.call.bind(b, null); function b(){ //do some stuff }来解决此问题：

GroupBy

这一个：Select其中：

public class BadClass{
    public int id; //can be grouped by id
    public string name; //identical for the same Id
    public bool flag; //identical for the same Id
    public int bId;
    public string bName;
    public int cId;
    public string cName;
}

我在BadClass中创建数据示例：

List <A>

我尝试做出类似的事情：

public class A {
    public int id;
    public string name;
    public bool flag;
    public List<B> bList;
}

public class B {
    public int id;
    public string name;
    public C c;
}

public class C {
    public int id;
    public int name;
}

但不知道如何做对。

更新

List<BadClass> badClass = new List<BadClass>() {
    new BadClass(){ id = 1, name = "A1", flag = true, bId = 1, bName = "B1", cId = 1, cName = "C1" },
    new BadClass(){ id = 1, name = "A1", flag = true, bId = 2, bName = "B2", cId = 3, cName = "C2" },
    new BadClass(){ id = 1, name = "A1", flag = true, bId = 3, bName = "B3", cId = 1, cName = "C1" },
    new BadClass(){ id = 2, name = "A2", flag = false, bId = 4, bName = "B4", cId = 2, cName = "C2" },
    new BadClass(){ id = 2, name = "A2", flag = false, bId = 5, bName = "B5", cId = 3, cName = "C3" }
};

/*
+----+------+-------+-----+-------+-----+-------+
| id | name |  flag | bId | bName | cId | cName |
+----+------+-------+-----+-------+-----+-------+
|  1 |  A1  |  true |  1  |   B1  |  1  |   C1  |
+----+------+-------+-----+-------+-----+-------+
|  1 |  A1  |  true |  2  |   B2  |  1  |   C1  |
+----+------+-------+-----+-------+-----+-------+
|  1 |  A1  |  true |  3  |   B3  |  3  |   C3  |
+----+------+-------+-----+-------+-----+-------+
|  2 |  A2  | false |  4  |   B4  |  2  |   C2  |
+----+------+-------+-----+-------+-----+-------+
|  2 |  A2  | false |  5  |   B5  |  3  |   C3  |
+----+------+-------+-----+-------+-----+-------+
*/

这是var result = badClass.GroupBy(x => x.id).Select(x => x. ???? ) ???? =(中的错误我需要将名称var result = badClass .GroupBy(x => x.id) .Select(x => new A { id = x.Key, name = x.First().name, flag = x.First().flag, bList = x.ToList() });更改为bList = x.ToList(); e.t.c。

解答：

bId

Answer 1

只需添加一个.Select和ToList，它将包含您需要的所有项目

var result = badClass.GroupBy(x => x.id).Select(x => x.ToList());

Answer 2

var result = badClass
        .GroupBy(x => x.id)
        .Select(x => new A
        {
            id = x.Key,
            name = x.First().name,
            flag = x.First().flag,
            bList = badClass.Where(y => y.id == x.Key).Select(y =>
                new B { id = y.bId, name = y.bName, c = new C { id = y.cId, name = y.cName } }).ToList()
        });

这可以让你得到你想要的东西

但说实话，我更倾向于使用foreach循环+ Dictionary来提高可读性。

.GroupBy（）之后得到List <someclass>

2 个答案: