How to sort a gridview?

Question

I have a class:

public class CustomInvoice
    {
        public string InvoiceId { get; set; }
        public string Date { get; set; }
        public string RecpDate { get; set; }
        public string Category { get; set; }
        public string TotalValue { get; set; }
        public string InvoiceRef { get; set; }
        public string Client { get; set; }
        public string Status { get; set; }
    }

I populate this class with data and then bind it to my gridview:

List<CustomInvoice> invoices = GetInvoices(url);
InvoiceGrid.DataSource = invoices;         
InvoiceGrid.DataBind();

This displays all of the information correctly, but now i want to be able to sort it, so ive added a button with the following method:

    protected void Button1_Click(object sender, EventArgs e)
    {
        string expression = "InvoiceId";
        SortDirection direction = SortDirection.Ascending;

        InvoiceGrid.Sort(expression,direction);
    }

Ive also changed its html to allow sorting:

<asp:GridView ID="InvoiceGrid" runat="server" AllowSorting="True" OnSorting="gridView_Sorting"></asp:GridView>

However when this runs I get the following exception

System.Web.HttpException (0x80004005): The GridView 'InvoiceGrid' fired event Sorting which wasn't handled.\r\n 

Can someone show me how to sort my gridview by using the onclick of the button?

Thanks :)

edit:

I have tried adding this to the column headers (ignoring the button)

protected void gridView_Sorting(object sender, GridViewSortEventArgs e)
        {
            DataTable dataTable = InvoiceGrid.DataSource as DataTable;
            DataView dataView = new DataView(dataTable);
            dataView.Sort = e.SortExpression + " " + e.SortDirection;

            InvoiceGrid.DataSource = dataView;
            InvoiceGrid.DataBind();
        }

however the problem here is the DataTable is null even though i can see the invoiceGrid has data.

Answer 1

The solution to this problem was mentioned to me by @hamed shams and that is to use linq (which I had completely forgotten about).

So I use linq on my reference to the customInvoice:

var result = from i in invoices
            orderby i.Category ascending
            select i;

Then I bind the result to the gridview:

InvoiceGrid.DataSource = result;
InvoiceGrid.DataBind();

Answer 2

Try this below:

protected void SearchResults_Sorting(object sender, GridViewSortEventArgs e)
{
    var searchedStudents = this.SearchResults();
    var sortedData = searchedStudents.DefaultView;
    var sortDirection = !this.SortDirections.ContainsKey(e.SortExpression) || !this.SortDirections[e.SortExpression] ? "desc" : "asc";
    var sortDirections = new Dictionary<string, bool>();
    sortDirections.Add(e.SortExpression, sortDirection == "desc");
    this.SortDirections = sortDirections;        
    sortedData.Sort = e.SortExpression + " " + sortDirection;
    this.SearchResults.DataSource = sortedData.ToTable();
    this.SearchResults.DataBind();
}

private Dictionary<string, bool> SortDirections
{
    get
    {
        var sortDirection = new Dictionary<string, bool>();
        if (this.ViewState["SortDirection"] != null)
        {
            sortDirection = (Dictionary<string, bool>)this.ViewState["SortDirection"];
        }

        return sortDirection;
    }
    set
    {
        this.ViewState["SortDirection"] = value;
    }

Let me know if you have any questions.