无法投类型的对象'System.Web.UI.LiteralControl“错误 [英] Unable to cast object of type ‘System.Web.UI.LiteralControl’ Error

问题描述

我得到这个错误：
无法投类型的对象System.Web.UI.LiteralControl为键入'System.Web.Controls.TextBox

I am getting this error: Unable to cast object of type ‘System.Web.UI.LiteralControl’ to type ‘System.Web.Controls.TextBox’

我从ASPX页面查询字符串喂我的文本输入框，这里是code：

I am feeding my Text input box from a querystring in the ASPX page and here is the code:

<EditItemTemplate>
                        <asp:TextBox ID="GV_Post_ID" runat="server" text='<%# Request.QueryString["Post_ID"] %>'></asp:TextBox>
                    </EditItemTemplate>

但是当我运行它，它止于此：

But when I run it, it stops here:

cmd.Parameters.Add("@Post_ID", SqlDbType.VarChar).Value = ((TextBox)GV_InlineEditing.Rows[0].Cells[2].Controls[0]).Text;

和我得到上述错误。这里是code背后：

and I get the error above. Here is the code behind:

SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["DSRConnectionString"].ConnectionString);
            SqlCommand cmd = new SqlCommand();
            cmd.CommandText = "INSERT INTO RCA_Events(Post_ID, Date, Description) VALUES(@Post_ID, @Date, @Description)";
            cmd.Parameters.Add("@Post_ID", SqlDbType.VarChar).Value = ((TextBox)GV_InlineEditing.Rows[0].Cells[2].Controls[0]).Text;
            cmd.Parameters.Add("@Date", SqlDbType.VarChar).Value = ((TextBox)GV_InlineEditing.Rows[0].Cells[3].Controls[0]).Text;
            cmd.Parameters.Add("@Description", SqlDbType.VarChar).Value = ((TextBox)GV_InlineEditing.Rows[0].Cells[4].Controls[0]).Text;

请注意，如果我从ASPX页面中删除查询字符串，然后我将值手动，然后它的作品。 PLS。帮帮我。
谢谢

Please note if I remove the querystring from the ASPX page and then I insert the value manually then it works. Pls. help. thanks

推荐答案

该问题是在这里：

（文本框）GV_InlineEditing.Rows [0] .Cells [2] .Controls [0]

在单元格中的第一个控制不是文本框你认为它是。让我们假设 GV_InlineEditing.Rows [0] 被安全地得到你所需要的行。做这样的事情：

The first control in that cell isn't the TextBox you think it is. Let's assume GV_InlineEditing.Rows[0] is safely getting you the row you need. Do something like this:

TextBox myTextBox = GV_InlineEditing.Rows[0].FindControl("GV_Post_ID") as TextBox;
cmd.Parameters.Add("@Post_ID", SqlDbType.VarChar).Value = myTextBox.Text;

这code可以更加安全的是这样的：

That code can be even more safe like this:

TextBox myTextBox = GV_InlineEditing.Rows[0].FindControl("GV_Post_ID") as TextBox;
if (myTextBox != null)
{
    cmd.Parameters.Add("@Post_ID", SqlDbType.VarChar).Value = myTextBox.Text;
}
else
{
    // Do something here.  Default value for the post id?
}

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