Question

I have a gridview that is in an updatepanel. The sort works fine when you click the column headers but if I go to the next page, the sort is lost. I will provide the code below and if ANYONE out there has an idea on how to get out of this mess, please help!

The ShowGrid() function is called in the Page_Load. I am guessing the problem lies with recalling ShowGrid() in the paging function.

 //Show Grid based on argument type
protected void ShowGrid(string arg)
{
    //dataset to hold email addresses
    DataSet ds = new DataSet();
    try
    {
        //open connection with new connection string            
        conn.Open();

        String selectString = String.Format("SELECT * FROM hr_OnlineJobApp"
                     + " WHERE adminCategory='" + adminCategory + "'"
                     + "AND departmentApplyingFor LIKE '" + dept + "' ORDER BY {0} {1}", ViewState["sortExp"], ViewState["sortOrder"]);
        SqlCommand cmd = new SqlCommand(selectString, conn);


        SqlDataAdapter adapter = new SqlDataAdapter(cmd);
        adapter.Fill(ds);

        //bind to gridview
        GridView1.DataSource = ds;
        GridView1.DataBind();

        GridView1.PageIndex = Convert.ToInt32(ViewState["pageIndex"]);
    }
    finally
    {
        if (conn != null)
            conn.Close();
    }
}
 /**********************************************
 * Paging functionality 
 * *******************************************/
protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
    GridView1.PageIndex = e.NewPageIndex;
    //reshow Grid with current type
    adminCategory = GridView1.DataKeys[0]["adminCategory"].ToString();
    ViewState["pageIndex"] = e.NewPageIndex.ToString();
    ShowGrid(adminCategory);
}

/**********************************************
 * Sorting functionality 
 * *******************************************/
protected void gridView_Sorting(object sender, GridViewSortEventArgs e)
{
    string sortExp = e.SortExpression;
    ViewState["sortExp"] = sortExp;
    string sortDir = (string)ViewState["sortOrder"];

    //Changes the sortDir
    if (ViewState["sortOrder"].ToString() == "desc")
    {
        ViewState["sortOrder"] = "asc";
    }
    else
    {
        ViewState["sortOrder"] = "desc";
    }

    try
    {
        conn.Open();
        string sql = "SELECT * FROM hr_OnlineJobApp"
                     + " WHERE adminCategory='" + adminCategory + "'"
                     + "AND departmentApplyingFor LIKE '" + dept + "' ORDER BY " + sortExp + " " + sortDir;


        SqlDataAdapter mySqlAdapter = new SqlDataAdapter(sql, conn);
        DataSet myDataSet = new DataSet();
        mySqlAdapter.Fill(myDataSet);


        GridView1.DataSource = myDataSet;
        GridView1.DataBind();
    }
    finally
    {
        conn.Close();
    }
}

Answer 1

You are setting the PageIndex to 0 in Showgrid:

GridView1.PageIndex = 0;

Therefore you’re overwriting the new value from PageIndexChanging

GridView1.PageIndex = e.NewPageIndex;

So you just don’t need to set the PageIndex in ShowGrid to fix the issue.

Another possible reason for the issue:

Maybe you’re databinding the GridView on every postback from Page_Load. You should do that only at the first time. Use the Page.IsPostBack property:

protected void Page_Load(object sender, System.EventArgs e)
{
   if(!Page.IsPostBack)
       ShowGrid();
}

Last but not least: you are sorting only if the user clicks on the header in gridView_Sorting. You should apply the ORDER BY also in ShowGrid or use only one method to databind your GridView. But you’re always ordering by date desc there.

You should not use a DataView to apply the sort, instead you should use the ORDER BY in the sql at the first place.

String sql = String.Format("SELECT * FROM hr_OnlineJobApp"
                         + " WHERE adminCategory='"+adminCategory+"'"
                         + " ORDER BY {0} {1}", sortExp, sortDir); 
SqlCommand mySqlCommand = new SqlCommand(sql, conn);