我一直在按照本教程通过 asp.net 中的模式弹出表单实现编辑/更新功能:
http://msdnaspdotnettuto.blogspot.com/2015/01/aspnet-gridview-crud-using-twitter.html
这是我的代码:
public partial class GroupSummary1 : System.Web.UI.Page
{
DataTable dt;
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
LoadGroupSummary();
}
}
private void LoadGroupSummary()
{
try
{
UserBLL userBLL = new UserBLL();
dt = userBLL.GetGroupSummary(2, 2017);
gvGroupSummary.DataSource = dt;
gvGroupSummary.DataBind();
}
catch (SqlException ex)
{
System.Console.Error.Write(ex.Message);
}
}
protected void gvGroupSummary_RowCommand(object sender, GridViewCommandEventArgs e)
{
int index = Convert.ToInt32(e.CommandArgument);
if (e.CommandName.Equals("detail"))
{
string code = gvGroupSummary.DataKeys[index].Value.ToString();
IEnumerable<DataRow> query = from i in dt.AsEnumerable()
where i.Field<int>("GroupID").Equals(code)
select i;
DataTable detailTable = query.CopyToDataTable<DataRow>();
DetailsView1.DataSource = detailTable;
DetailsView1.DataBind();
System.Text.StringBuilder sb = new System.Text.StringBuilder();
sb.Append(@"<script type='text/javascript'>");
sb.Append("$('#detailModal').modal('show');");
sb.Append(@"</script>");
ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "DetailModalScript", sb.ToString(), false);
}
}
}
当我选择网格视图上的"详细信息"按钮时,发生以下错误:
System.ArgumentNullException HResult=0x80004003 Message=Value 不能为空。参数名称:源源 = 堆栈跟踪:
在这一行:
IEnumerable<DataRow> query = from i in dt.AsEnumerable()
where i.Field<int>("GroupID").Equals(code)
select i;
dt 对象为 NULL,我怀疑这是问题的根源。但是,我已经在上面声明了它,就像在教程中一样。
有什么想法吗?
谢谢
LoadGroupSummary
仅在初始页面加载时触发,而不是在回发时触发。单击详细信息按钮以调用gvGroupSummary_RowCommand()
将导致回发。
只需从页面加载中删除if (!IsPostBack)
即可。
protected void Page_Load(object sender, EventArgs e)
{
LoadGroupSummary();
}
编辑:
值得一提的是,如果userBLL.GetGroupSummary()
返回的任何数据都是静态的,则可能只加载一次。例如:
private void LoadGroupSummary()
{
try
{
if (Session["GroupSummary"] != null)
{
dt = (DataTable)Session["GroupSummary"];
}
else
{
UserBLL userBLL = new UserBLL();
dt = userBLL.GetGroupSummary(2, 2017);
Session["GroupSummary"] = dt;
}
gvGroupSummary.DataSource = dt;
gvGroupSummary.DataBind();
}
catch (SqlException ex)
{
System.Console.Error.Write(ex.Message);
}
}