Question

My scenario is: I have a class called MenuBO using linq, it has a function called SelectAll() that returns a list of the object menu to use as a DataSource for a DropDownList. Before returning it I need to insert in the list a new item to serve as a default value for the DropDownList

Here’s what I tried so far:

public List<menu> SelectAll()
{
    using (var db = new SeloQual_AdminEntities(conn))
    {
        menu vmenu = new menu();
        vmenu.cod_menu = 0;
        vmenu.cod_menu_pai = null;
        vmenu.des_menu = "Select...";
        var query = from p in db.menu orderby p.des_menu select p;
        var test = query.ToList();
        test.Add(vmenu);
        return test.OrderBy(x => x.cod_menu).ToList();
    }
}

The OrderBy(x => x.cod_menu) does it job, the vmenu item appears on top like I want, but I need that the other items to be ordered by des_menu. I tried something like

return teste.OrderBy(x => x.cod_menu).ThenBy(y => y.des_menu).ToList();

But didn’t work of course, so I some need help to order only the elements after the first one

Answer 1

I think what you really want is the following code:

menu vmenu = new menu();
vmenu.cod_menu = 0;
vmenu.cod_menu_pai = null;
vmenu.des_menu = "Select...";
var query = from p in db.menu orderby p.des_menu select p;

List<menu> result = new List<menu>();
result.Add(vmenu);
result.AddRange(query);
return result;

This solves your problem elegantly by simply adding the default menu item first and adding the already sorted menu items afterwards in the order defined in the query.