Visual Basic

CType(CallByName(MyObject, "Child1", CallType.Get), HashSet(Of Child1)).ElementAt(k)

Enumerable.ElementAt(CallByName(MyObject, "Child1", CallType.Get), k)

Dim element = Enumerable.ElementAt(CallByName(MyObject, "Child1", CallType.Get), k)

Public Function CopyEntity(Of T As {Class, New})(ctx As MyEntities, entity As T, Optional copyKeys As Boolean = False) As T
       Dim clone As New T()
       Dim en = ctx.Entry(clone)
       en.State = System.Data.Entity.EntityState.Added
       ctx.Entry(clone).CurrentValues.SetValues(entity)
       en.State = System.Data.Entity.EntityState.Detached
       Return clone
   End Function

fhitm = CopyEntity(context, element,False)

An unhandled exception of type 'System.InvalidOperationException' occurred in EntityFramework.dll

Additional information: The entity type Object is not part of the model for the current context.

CTypeDynamic(Element,System.Type.Gettype("Child1"))

System.Type.Gettype("Child1")

Dim element = Enumerable.ElementAt(CallByName(MyObject, "Child1", CallType.Get), k)
REM "element" actually is of the type the elements of Child1 have
REM but at this point it's treated as type Object

REM so this generic function is called for the generic type Object
Public Function CopyEntity(Of T As {Class, New})(ctx As MyEntities, entity As T, ...) As T
    REM so "clone" actually is created as just an Object and not of the same type as "element" / "entity"
    Dim clone As New T()
    REM and the type Object of course isn't a valid entity-type in your context
    Dim en = ctx.Entry(clone)

// CEClass    : class that contains the function CopyEntity
// CEInstance : an instance of CEClass

MethodInfo mi = typeof(CEClass).GetMethod("CopyEntity");
mi = mi.MakeGenericMethod(typeof(MyEntities), element.GetType(), typeof(bool));
// you could cache "mi"

object clone = mi.Invoke(CEInstance, new object[] {context, element, false});

"REM so "clone" actually is created as just an Object and not of the same type as "element" / "entity"

Ctype(element,Child1)

System.Type.Gettype("Child1")

dilkonika wrote:

This is not true because I try to use this instruction :
--- and after that everything works correctly

dilkonika wrote:

the type specified as parameter inside CtypeDynamic

dilkonika wrote:

But where can I find the namespace for my entity object ?

Dim t a type
Dim s  as string = "MyProg1.Child1,MyProg1,Version=1.0.0, Culture=neutral,PublicKeyToken=null"
t=System.Type.GetType(s)

CTypeDynamic(Element,Child1)

Dim t a type
Dim s  as string = "MyProg1.Child1,MyProg1,Version=1.0.0, Culture=neutral,PublicKeyToken=null"
t=System.Type.GetType(s)
CtypeDynamic(Element,t)

An unhandled exception of type 'System.InvalidOperationException' occurred in EntityFramework.dll

Additional information: The entity type Object is not part of the model for the current context.

Dim element = CType(Enumerable.ElementAt(CallByName(MyObj1, "Child1", CallType.Get), k), Child1)

Dim element = CTypeDynamic(Enumerable.ElementAt(CallByName(MyObj1, "Child1", CallType.Get), k), Type.GetType("MyProg1.Child1,MyProg1,Version=1.0.0, Culture=neutral,PublicKeyToken=null"))

Dim el = Enumerable.ElementAt(CallByName(MyClass, "Children", CallType.Get), 1)

REM 1
Dim el1 = CType(el, ChildClass)
Dim el1copy = CopyEntity(el1)   REM works. (el1copy is of type ChildClass)

REM 2
Dim el2 = CTypeDynamic(Of ChildClass)(el)
Dim el2copy = CopyEntity(el2)   REM works. (el2copy is of type ChildClass)

REM 3
Dim el3 = CTypeDynamic(el, GetType(ChildClass))
Dim el3copy = CopyEntity(el3)   REM doesn't work. (el3copy is of type Object)

class ChildClass
{ }

class MyClass
{
    public ICollection<ChildClass> Children { get; set; }

    public MyClass()
    {
        Children = new HashSet<ChildClass>() { new ChildClass() };
    }
}

T CopyEntity<T>(T entity)
    where T : class, new()
{
    T copy = new T();
    // actual copying omitted here
    // for testing only the return type matters
    return copy;
}

void Test()
{
    MyClass myClass = new MyClass();
    dynamic children = typeof(MyClass).GetProperty("Children").GetValue(myClass);
    dynamic child = Enumerable.ElementAt(children, 0);
    dynamic copy = CopyEntity(child);
    // copy is of type ChildClass
}

Class ChildClass
End Class

Class [MyClass]
    Public Property Children() As ICollection(Of ChildClass)
        Get
            Return m_Children
        End Get
        Set
            m_Children = Value
        End Set
    End Property
    Private m_Children As ICollection(Of ChildClass)

    Public Sub New()
        Children = New HashSet(Of ChildClass)() From { _
            New ChildClass() _
        }
    End Sub
End Class

Private Function CopyEntity(Of T As {Class, New})(entity As T) As T
    Dim copy As New T()
    ' actual copying omitted here
    ' for testing only the return type matters
    Return copy
End Function

Private Sub Test()
    Dim [myClass] As New [MyClass]()
    Dim children As dynamic = GetType([MyClass]).GetProperty("Children").GetValue([myClass])
    Dim child As dynamic = Enumerable.ElementAt(children, 0)
    Dim copy As dynamic = CopyEntity(child)
    ' copy is of type ChildClass
End Sub

Dim en = ctx.Entry(clone)

dilkonika wrote:

and this code is not using CTypeDynamic.

Public Class ChildClass
End Class

Public Class SomeClass
    Public Property Children As ICollection(Of ChildClass) = New HashSet(Of ChildClass)
End Class

Public Function CopyEntity(Of T As {Class, New})(entity As T) As T
    Dim clone As New T()
    Return clone
End Function

Sub Main()
    Dim someClass = New SomeClass
    someClass.Children.Add(New ChildClass)

    Dim el = Enumerable.ElementAt(CallByName(someClass, "Children", CallType.Get), 0)

    Dim elcopy = CopyEntity(el)   REM without CTypeDynamic. doesn't work. (elcopy is Object)

    Dim el1 = CType(el, ChildClass)
    Dim el1copy = CopyEntity(el1) REM works (el1copy is ChildClass)

    Dim el2 = CTypeDynamic(Of ChildClass)(el)
    Dim el2copy = CopyEntity(el2) REM works (el2copy is ChildClass)

    Dim el3 = CTypeDynamic(el, GetType(ChildClass))
    Dim el3copy = CopyEntity(el3) REM doesn't work (el3copy is Object)
End Sub

Quote:

and on my vb.net code , the error came up on the line :
Dim en = ctx.Entry(clone)
and you don't have a such line in your code.

dilkonika wrote:

Also I try to implement your version with reflection , but I can't make it work on vb.net ? can you provide some more
help ?

class Program
{
    class ChildClass
    { }

    class SomeClass
    {
        public ICollection<ChildClass> Children { get; set; }

        public SomeClass()
        {
            Children = new HashSet<ChildClass>() { new ChildClass() };
        }
    }

    public static T CopyEntity<T>(T entity)
        where T : class, new()
    {
        T copy = new T();
        return copy;
    }

    static void Main(string[] args)
    {
        SomeClass someClass = new SomeClass();

        dynamic children = typeof(SomeClass).GetProperty("Children").GetValue(someClass);
        object child = Enumerable.ElementAt(children, 0);

        // if CopyEntity would be not a static method, BindingFlags.Instance
        // would have to be used, instead of BindingFlags.Static 
        MethodInfo mi = typeof(Program).GetMethod("CopyEntity", BindingFlags.Static | BindingFlags.Public);
        mi = mi.MakeGenericMethod(new Type[] { /* +typeof(YourContext) */ child.GetType() /* +typeof(bool) */ });

        // if CopyEntity would be not a static method, the first argument
        // to Invoke would have to be the class-instance on which to invoke
        // CopyEntity, instead of null
        object clone = mi.Invoke(null, new object[] { /* +ctx */ child /* +copyKeys */ });
        // -> clone is of type ChildClass
    }
}

Dim clone as New(T)

Dim clone = Activator.CreateInstance(entity.GetType())