GridView.Row.Count总是0，如何解决？

Question

我是ASP.NET新手。我使用GridView。当我计算GridView的行时，它总是显示0。我在给代码。但是当我运行代码浏览器时，它会显示数据。怎么解决这个问题？

我的CS代码是：

protected void btnSend_OnClick(object sender, EventArgs e)
    {
        string MemberList= (ViewState["Memberlist"]).ToString();
        List<PreparedEmail> preparedEmail = new List<PreparedEmail>();
        Utility util = new Utility();
        int count = 0;

        int i1 = dlClients.Rows.Count; // it shows always 0
        #region Send Invitation
        foreach (GridViewRow mail in dlClients.Rows)
        {
          //some code here, It is never execute as dlClients.Rows shows 0
         }                            
}

我的aspx代码是：

<asp:GridView ID="dlClients" EnableViewState="false" runat="server" AutoGenerateColumns="False" ClientIDMode="Static" GridLines="None" AllowPaging="false" CssClass="table table-bordered table-striped" OnPreRender="dlClients_PreRender" DataKeyNames="MemberId" PageSize="10" ShowHeader="true"> 

我的数据绑定代码：

Protected void dlClients_PreRender(object sender, EventArgs e)
    {
        List<CircleUser> memberList = new CircleUserBusinessLogic().GetAll();
        dlClients.DataSource = memberList;

        dlClients.DataBind();
        //GridUpdatePanel.Update();
        ViewState["Memberlist"] = memberList;

        if (dlClients.Rows.Count > 0)
        {
            //Replace the <td> with <th> and adds the scope attribute
            dlClients.UseAccessibleHeader = true;

            //Adds the <thead> and <tbody> elements required for DataTables to work
            dlClients.HeaderRow.TableSection = TableRowSection.TableHeader;

            //Adds the <tfoot> element required for DataTables to work
            dlClients.FooterRow.TableSection = TableRowSection.TableFooter;
        }
    }

Answer 1

通常首先调用asp按钮单击事件，然后触发gridview预渲染。因此Gridview行数为0。

尝试在PageLoad方法或按钮单击中绑定gridview。

这里示例绑定...

protected void Page_Load(object sender, EventArgs e)
        {
            if(!IsPostBack )
            {
                DataTable dt = new DataTable();
                dt = GetData();
                dlClients.DataSource = dt;

                dlClients.DataBind();
            }
        }

Answer 2

在button_click事件之前调用prerender事件。这意味着，当按钮单击事件正在运行时，databind尚未运行，因此GridView为空。要解决此问题，您可以在页面的load事件中进行数据绑定。这是在点击事件之前调用的。

Answer 3

在Button PreRender事件中调用Gridview click事件，如下所示：

        protected void btnSend_OnClick(object sender, EventArgs e)
        {
            dlClients_PreRender(sender, args);
            string MemberList = (ViewState["Memberlist"]).ToString();
            List<PreparedEmail> preparedEmail = new List<PreparedEmail>();
            Utility util = new Utility();
            int count = 0;

            int i1 = dlClients.Rows.Count;             
            foreach (GridViewRow mail in dlClients.Rows)
            {
                //some code here, It is never execute as dlClients.Rows shows 0
            }
        }

Answer 4

EnableViewState = "true"是一种将数据从一个页面传递到另一个页面的方法