[c#] cast class into another class or convert class to another

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 is a way to directly cast class sub1 into main like that    
  mdata = (maincs) model;    
}

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.

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;
}

Using this code you can copy any class object to another class object for same name and same type of properties.

JavaScriptSerializer JsonConvert = new JavaScriptSerializer(); 
string serializeString = JsonConvert.Serialize(objectEntity);
objectViewModel objVM = JsonConvert.Deserialize<objectViewModel>(serializeString);

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.

I tried to use the Cast Extension (see https://stackoverflow.com/users/247402/stacker) in a situation where the Target Type contains a Property that is not present in the Source Type. It did not work, I'm not sure why. I refactored to the following extension that did work for my situation:

public static T Casting<T>(this Object source)
{
    Type sourceType = source.GetType();
    Type targetType = typeof(T);
    var target =  Activator.CreateInstance(targetType, false);
    var sourceMembers = sourceType.GetMembers()
        .Where(x => x.MemberType  == MemberTypes.Property)
        .ToList();
    var targetMembers = targetType.GetMembers()
        .Where(x => x.MemberType == MemberTypes.Property)
        .ToList();
    var members = targetMembers
        .Where(x => sourceMembers
            .Select(y => y.Name)
                .Contains(x.Name));
    PropertyInfo propertyInfo;
    object value;
    foreach (var memberInfo in members)
    {
        propertyInfo = typeof(T).GetProperty(memberInfo.Name);
        value = source.GetType().GetProperty(memberInfo.Name).GetValue(source, null);
        propertyInfo.SetValue(target, value, null);
    }
    return (T)target;
}

Note that I changed the name of the extension as the Name Cast conflicts with results from Linq. Hat tip https://stackoverflow.com/users/2093880/usefulbee

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;

var obj =  _account.Retrieve(Email, hash);

AccountInfoResponse accountInfoResponse = new AccountInfoResponse();

if (obj != null)
{               
   accountInfoResponse = 
   JsonConvert.
   DeserializeObject<AccountInfoResponse>
   (JsonConvert.SerializeObject(obj));
}

image description

There are some great answers here, I just wanted to add a little bit of type checking here as we cannot assume that if properties exist with the same name, that they are of the same type. Here is my offering, which extends on the previous, very excellent answer as I had a few little glitches with it.

In this version I have allowed for the consumer to specify fields to be excluded, and also by default to exclude any database / model specific related properties.

    public static T Transform<T>(this object myobj, string excludeFields = null)
    {
        // Compose a list of unwanted members
        if (string.IsNullOrWhiteSpace(excludeFields))
            excludeFields = string.Empty;
        excludeFields = !string.IsNullOrEmpty(excludeFields) ? excludeFields + "," : excludeFields;
        excludeFields += $"{nameof(DBTable.ID)},{nameof(DBTable.InstanceID)},{nameof(AuditableBase.CreatedBy)},{nameof(AuditableBase.CreatedByID)},{nameof(AuditableBase.CreatedOn)}";

        var objectType = myobj.GetType();
        var targetType = typeof(T);
        var targetInstance = Activator.CreateInstance(targetType, false);

        // Find common members by name
        var sourceMembers = from source in objectType.GetMembers().ToList()
                                  where source.MemberType == MemberTypes.Property
                                  select source;
        var targetMembers = from source in targetType.GetMembers().ToList()
                                  where source.MemberType == MemberTypes.Property
                                  select source;
        var commonMembers = targetMembers.Where(memberInfo => sourceMembers.Select(c => c.Name)
            .ToList().Contains(memberInfo.Name)).ToList();

        // Remove unwanted members
        commonMembers.RemoveWhere(x => x.Name.InList(excludeFields));

        foreach (var memberInfo in commonMembers)
        {
            if (!((PropertyInfo)memberInfo).CanWrite) continue;

            var targetProperty = typeof(T).GetProperty(memberInfo.Name);
            if (targetProperty == null) continue;

            var sourceProperty = myobj.GetType().GetProperty(memberInfo.Name);
            if (sourceProperty == null) continue;

            // Check source and target types are the same
            if (sourceProperty.PropertyType.Name != targetProperty.PropertyType.Name) continue;

            var value = myobj.GetType().GetProperty(memberInfo.Name)?.GetValue(myobj, null);
            if (value == null) continue;

            // Set the value
            targetProperty.SetValue(targetInstance, value, null);
        }
        return (T)targetInstance;
    }

You can provide an explicit overload for the cast operator:

public static explicit operator maincs(sub1 val)
{
    var ret = new maincs() { a = val.a, b = val.b, c = val.c };
    return ret;
}

Another option would be to use an interface that has the a, b, and c properties and implement the interface on both of the classes. Then just have the parameter type to methoda be the interface instead of the class.