[英]Getting HTML Table Rows in VB.NET
我正在试验ASP.NET WebForms和数据。 我能够使用ASPX中的一小段代码将数据发布到页面上,但是我无法使用删除,编辑和查看单个记录的按钮来工作。 我相信这是因为在代码片段中创建表行时无法添加runat="server"
。
<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按钮之一时,出现此异常:
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”按钮的代码如下:
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
您是正确的,这是因为NamingContainer是PlaceHolder而不是HTMLTableRow。 您可以尝试使用<asp:Table>, <asp:TableRow>, <asp:TableColumn>
控件,但是我认为您使用的是错误的方式。
与其对每个变量进行迭代,不如尝试使用<asp:Repeater>
或<asp:DataList>
控件。 就像是:
<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>
在重载事件中绑定Repeater:
Me.repAlbums.DataSource = GetAlbums()
Me.repAlbums.DataBind()
然后,您将在Repeater的ItemCommand事件中处理click事件:
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td单元格数据放入标签或文字控件中,以便能够通过后面的代码访问它们。
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