对 gridview 排序后的链接按钮命令参数错误

Question

在 GridView 的 asp:TemplateField 列中，我有一个 LinkBut​​ton，它将命令参数传递给一个函数，该函数在单击该行时将其删除。但是，GridView 排序后，LinkBut​​ton 传递了错误的参数。此外，GridView 会丢失排序顺序。

我做错了什么？

这是我的代码：

<!---master page---->
<asp:GridView runat="server" ID="companies_grid" AllowSorting="true"
    AutoGenerateColumns="false" OnSorting="companies_grid_OnSorting"
    OnRowDataBound="companies_grid_OnRowDataBound" >
        <Columns>
            <%--Company Name--%>
            <asp:TemplateField HeaderText="Company Name" SortExpression="Name">
                <ItemTemplate>
                    <asp:LinkButton ID="LinkButton1" runat="server"
                         OnClick="removeCompany_click" />
                     <a href='<%#Eval("URL")%>'><%#Eval("Name")%></a>
                </ItemTemplate>
             </asp:TemplateField>
            //more columns

<!---code behind---->
    protected void Page_Load(object sender, EventArgs e)
    {
        companies = GetCompanyData();

        companies_grid.DataSource = companies;
        companies_grid.DataBind();
    }

    protected void companies_grid_OnSorting(object sender, GridViewSortEventArgs e)
    {
        //sort is made up of column to sort by + direction
        companies.DefaultView.Sort = e.SortExpression.ToString() + " " + GetSortDirection(e.SortExpression, "companiesExpression", "companiesDirection");
        companies_grid.DataSource = companies;
        companies_grid.DataBind();

    }

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

        // Retrieve the last column that was sorted.
        string sortExpression = ViewState[expressionViewState] as string;

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

        // Save new values in ViewState.
        ViewState[directionViewState] = sortDirection;
        ViewState[expressionViewState] = column;

        return sortDirection;
    }

    protected void companies_grid_OnRowDataBound(Object Sender, GridViewRowEventArgs e)
    {
        GridViewRow currRow = e.Row;

        if (currRow.RowType == DataControlRowType.DataRow)
        {
            LinkButton deleteCompButton = (LinkButton)e.Row.FindControl("LinkButton1") as LinkButton;
            deleteCompButton.CommandArgument = ((DataRowView)e.Row.DataItem)["Company_ID"].ToString();
            deleteCompButton.Text = ((DataRowView)e.Row.DataItem)["Company_ID"].ToString();
        }
    }

    protected void removeCompany_click(Object sender, EventArgs e)
    {
        bool removeSuccess = false;

        string idToDelete = ((LinkButton)sender).CommandArgument as string;
        removeSuccess = UserInfo.DeleteCompany(idToDelete);
        if (removeSuccess)
        {
            Response.Redirect(Request.RawUrl);
        }
    }

Answer 1

这就是问题所在：

当点击 LinkBut​​ton 时，首先发生的是页面重新加载。但是，Response.Redirect(Request.RawUrl) 不保留 ViewState，因此排序顺序丢失。因此，GridView 将重新填充未排序的数据。

然后，LinkBut​​ton onClick 事件函数被调用。传入的 Object 是来自正确行号的 LinkBut​​ton，但由于表的排序顺序已更改（恢复到未排序状态），该行中的 LinkBut​​ton 不再是用户单击的 LinkBut​​ton。因此，命令参数是错误的。

解决问题：

我把所有的 ViewState[string] 都改成了 Session[string] （这样在页面重新加载的时候会保留排序方向），并在绑定 GridView 之前在 Page_Load 函数中添加了如下代码：

if (Session["companiesExpression"] != null 
     && Session["companiesDirection"] != null)
{
     companies.DefaultView.Sort = Session["companiesExpression"] + " " +
          Session["companiesDirection"];
 }