使用DataTable作为数据源的GridView排序事件处理

Question

I have a GridView which Id is GridView1 inside a updatePanel, I have defined programatically most of the events, but I havent issues while creating the event handler for sorting, can you kindly look my code and suggest the way to implement the sortings event using the datatable below?

// Method to BinData to GridView1

private void BindData()
     {
         string strQuery = "SELECT * FROM [tbl_SignIns] ";
         SqlCommand cmd = new SqlCommand(strQuery);
         GridView1.DataSource = GetData(cmd);
         GridView1.DataBind();
     }

     private DataTable GetData(SqlCommand cmd)
     {
         DataTable dt = new DataTable();
         SqlConnection con = new SqlConnection(strConnString);
         SqlDataAdapter sda = new SqlDataAdapter();
         cmd.CommandType = CommandType.Text;
         cmd.Connection = con;
         con.Open();
         sda.SelectCommand = cmd;
         sda.Fill(dt);
         return dt;
     }


 protected void GridView1_Sorting(object sender, GridViewSortEventArgs e)
     {

?????????????????????????????????

     }

Answer 1

I had a same problem and i solve like this. First I added up and down arrow on gridview header.

     <asp:TemplateField FooterText="Toplam" HeaderText="---">
 <HeaderTemplate>
 <asp:Label ID="Label4" runat="server" Text="---"></asp:Label><br />
 <br />
 <div id="myelement">
 <asp:ImageButton ID="btnDateUp" runat="server" ImageUrl="~/Admin/skins/Skin_1/images/grid_uparrow.png"
 OnClick="btnDateUp_Click" />
 <asp:ImageButton ID="btnDateDown" runat="server" ImageUrl="~/Admin/skins/Skin_1/images/grid_downarrow.png"
 OnClick="btnDateDown_Click" Style="width: 16px" />
 </div>
 </HeaderTemplate>
 <ItemTemplate>
 <asp:Label ID="Label3" runat="server" Text='<%# Bind("OrderDate", "{0:D}") %>'></asp:Label>
 </ItemTemplate>
 <ItemStyle HorizontalAlign="Left" Width="210px" />
 </asp:TemplateField>

After, I prepared my sql query like this ;

protected void btnDateUp_Click(object sender, ImageClickEventArgs e)
    {
        sortingQuery = " ORDER BY OrderDate DESC ";
        if (radioListReport.SelectedValue == "1")
            SortGrid();
        else
            SortQuarterGrid();

        updatePanelGrid.Update();
    }

protected void btnDateDown_Click(object sender, ImageClickEventArgs e)
    {
        sortingQuery = " ORDER BY OrderDate ASC ";
        if (radioListReport.SelectedValue == "1")
            SortGrid();
        else
            SortQuarterGrid();

        updatePanelGrid.Update();
    }

I hope it ll help you.

Answer 2

You will have to create tow viewstates one for the sort direction and the other for sort expression for checking while sorting.

First, Sort Direction is retrieved from gridview as "Ascending" and "Descending" and when you want to filer data in the datatable you have to use "ASC" and "DESC" that passes the gridview sort direction and then retirevs it's according value when sorting the datable.

Second, A flip function that will passes a the sort direction and will flip it, and it's used when you click the first time on the columon it will sort "ASC" for example then the second time you click on it, it have to be "DESC" thats why i flip it.

Third, Viewstates are used to withhold the values of the previous sort.

Fourth, Create a viewstate to hold the sort datatable for PageIndexChanging event, ofcourse you will have to check if the viewstate is null then you will have to fetch data and bind it, else you will have to bind the gridview with sorted datatable.

protected void GridView_Users_Sorting(object sender, GridViewSortEventArgs e)
{
    if (String.IsNullOrEmpty(ViewState["sortExpression"].ToString()) && String.IsNullOrEmpty(ViewState["sortDirection"].ToString()))
    {
      //Sort and bind data as ASCENDING for the first time
      DefaultSortBind(e);
    }
    else
    {
        if (ViewState["sortExpression"].ToString() == e.SortExpression.ToString())
        {
            string sortDirection = string.Empty;
            if (ViewState["sortDirection"].ToString() == e.SortDirection.ToString())
            {
                sortDirection = flipSortDirection(GetSortDirection(e.SortDirection.ToString()));
            }
            else
            {
                sortDirection = GetSortDirection(e.SortDirection.ToString());
            }

            DataTable dt = new UserInfoTableTableAdapter().GetData();
            dt.DefaultView.Sort = e.SortExpression + " " + sortDirection;
            GridView_Users.DataSource = dt.DefaultView;
            GridView_Users.DataBind();
            ViewState["sortedDt"] = dt.DefaultView.ToTable();
            ViewState["sortDirection"] = sortDirection;
        }
        else
        {
            //Sort and bind data as ASCENDING
            DefaultSortBind(e);
        }
    }
}

    private void DefaultSortBind(GridViewSortEventArgs e)
{
    ViewState["sortExpression"] = e.SortExpression;
    ViewState["sortDirection"] = e.SortDirection;
    //Fetch data again, because if we try to get data from gridview it will give null
    DataTable dt = new UserInfoTableTableAdapter().GetData();
    dt.DefaultView.Sort = e.SortExpression + " " + GetSortDirection(e.SortDirection.ToString());
    GridView_Users.DataSource = dt.DefaultView;
    GridView_Users.DataBind();
    ViewState["sortedDt"] = dt.DefaultView.ToTable();
}

    //Get sort direction
private string GetSortDirection(string sortDirection)
{
    if (sortDirection == "Ascending")
    {
        return "ASC";
    }
    else
    {
        return "DESC";
    }
}

//Flip sort direction
private string flipSortDirection(string sortDirection)
{
    if (sortDirection == "ASC")
    {
        return "DESC";
    }
    else
    {
        return "ASC";
    }
}