我正试图将用户从中继器生成的控件(复选框、下拉列表、文本框)中选择的内容传递到数据表,并将其用作网格视图的数据源进行测试,最终作为表变量参数传递到存储过程。
如果没有选择某些复选框,则不会生成相应的文本框,并且代码会引发异常(check to determine if the object is empty before calling the method
)。
导致问题的部分似乎是当我将文本从文本框传递到数据表时。当我通过复选框名称时,它运行良好;我试图通过检查是否生成了文本框控件来克服这一问题,但它仍然抛出相同的异常。
是否有更好的方法来检查是否生成了动态文本框?
protected void Button2_Click(object sender, EventArgs e)
{
DataTable Frs = new DataTable("udtMParameters");
Frs.Columns.Add("MName", typeof(string));
Frs.Columns.Add("IsNum", typeof(string));
Frs.Columns.Add("MValue1", typeof(string));
Frs.Columns.Add("MValue2", typeof(string));
try
{
foreach (RepeaterItem i in Repeater1.Items)
{
CheckBox fn = i.FindControl("chk") as CheckBox;
CheckBox isn = i.FindControl("ChkboxIsNumeric") as CheckBox;
PlaceHolder plc = i.FindControl("PlcMFilter") as PlaceHolder;
TextBox s = i.FindControl("start") as TextBox;
TextBox l = i.FindControl("end") as TextBox;
DropDownList d = i.FindControl("value") as DropDownList;
if (fn.Checked)
{
TextBox1.Text = fn.Text;
if (isn.Checked)
{
DataRow dr = Frs.NewRow();
dr["MName"] = fn.Text;
dr["IsNum"] = "Y";
if (String.IsNullOrEmpty(s.Text))
{
dr["MValue1"] = s.Text;
}
else
{
dr["MValue1"] = " ";
}
if (String.IsNullOrEmpty(s.Text))
{
dr["MValue2"] = l.Text;
}
else
{
dr["MValue2"] = " ";
}
Frs.Rows.Add(dr);
}
else
{
DataRow dr = Frs.NewRow();
dr["MName"] = fn.Text;
dr["IsNum"] = "N";
dr["MValue1"] = "MValue1";
dr["MValue2"] = "MValue2";
Frs.Rows.Add(dr);
}
}
this.GridView1.Visible = true;
GridView1.DataSource = Frs;
GridView1.DataBind();
panel2.Enabled = true;
panel2.Visible = true;
}
}
catch (Exception ex)
{
throw ex;
}
}
用括号替换用as实现的强制转换,以便本地化空对象
TextBox s = (TextBox)i.FindControl("start");
TextBox l = (TextBox)i.FindControl("end");
在转换失败的情况下,带括号的强制转换将引发异常,而带as的强制转换会产生null。