Question

在下面的代码中，我有一个网格视图，当我尝试分页时，我有数据，它会在链接按钮中抛出错误，无法转换类型为＆＃39; System.Web.UI.WebControls.GridView＆＃39的对象;键入＆＃39; System.Web.UI.WebControls.LinkButton.pls帮助我解决问题。

protected void Attchdwnld_RowCommand(object sender, GridViewCommandEventArgs e)
        {

            var row = ((LinkButton)e.CommandSource).NamingContainer as GridViewRow;
            var attachmentNameLabel = row.FindControl("AttachmentFileName") as Label;
           // var SearchDoc = (SearchDoc)Session["Documentname"]; 
            lblMessage.Text = attachmentNameLabel.Text;


            string fileurl = "C:\\Search\\" + strClientName + "\\" + strAttachmentFolder + "\\" + lblMessage.Text;
            string filename = fileurl;
            if (filename != "")
            {
                string path = filename;
                System.IO.FileInfo file = new System.IO.FileInfo(path);
                if (file.Exists)
                {
                    Response.Clear();
                    Response.AddHeader("Content-Disposition", "attachment; filename=" + file.Name);
                    Response.AddHeader("Content-Length", file.Length.ToString());
                    Response.ContentType = "application/octet-stream";
                    Response.WriteFile(file.FullName);
                    Response.End();
                }
                else
                {
                    Response.Write("This file does not exist.");
                }
            }
            var SearchDoc = (SearchDoc)Session["Documentname"];
            string odoc = SearchDoc.DocumentID.ToString();
            DocumentServiceClient Doc = new DocumentServiceClient();
            DataTable dtAttachment = Doc.GetDocumentsByDocumentID(odoc).Tables[0];
            Attchdwnld.DataSource = dtAttachment;
            Attchdwnld.DataBind();
        }

<asp:GridView Width="100%" runat="server" ID="Attchdwnld" AutoGenerateColumns="false" CellPadding="4" ForeColor="#333333" ShowFooter="false" 
                  PageSize-Mode="NumericPages" PageSize="1" PagerStyle-Visible="true" OnPageIndexChanging="Attchdwnld_PageIndex" AllowPaging="true" AllowSorting="true"  
          OnRowCommand="Attchdwnld_RowCommand"
                    CssClass="mGrid"
                    PagerStyle-CssClass="pgr" AlternatingRowStyle-CssClass="alt">
                  <Columns>
                  <asp:TemplateField HeaderText="DocumentID" ItemStyle-Width="200px" Visible="false"  >              
                  <ItemTemplate>                                              
                    <asp:Label ID="DocumentID"  runat="server"  Text='<%#Eval("DocumentID") %>'> </asp:Label>
                  </ItemTemplate> 
                  </asp:TemplateField>

                  <asp:TemplateField HeaderText="AttachmentFileName" ItemStyle-Width="200px"  >              
                <ItemTemplate>                                              
                    <asp:Label ID="AttachmentFileName"  runat="server"  Text='<%#Eval("AttachmentFileName") %>'> </asp:Label>
                </ItemTemplate> 
                </asp:TemplateField>
                 <asp:TemplateField HeaderText="DownLoad" itemstyle-width="150px">
                            <ItemTemplate>
                                <asp:LinkButton ID="btnEdit" runat="server" CommandName="View" Text="Download"  CausesValidation="false"/>

                            </ItemTemplate>     
                        </asp:TemplateField>       

        </Columns>

                     <HeaderStyle Font-Bold="True" ForeColor="White" />
    </asp:GridView>

Answer 1

RowCommand事件可能是由GridView中的许多操作引起的（分页，排序，删除，e.t.c。）。您必须使用CommandName来区分事件，例如，您可以尝试：

protected void Attchdwnld_RowCommand(object sender, GridViewCommandEventArgs e)
        {
          if (e.CommandName == "View")
          { 
            var row = ((LinkButton)e.CommandSource).NamingContainer as GridViewRow;
            var attachmentNameLabel = row.FindControl("AttachmentFileName") as Label;
           // var SearchDoc = (SearchDoc)Session["Documentname"]; 
            lblMessage.Text = attachmentNameLabel.Text;


            string fileurl = "C:\\Search\\" + strClientName + "\\" + strAttachmentFolder + "\\" + lblMessage.Text;
            string filename = fileurl;
            if (filename != "")
            {
                string path = filename;
                System.IO.FileInfo file = new System.IO.FileInfo(path);
                if (file.Exists)
                {
                    Response.Clear();
                    Response.AddHeader("Content-Disposition", "attachment; filename=" + file.Name);
                    Response.AddHeader("Content-Length", file.Length.ToString());
                    Response.ContentType = "application/octet-stream";
                    Response.WriteFile(file.FullName);
                    Response.End();
                }
                else
                {
                    Response.Write("This file does not exist.");
                }
            }
            var SearchDoc = (SearchDoc)Session["Documentname"];
            string odoc = SearchDoc.DocumentID.ToString();
            DocumentServiceClient Doc = new DocumentServiceClient();
            DataTable dtAttachment = Doc.GetDocumentsByDocumentID(odoc).Tables[0];
            Attchdwnld.DataSource = dtAttachment;
            Attchdwnld.DataBind();
          }
        }

其中CommandName == "View"是您链接按钮的命令。

Answer 2

错误显然在这里：

 var row = ((LinkButton)e.CommandSource).NamingContainer as GridViewRow;

原因是e.CommandSource实际上属于GridView类型而非类型LinkButton。您需要将行更改为：

 var row = (GridView)e.CommandSource;

上面的代码将摆脱你所获得的ClassCastException，但我不确定它是否会使你的代码按预期运行。我建议你改用这个策略：

在CommandArgument：

中设置行索引

<asp:TemplateField HeaderText="DownLoad" itemstyle-width="150px">
                        <ItemTemplate>
                            <asp:LinkButton ID="btnEdit" runat="server" CommandName="View"   Text="Download"  CausesValidation="false" 
CommandArgument='<%# Container.DataItemIndex %>'/>
                        </ItemTemplate>     
 </asp:TemplateField>

现在在您的代码中，只需执行此操作：

protected void Attchdwnld_RowCommand(object sender, GridViewCommandEventArgs e)
{
   int index = Convert.ToInt32(e.CommandArgument);

  // Retrieve the row that contains the button clicked
  // Use the CommandSource property to access the GridView control.
  GridView yourGrid = (GridView)e.CommandSource;
  GridViewRow row = yourGrid.Rows[index];
  // rest of your code... you now have the instance of the row that fired the event.

网格视图中的分页引发错误

2 个答案: