Create object instance of a class from its name in string variable

Question

I don't know whether this is possible or not, but I would like to know if it is and, if so, how it works. So here is my question:

I have 2-3 custom model classes of my own. For example, Customer, Employee and Product. I also have a class name in a string. Based on the class name, I want to create an instance and return it to a view. How can I achieve this?

I know that one option is an if/else statement, but I would like a better, dynamic way.

Answer 1

Having the class name in string is not enough to be able to create its instance. As a matter of fact you will need full namespace including class name to create an object.

Assuming you have the following:

string className = "MyClass";
string namespaceName = "MyNamespace.MyInternalNamespace";

Than you you can create an instance of that class, the object of class MyNamespace.MyInternalNamespace.MyClass using either of the following techniques:

var myObj = Activator.CreateInstance(namespaceName, className);

or this:

var myObj = Activator.CreateInstance(Type.GetType(namespaceName + "." + className));

Hope this helps, please let me know if not.

Answer 2

    string frmName = "frmCustomer";
    //WorldCarUI. is the namespace of the form
    Type CAType = Type.GetType("WorldCarUI." + frmName );
    var myObj = Activator.CreateInstance(CAType);
    Form nextForm2 = (Form)myObj;
    nextForm2.Show();

this does works..

Regards Avi

Answer 3

the easiest way is to use Activator. Pass class name to GetType and Create new instance.

ClassInstance s1 = (ClassInstance)Activator.CreateInstance(Type.GetType("App.ClassInstance"));

public class ClassInstance
{
    public string StringData { get; set; }
}

Regards, Nik

Answer 4

Activator class does this job in .net and this technique is very usefull for dependency injection kind of scenarios.

string NameSpace = "ProjectName.YourNameSpace";
string ProbeClass = "CLassName";

ObjectHandle ProberHandle = Activator.CreateInstance(NameSpace, ProbeClass) as ObjectHandle;
ClassName Prober = ProberHandle.Unwrap() as ClassName;

Ensure that you unwrap before type casting otherwise it will give conversion error.