c# - gridview e.CommandArgument 字符串格式不正确

Question

我正在尝试将 pdf 从我的数据库带到我的 gridview 并允许用户单击它并下载 pdf。我正在尝试解决此处已解决的问题:

Accessing data from a BoundField of Gridview

但是，我收到以下错误:

Input string was not in a correct format.

这是我的 asp.net 代码:

     <Columns>
         <asp:CommandField ShowEditButton="True" ControlStyle-CssClass="savefile"/>
         <asp:BoundField DataField="ID" HeaderText="ID" InsertVisible="False" 
             ReadOnly="True" SortExpression="ID" />
         <asp:BoundField DataField="event_name" HeaderText="event_name" 
             SortExpression="event_name" />

         <asp:TemplateField HeaderText="PDF">

   <ItemTemplate>
       <asp:Button ID="Button1" ButtonType="Link" CommandName="DownloadFile" HeaderText="Download"  runat="server" Text="Button" />


    </ItemTemplate>

   <EditItemTemplate>

       <asp:FileUpload ID="FileUpload1" runat="server" /> // shown only in edit mode

   </EditItemTemplate>

  </asp:TemplateField>

     </Columns>
 </asp:GridView>

和对应的c#代码:

protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
    {

    if (e.CommandName == "DownloadFile")
    {


        int index = Convert.ToInt32(e.CommandArgument);
        string id = GridView1.DataKeys[index].Value.ToString();
        SqlConnection con = new SqlConnection(strcon);
        string command = "Select pdf from table where id = @id";
        SqlCommand cmd = new SqlCommand(command, con);

        cmd.Parameters.AddWithValue(id, "id");
        SqlDataReader reader = cmd.ExecuteReader();
        reader.Read();
        Response.Clear();
        Response.ContentType = "application/pdf";
        Response.BinaryWrite((Byte[])reader[0]);

        Response.Flush();

        Response.End(); 
    }

}

错误行在我的 C# 代码中是这样的:

int index = Convert.ToInt32(e.CommandArgument);

提前感谢大家的帮助!

编辑-------------------------------------------- ----

我的按钮字段现在看起来像这样:

<asp:Button ID="Button1" ButtonType="Link" CommandName="DownloadFile" CommandArgument='<%#Container.DataItemIndex%>' HeaderText="Download"  runat="server" Text="Button" />

和我的 C# 错误代码行:

int index = Convert.ToInt32(e.CommandArgument);

我仍然收到同样的错误。

Answer 1

您没有指定 CommandArgument。因此，您的错误发生是因为您试图将空白字符串转换为整数。

将行索引添加为您的 CommandArgument:

尝试将其添加到您的 Button 控件中:

<asp:Button ID="Button1"
            ButtonType="Link"
            CommandName="DownloadFile"
            CommandArgument='<%#Container.DataItemIndex%>'
            HeaderText="Download"
            runat="server"
            Text="Button" />