ASP.Net即使进入下一页也要对Gridview进行排序

Question

Hi all I am having trouble with the sorting of my gridview. Let's say my gridview has 10 rows of data and 2 columns, Name and Age. Paging is set to 5 rows of data a page. When i click on Name, it is sorted correctly. However when i click on the next page, it becomes "unsorted" again. Help please! I have attached the event handlers below.

    protected void SearchResultGridView_Sorting(object sender, GridViewSortEventArgs e)
    {
        if (ViewState["SearchDS"] == null)
            Response.Redirect("PESearh.aspx");
        DataTable SearchDT = ((DataSet)ViewState["SearchDS"]).Tables[0];

        string sortExpression = e.SortExpression;

        if (ViewState["SearchSort"] != null && ViewState["SearchSort"].ToString().Length > 0)
        {
            if (!ViewState["SearchSort"].ToString().Contains(sortExpression))
                GridViewSortDirection = SortDirection.Descending;
        }
        else
        {
            GridViewSortDirection = SortDirection.Descending;
        }

        if (GridViewSortDirection == SortDirection.Ascending)
        {
            GridViewSortDirection = SortDirection.Descending;
            sortExpression += " DESC";
            SearchDT.DefaultView.Sort = sortExpression;
        }
        else
        {
            GridViewSortDirection = SortDirection.Ascending;
            sortExpression += " ASC";
            SearchDT.DefaultView.Sort = sortExpression;
        }
        ViewState["SearchSort"] = sortExpression;

        this.SearchResultGridView.DataSource = SearchDT;
        this.SearchResultGridView.DataBind();
    }

and for my pagechanging

    protected void SearchResultGridView_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        SearchResultGridView.DataSource = ViewState["SearchDS"];

        SearchResultGridView.PageIndex = e.NewPageIndex;
        SearchResultGridView.DataBind();
    }

I need help so that the previous sorting also sorts the next page. Please help thanks!

Note: I do not want to sort the data before binding because I want the user to see the data first and then decide what to bind.

Answer 1

You seem to be saving the sort expression in ViewState["SearchSort"] . When you change the page index, the value should still remain in the ViewState variable, so you can just grab it and set it again with:

SearchDT.DefaultView.Sort = ViewState["SearchSort"].ToString();

Before sorting the data though, may want to get the DataTable first like so:

DataTable SearchDT = ((DataSet)ViewState["SearchDS"]).Tables[0];

Then, instead of assigning ViewState["SearchDS"] the DataSource of your GridView directly, you can use the new DataTable instead:

SearchResultGridView.DataSource = SearchDT;

Together, you have something like this:

protected void SearchResultGridView_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
    DataTable SearchDT = ((DataSet)ViewState["SearchDS"]).Tables[0];
    SearchDT.DefaultView.Sort = ViewState["SearchSort"].ToString();
    SearchResultGridView.DataSource = SearchDT;

    SearchResultGridView.PageIndex = e.NewPageIndex;
    SearchResultGridView.DataBind();
}

To be safe though, you may want to check to may sure ViewState["SearchSort"] exists first before assigning (if not, then you can give it a default value).