在 VB.NET 中获取 HTML 表格行 [英] Getting HTML Table Rows in VB.NET
问题描述
我正在试验 ASP.NET WebForms 和数据.我可以使用在 ASPX 中剪下的一小段代码将数据发布到页面上，但是我无法使用于删除、编辑和查看单个记录的按钮起作用.我相信这是因为我在代码片段中创建表行时无法添加 runat="server".
I am experimenting with ASP.NET WebForms and data. I am able to post data to the page using a small code snipped in the ASPX, but I cannot get the buttons for deleting, editing, and viewing individual records to work. I believe this is because I cannot add runat="server"when I create the table row in the code snippet.
<table id="TBL_Albums" class="table table-striped table-bordered table-responsive">
<thead>
<tr>
<th>ID</th>
<th>Name</th>
<th>Image</th>
<th>Release Date</th>
<th>Price</th>
<th>Genre</th>
<th>Artist</th>
<th># of Tracks</th>
<th colspan="3"> </th>
</tr>
</thead>
<tbody>
<% For Each album In GetAlbums()
%>
<tr>
<td><%=album.AlbumID%></td>
<td>
<span class="text-primary font-weight-bold"><%=album.AlbumName %></span>
</td>
<td>
<img alt='<%=album.AlbumName %>' title='<%=album.AlbumName %>' style="width: 96px;" class="img-fluid" src="../Content/Images/DB/<%=album.ImagePath %>" />
<!-- Path broken for now. Will get fixed when I rearrange pages? -->
</td>
<td><%=album.ReleaseDate.ToString("MMMM yyyy") %></td>
<td><%=album.UnitPrice.ToString("c") %></td>
<td><%=album.Genre.GenreName %></td>
<td><%=album.Band.BandName %></td>
<td><%=album.TotalTracks %></td>
<td>
<asp:Button ID="BTN_Details" runat="server" CssClass="btn btn-block btn-lg btn-info" Text="Details" OnClick="BTN_Details_Click" />
</td>
<td>
<asp:Button ID="BTN_Edit" runat="server" CssClass="btn btn-block btn-lg btn-warning" Text="Edit" OnClick="BTN_Edit_Click" data-toggle="modal" data-target="#EditAlbum" />
</td>
<td>
<asp:Button ID="BTN_Delete" runat="server" CssClass="btn btn-block btn-lg btn-danger" Text="Delete" OnClick="BTN_Delete_Click" />
</td>
</tr>
<%
Next %>
</tbody>
</table>
当我运行项目并单击其中一个按钮时，出现此异常:
When I run the project and click on one of the buttons, I get this exception:
System.InvalidCastException
HResult=0x80004002
Message=Unable to cast object of type 'System.Web.UI.WebControls.ContentPlaceHolder' to type 'System.Web.UI.HtmlControls.HtmlTableRow'.
Source=<Cannot evaluate the exception source>
StackTrace:
<Cannot evaluate the exception stack trace>
我的编辑"按钮代码隐藏如下:
My codebehind for the Edit button looks like this:
Protected Sub BTN_Edit_Click(sender As Object, e As EventArgs)
Dim context As New MusicContext
ClientScript.RegisterStartupScript(Page.GetType(), "EditAlbum", "$('#EditAlbum').modal();", True)
Dim buttonDetails As Button = TryCast(sender, Button)
Dim row As HtmlTableRow = DirectCast(buttonDetails.NamingContainer, HtmlTableRow)
Dim img As HtmlImage = TryCast(row.Cells(2).Controls(0), HtmlImage)
LBL_AlbumToUpdate.Text = row.Cells(1).InnerText
HF_AlbumIDEdit.Value = row.Cells(0).InnerText
TB_EditAlbumName.Text = row.Cells(1).InnerText
IMG_AlbumImage.ImageUrl = img.Src
TB_EditAlbumReleaseDate.Text = CDate(row.Cells(3).InnerText).ToString("yyyy-MM")
TB_EditAlbumPrice.Text = CDec(row.Cells(4).InnerText)
row.Cells(5).InnerText = DDL_EditAlbumGenre.SelectedItem.Text
row.Cells(6).InnerText = DDL_EditAlbumBand.SelectedItem.Text
End Sub
推荐答案
你说得对，这是因为 NamingContainer 是一个 PlaceHolder 而不是 HTMLTableRow.您可以尝试使用 <asp:Table>、<asp:TableRow>、<asp:TableColumn> 控件来代替，但我认为您这样做是错误的.
You are correct, it is because the NamingContainer is a PlaceHolder and not an HTMLTableRow. You can try using <asp:Table>, <asp:TableRow>, <asp:TableColumn> controls instead but I think you're going about this the wrong way.
尝试使用
Instead of iterating with a for each, try using a <asp:Repeater> or <asp:DataList> control. Something like:
<tbody>
<asp:Repeater id="repAlbums" runat="server">
<ItemTemplate>
<tr>
<td>
<asp:Image id="imgAlbumName" ImageUrl="../Content/Images/DB/<%# Eval("ImagePath") %> runat="server" />
</td>
<td>
<asp:Label id="lblReleaseDate" runat="server" Text="<%#Eval("ReleaseDate.ToString("MMMM yyyy")") %>" />
</td>
<td>
<asp:Button ID="BTN_Edit" runat="server" CssClass="btn btn-block btn-lg btn-warning" Text="Edit" data-toggle="modal" data-target="#EditAlbum" CommandName="Edit" />
</td>
</tr>
</ItemTemplate>
</asp:Repeater>
</tbody>
在load事件中绑定Repeater:
Bind the Repeater in the load event:
Me.repAlbums.DataSource = GetAlbums()
Me.repAlbums.DataBind()
然后你将在 Repeater 的 ItemCommand 事件中处理点击事件:
And then you would handle the click event in the Repeater's ItemCommand event:
Private Sub repAlbums_ItemCommand(source As Object, e As RepeaterCommandEventArgs) Handles repAlbums.ItemCommand
If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = ListItemType.AlternatingItem Then
Select Case e.CommandName
Case "Edit"
Dim imgAlbumName As Image = DirectCast(e.Item.FindControl("imgAlbumName"), Image)
Dim lblReleaseDate as Label = DirectCast(e.item.FindControl("lblReleaseDate"), Label)
TB_EditAlbumReleaseDate.Text = CDate(lblReleaseDate.Text).ToString("yyyy-MM")
End Select
End If
End Sub
将您的 td 单元格数据放在标签或文字控件中，以便能够通过背后的代码访问它们.
Put your td cell data within label or literal controls in order to be able to access them via the code behind.
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