HOW TO: Sort a GridView using List as a datasource

Hey, A few days ago I had post this : HOW TO: Using sorting on GridView without a DataSourceControl, but it was explaining how make this using DataTable as a datasource. I was doing something in a project, when suddenly 🙂 I need to sort a gridview columns, but my datasource was a ListColletion, like this: List<Costumer>, I made a research found out different ways to make the sort works. But the simplest way is this one:

private string ConvertSortDirectionToSql(SortDirection sortDirection)
{

string newSortDirection = string.Empty;

switch (sortDirection) {
case SortDirection.Ascending:
newSortDirection = "ASC";
break;
case SortDirection.Descending:
newSortDirection = "DESC";
break;
}
return newSortDirection;
}

protected void GridView_Sorting(object sender, GridViewSortEventArgs e)
{

string previousSortExpression=(string)ViewState["previousGVSortKey"];
string sortExpression=e.SortExpression;
SortDirection sortDirection = e.SortDirection;

if (sortExpression.Equals(previousSortExpression))
{
sortDirection = SortDirection.Descending;
ViewState["previousGVSortKey"] = string.Empty;
}
else {
ViewState["previousGVSortKey"] = sortExpression;
}

     List<Costumer> list = (List<Costumer>)GridView.DataSource;
     if (list.Count > 0) {
        var query = from c in list
                    select c;

           if (sortDirection == SortDirection.Ascending)
{
if (sortExpression == "FIRST_NAME")
query=query.OrderBy(c => c.FirstName);

if (sortExpression == "LAST_NAME")
query=query.OrderBy(c => c.LastName);

if (sortExpression == "EMAIL")
query = query.OrderBy(c => c.Email);

if (sortExpression == "ADDRESS")
query = query.OrderBy(c => c.Address);
}
else {
if (sortExpression == "FIRST_NAME")
query = query.OrderByDescending(c => c.FirstName);

if (sortExpression == "LAST_NAME")
query = query.OrderByDescending(c => c.LastName);

if (sortExpression == "EMAIL")
query = query.OrderByDescending(c => c.Email);

if (sortExpression == "ADDRESS")
query = query.OrderByDescending(c => c.Address);
}

GridView.DataSource = query.ToList();
GridView.DataBind();
     }
}

I know there are a lot of better way to do that, but for now it is working, maybe I’ll try to make something better.