Cast class into another class or convert class to another

Question

My question is shown in this code

I have class like that

public class MainCS
{
  public int A;
  public int B;
  public int C;
  public int D; 
}

public class Sub1
{
  public int A;
  public int B;
  public int C;
}


public void MethodA(Sub1 model)
{
  MainCS mdata = new MainCS() { A = model.A, B = model.B, C = model.C };   

  // is there a way to directly cast class Sub1 into MainCS like that    
  mdata = (MainCS) model;    
}

Solution 1

What he wants to say is:

"If you have two classes which share most of the same properties you can cast an object from class a to class b and automatically make the system understand the assignment via the shared property names?"

Option 1: Use reflection

Disadvantage : It's gonna slow you down more than you think.

Option 2: Make one class derive from another, the first one with common properties and other an extension of that.

Disadvantage: Coupled! if your're doing that for two layers in your application then the two layers will be coupled!

Let there be:

class customer
{
    public string firstname { get; set; }
    public string lastname { get; set; }
    public int age { get; set; }
}
class employee
{
    public string firstname { get; set; }
    public int age { get; set; } 
}

Now here is an extension for Object type:

public static T Cast<T>(this Object myobj)
{
    Type objectType = myobj.GetType();
    Type target = typeof(T);
    var x = Activator.CreateInstance(target, false);
    var z = from source in objectType.GetMembers().ToList()
        where source.MemberType == MemberTypes.Property select source ;
    var d = from source in target.GetMembers().ToList()
        where source.MemberType == MemberTypes.Property select source;
    List<MemberInfo> members = d.Where(memberInfo => d.Select(c => c.Name)
       .ToList().Contains(memberInfo.Name)).ToList();
    PropertyInfo propertyInfo;
    object value;
    foreach (var memberInfo in members)
    {
        propertyInfo = typeof(T).GetProperty(memberInfo.Name);
        value = myobj.GetType().GetProperty(memberInfo.Name).GetValue(myobj,null);

        propertyInfo.SetValue(x,value,null);
    }   
    return (T)x;
}  

Now you use it like this:

static void Main(string[] args)
{
    var cus = new customer();
    cus.firstname = "John";
    cus.age = 3;
    employee emp =  cus.Cast<employee>();
}

Method cast checks common properties between two objects and does the assignment automatically.

Solution 2

Use JSON serialization and deserialization:

using Newtonsoft.Json;

Class1 obj1 = new Class1();
Class2 obj2 = JsonConvert.DeserializeObject<Class2>(JsonConvert.SerializeObject(obj1));

---

Or:

public class Class1
{
    public static explicit operator Class2(Class1 obj)
    {
        return JsonConvert.DeserializeObject<Class2>(JsonConvert.SerializeObject(obj));
    }
}

Which then allows you to do something like

Class1 obj1 = new Class1();
Class2 obj2 = (Class2)obj1;

Solution 3

You have already defined the conversion, you just need to take it one step further if you would like to be able to cast. For example:

public class sub1
{
    public int a;
    public int b;
    public int c;

    public static explicit operator maincs(sub1 obj)
    {
        maincs output = new maincs() { a = obj.a, b = obj.b, c = obj.c };
        return output;
    }
}

Which then allows you to do something like

static void Main()
{
    sub1 mySub = new sub1();
    maincs myMain = (maincs)mySub;
}

Solution 4

You could change your class structure to:

public class maincs : sub1
{
   public int d; 
}

public class sub1
{
   public int a;
   public int b;
   public int c;
}

Then you could keep a list of sub1 and cast some of them to mainc.

Solution 5

By using following code you can copy any class object to another class object for same name and same type of properties.

public class CopyClass
{
    /// <summary>
    /// Copy an object to destination object, only matching fields will be copied
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="sourceObject">An object with matching fields of the destination object</param>
    /// <param name="destObject">Destination object, must already be created</param>
    public static void CopyObject<T>(object sourceObject, ref T destObject)
    {
        //  If either the source, or destination is null, return
        if (sourceObject == null || destObject == null)
            return;

        //  Get the type of each object
        Type sourceType = sourceObject.GetType();
        Type targetType = destObject.GetType();

        //  Loop through the source properties
        foreach (PropertyInfo p in sourceType.GetProperties())
        {
            //  Get the matching property in the destination object
            PropertyInfo targetObj = targetType.GetProperty(p.Name);
            //  If there is none, skip
            if (targetObj == null)
                continue;

            //  Set the value in the destination
            targetObj.SetValue(destObject, p.GetValue(sourceObject, null), null);
        }
    }
}

Call Method Like,

ClassA objA = new ClassA();
ClassB objB = new ClassB();

CopyClass.CopyObject(objOfferMast, ref objB);

It will copy objA into objB.

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