what is the namespace for IRepository?

private readonly IRepository db;

public JsonResult Users(string term)
{
using (CMSEntities CMS = new CMSEntities())
{

var data = db.Query<studentregistration>()
.Where(r => r.Name.StartsWith(term))
.Select(r => new { r.Id, value = r.Name })
.Take(10)
.ToArray();
return Json(data, JsonRequestBehavior.AllowGet);
}
}


I tried this for autocomplete textbox in mvc2.