Linq和C＃中的克隆对象

Question

This question is not about cloning objects but about the correct use of Linq to use an extension method to clone a list of objects.Code if just for illustration.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    class Program
   {
        static void Main(string[] args)
        {
           List<MyObj> myObjs = DB.GetAllMyObjs(); //fictitious database calls returns a list of Objs


        //I now want to use my extension method clone to clone all the MyObjs in myObjs
        // this throws an error;
        List<MyObj> myObj2 = myObjs.ForEach(a => a.Clone()).ToList(); //ERROR = "."cannot be applied to type void


    }
}

public class MyObj 
{
    public int Id { get; set; }



}
public static class MyObjExtentions
{
    public static MyObj  Clone(this MyObj myObj)
    {
        var myObjClone = new MyObj();
        myObjClone.Id = myObj.Id;
        return myObjClone;
    }
}

}

I am getting an error on the Linq code. is it possible to do this or do you need a foreach loop.

Answer 1

Change ForEach To Select

List<MyObj> myObj2 = myObjs.Select(a => a.Clone()).ToList();

ForEach is part of the list implementation. not linq