在C＃中将基类转换为派生类？

Question

I am trying to convert Base class to derived class object. See below code, I am having the issue when I converting. It is basic thing, but struggling.

[HttpGet]
[Route("/Edit/{Id}")]
public ActionResult Edit(int Id)
{

    List<ClassA> Data = Ctx.GetClassAFromId(Id);

    // Now Here I want convert ABC List<ClassA> to XyZ List<ClassA>
    //How to do that?
    return View(DataXYZ);
}

Model generate by EF

namespace ABC
{

    public partial class ClassA
    {
           public string First_name { get; set; }
           public string Last_Name { get; set; }
    }
}

Project model

namespace XYZ
{
    [MetadataType(typeof(ClassAMetadata))]
    public partial class ClassA:ABC.ClassA
    {

    }   

    public class ClassAMetadata
    {
        [DisplayName(@"First Name")]
        [Required]
        public string First_name { get; set; }


        [DisplayName(@"Last Name")] 
        [Required]       
        public string Last_Name { get; set; }
    }
}

How Can convert ABC.ClassA to XYZ.ClassA?

Edit:

we are working on i18n project. So we need to display each text in different languages. But our EF project is in different Namespace and web project is in different Namespace. that is the reason I deriving from base class

Answer 1

Even though their names are alike, they are completely different classes. It'd be just the same as if you called them Foo and Bar

You'll need a method that converts these objects. It takes a Foo object as parameter, then returns an equivalent Bar object

public Bar Foo_To_Bar(Foo myFoo)
{
    return new Bar() { Prop1 = myFoo.Prop1, Prop2 = myFoo.Prop2 };
}

Something like that. You'll probably also need a method that goes the other way around if you want to convert in both directions.

Note: If the classes have properties with the same name, I suggest you look into Automapper . It automates much of the boring work for you.

Edit
Apparently, your Foo inherits from Bar . That complicates things a bit more. I'll rework this answer when I get the time.

I don't see a use case for having your ViewModel (XYZ.ClassA) derive from your base entity (ABC.ClassA). Can you explain why this is needed? I think you're misusing inheritance here.

Generally speaking, you'd want your XYZ.ClassA to have a property of type ABC.ClassA (or any IEnumerable<ABC.ClassA> variation), not inherit from it.

Can you please confirm if this is an actual requirement, or can be part of the issue and is allowed to change if it fixes your problem?

Answer 2

You can't convert List<BaseClass> to List<DerivedClass>

What you can do is used linq:

listABC.Cast<XYZ.ClassA>.ToList()

But lookout - it is O(n) procedure

Answer 3

EDIT - based on the fact that one object is inherited from the other, see C#/.NET Little Wonders: Use Cast() and OfType() to Change Sequence Type

---

Couple of options:

1.

namespace ABC
{

    public partial class ClassA
    {
           public ClassA(XYZ.ClassA classToConvert)
           {
             this.First_name = classToConvert.First_name,
             this.Last_Name = classToConvert.Last_Name
           }

           public string First_name { get; set; }
           public string Last_Name { get; set; }
    }
}

Use it singularly:

 var newClassA = new ABC.ClassA((XYZ.ClassA)classA)

Do it in a list:

 List<ABC.ClassA> newClassAList = classAList.Select(p => new ABC.ClassA((XYZ.ClassA)p).ToList();

Or do it in a list without the above constructor and using an object initaliser

 List<ABC.ClassA> newClassAList = classAList.Select(p => new ABC.ClassA{First_name = p.First_name, Last_Name = p.Last_Name}.ToList();

1. As others have mentioned Use AutoMapper.

   • Use Nuget and add AutoMapper to your project (and some initalisation code)

   • Create your Map:

      Mapper.CreateMap<XYZ.ClassA, ABC.ClassA>(); 

   • Map your objects:

      var myABCClassA= Mapper.Map<XYZ.ClassA, ABC.ClassA>(myXYZClassA); 

   • As long as your property names on both classes match thats all the code you need

Answer 4

I created this today

public static void Map<T1, T2>(this T1 obj1, T2 obj2) where T1 : class where T2 : class
{
    IEnumerable<(PropertyInfo p1, PropertyInfo p2)> properties = typeof(T1).GetProperties()
        .Join(typeof(T2).GetProperties(), o => o.Name, t => t.Name, (o, t) => (o, t));
    foreach((PropertyInfo p1, PropertyInfo p2) in properties)
    {
        if (p1.CanWrite && p1.PropertyType == p2.PropertyType)
        {
            p1.SetValue(obj1, p2.GetValue(obj2));
        }
    }
}