when creating a new boolean column in an existing table how to set the default value as true in csharp models code first

Code Example - when creating a new boolean column in an existing table how to set the default value as true in csharp models code first

                
                        public class Revision
{
    ...
    public Boolean IsReleased { get; set; }
  	public Revision(){
    	IsReleased = true;
    }
    ....
}