投父对象到子对象在C＃ [英] cast the Parent object to Child object in C#

问题描述

您好我想投的父对象到子对象在C＃

Hi i want to cast the Parent object to Child object in C#

public class Parent
{
    public string FirstName {get; set;}
    public string LastName {get; set;}
    public string City {get; set;}
}

public class Child : Parent
{
    public string PhoneNumber {get; set;}
    public string MobileNumber {get; set;}
}

现在的情况是是父对象的名单，我想生成子对象的列表中，这样我可以有扩展的信息。

now the scenario is is a list of parent object and i want to generate list of child object so that i can have extended information

List<Parent> lstParent;
List<Child> lstChild = new List<Child>();

foreach(var obj in lstParent)
{
    lstChild.add((Child)obj);
}

作为子类继承父类，这样子类已经有父类的成员，我只是想自动填充他们，这样我可以填充数据成员子类

as child class inherited parent class so the child class already have the parent class member i just want to fill them automatically so that i can populate datamember of child class

推荐答案

如果我理解你的我只是想自动填补这些意见正确，你想创建一个与家长的值填充一个新的子对象，与新的属性的默认值。要做到这一点的最佳方式是创建一个构造函数，复制值：

If I understand your "I just want to fill them automatically" comment correctly, you want to create a new Child object that's populated with the values of the Parent, with default values for the new properties. Best way to do that is to create a constructor that copies the values:

public class Parent
{
   public string FirstName {get; set;}
    public string LastName {get; set;}
    public string City {get; set;}
}

public class Child : Parent
{
    public string PhoneNumber {get; set;}
    public string MobileNumber {get; set;}

    public Child (Parent parentToCopy)
    {
        this.FirstName = parentToCopy.FirstName;
        this.LastName = parentToCopy.LastName;
        this.City = parentToCopy.City;

        this.PhoneNumber = string.Empty; // Or any other default.
        this.MobileNumber = string.Empty;
    } 
}

现在你可以使用LINQ，像上述的答案，创建一个子从每个家长：

Now you can use LINQ, like the answers above, to create a Child out of each Parent:

List<Child> lstChild = lstParent.Select(parent => new Child(parent)).ToList();

请注意，这是非常相似的@ daryal的答案，但包装了家长对孩子的复制逻辑在构造函数中，而不是外面有它在新的儿童（）调用。

Note that this is very similar to @daryal's answer, but wraps the parent-to-child copying logic inside the constructor, rather than having it outside in the new Child() call.

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