c# - 在类里面对 gridview 进行排序

Question

好的，我有一个项目，它的页面中有很多 gridview...现在我正在使用这样的排序函数对 fridveiw 进行排序:

    protected void GridView1_Sorting(object sender, GridViewSortEventArgs e)
    {
        DataTable dt = Session["TaskTable2"] as DataTable;

        if (dt != null)
        {

            //Sort the data.
            dt.DefaultView.Sort = e.SortExpression + " " + GetSortDirection(e.SortExpression);
            GridView1.DataSource = Session["TaskTable2"];
            GridView1.DataBind();
        }

    }

    private string GetSortDirection(string column)
    {
        // By default, set the sort direction to ascending.
        string sortDirection2 = "ASC";

        // Retrieve the last column that was sorted.
        string sortExpression2 = ViewState["SortExpression2"] as string;

        if (sortExpression2 != null)
        {
            // Check if the same column is being sorted.
            // Otherwise, the default value can be returned.
            if (sortExpression2 == column)
            {
                string lastDirection = ViewState["SortDirection2"] as string;
                if ((lastDirection != null) && (lastDirection == "ASC"))
                {
                    sortDirection2 = "DESC";
                }
            }
        }

        // Save new values in ViewState.
        ViewState["SortDirection2"] = sortDirection2;
        ViewState["SortExpression2"] = column;

        return sortDirection2;
    }

但这段代码在许多页面中重复出现，所以我试图将此函数放在 C# 类中并尝试调用它，但出现错误....

对于初学者，我收到 View 状态错误:|

“ View 状态在当前上下文中不存在”

那么我该怎么做......？

谢谢

这就是我类的内容:

public string GetSortDirection(string column)
    {
        // By default, set the sort direction to ascending.
        string sortDirection2 = "ASC";

        // Retrieve the last column that was sorted.
        string sortExpression2 = ViewState["SortExpression2"] as string;

        if (sortExpression2 != null)
        {
            // Check if the same column is being sorted.
            // Otherwise, the default value can be returned.
            if (sortExpression2 == column)
            {
                string lastDirection = ViewState["SortDirection2"] as string;
                if ((lastDirection != null) && (lastDirection == "ASC"))
                {
                    sortDirection2 = "DESC";
                }
            }
        }

        // Save new values in ViewState.
        ViewState["SortDirection2"] = sortDirection2;
        ViewState["SortExpression2"] = column;

        return sortDirection2;
    }

我是这样从我的代码中调用它的:

 protected void GridView1_Sorting(object sender, GridViewSortEventArgs e)
    {
        DataTable dt = Session["TaskTable2"] as DataTable;

        if (dt != null)
        {

            //Sort the data.
            dt.DefaultView.Sort = e.SortExpression + " " + new impersonateClass().GetSortDirection(e.SortExpression);
            GridView1.DataSource = Session["TaskTable2"];
            GridView1.DataBind();
        }

    }

我得到 View 状态错误...

这是一种将整个事情放在类里面的方法...因为到处都在重复...

Answer 1

您需要传入 ViewState，因为 ViewState 对象是 Page 类的成员。一旦您将代码移至单独的类中，它就无法再访问 ViewState 对象。

public string GetSortDirection(string column, StateBag viewState) {
    // Your code here.
}