How to set Datetime as current date time in MVC

Question

I have a class as 

//------------------------------------------------------------------------------

// <auto-generated>

// This code was generated from a template.

//

// Manual changes to this file may cause unexpected behavior in your application.

// Manual changes to this file will be overwritten if the code is regenerated.

// </auto-generated>

//------------------------------------------------------------------------------

namespace AdminLteMvc.Models

{

using System;

using System.Collections.Generic;

public partial class Designation

{

public Designation()

{

Date_Created = DateTime.Now;

Date_Modifed = DateTime.Now;

}

}

public int Design_Id { get; set; }

public string Design_Name { get; set; }

public Nullable<bool> IsActive { get; set; }

 public Nullable<DateTime> Date_Created { get ; set ; }

public Nullable<DateTime> Date_Modifed { get ; set ; }

}

}

I want to set datetime as current datetime instead of taking them from users i have also write a constructor and initilizing them in that but still null they are nullable in db as well