Gridview rowdatabound访问数据项目vb [英] Gridview rowdatabound access data items vb

问题描述

我试图将ImageUrl映射到GridView中的模板字段中的图像，但不断收到错误消息：

未将对象引用设置为对象的实例。在这一行上：

Dim imagePath As String = rowView（image_path）

我从来没有做过这之前在一个GridView，但它有一个ListView的工作。

感谢您的任何帮助继承我的代码：

.APSX

 < asp：GridView ID =gvImagesDataKeyNames =idrunat =serverAutoGenerateColumns =FalseBorderWidth =0pxGridLines =None> 
<列> 
< asp：TemplateField> 
< ItemTemplate> 
< asp：CheckBox ID =imageIdrunat =server/> 
< / ItemTemplate> 
< / asp：TemplateField> 
< asp：TemplateField> 
< ItemTemplate> 
< asp：Image ID =imageFilerunat =server>< / asp：Image> 
< / ItemTemplate> 
< / asp：TemplateField> 
< asp：BoundField DataField =id/> 
< /列> 
< / asp：GridView> 
  

后面的代码

  Protected Sub gvImages_RowDataBound（ByVal sender As Object，ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs）处理gvImages.RowDataBound 
 
 Dim rowView As DataRowView = CType（e.Row.DataItem，DataRowView）
 
 Dim imagePath As String = rowView（image_path）
 
 Dim strImageUrl As String =〜/ admin / images /个案/& Request.QueryString（uid）& /& imagePath 
 
 Dim imageFile As System.Web.UI.WebControls.Image = CType（e.Row.FindControl（imageFile），System.Web.UI.WebControls.Image）
 imageFile .ImageUrl = strImageUrl 
 
 End Sub 
  

解决方案

我想你需要检查它的数据行而不是标题行

试试这个

  Protected Sub gvImages_RowDataBound（ByVal sender As Object，ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs）处理gvImages.RowDataBound 
 
如果e.Row.RowType = DataControlRowType.DataRow Then 
 
 Dim rowView As DataRowView = CType（e.Row.DataItem，DataRowView）
 
 Dim imagePath As String = rowView（image_path）
 
 Dim strImageUrl As String =〜/ admin / images / cases /& Request.QueryString（uid）& /& imagePath 
 
 Dim imageFile As System.Web.UI.WebControls.Image = CType（e.Row.FindControl（imageFile），System.Web.UI.WebControls.Image）
 imageFile .ImageUrl = strImageUrl 
 
 End If 
 End Sub 
  

I am trying to an ImageUrl to an image in a Template Field in GridView but keep getting the error:

Object reference not set to an instance of an object. on this line:

Dim imagePath As String = rowView("image_path")

I've never done this before on a GridView but had it working on a ListView.

Thanks for any help heres my code:

.APSX

        <asp:GridView ID="gvImages" DataKeyNames="id" runat="server" AutoGenerateColumns="False" BorderWidth="0px" GridLines="None">
        <Columns>
            <asp:TemplateField>
                <ItemTemplate>
                    <asp:CheckBox ID="imageId" runat="server" />
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField>
                <ItemTemplate>
                    <asp:Image ID="imageFile" runat="server"></asp:Image>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:BoundField DataField="id" />
        </Columns>
    </asp:GridView>

CODE BEHIND

Protected Sub gvImages_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles gvImages.RowDataBound

    Dim rowView As DataRowView = CType(e.Row.DataItem, DataRowView)

    Dim imagePath As String = rowView("image_path")

    Dim strImageUrl As String = "~/admin/images/cases/" & Request.QueryString("uid") & "/" & imagePath

    Dim imageFile As System.Web.UI.WebControls.Image = CType(e.Row.FindControl("imageFile"), System.Web.UI.WebControls.Image)
    imageFile.ImageUrl = strImageUrl

End Sub

解决方案

I think you need to check that its a data row and not the header row

Try this

Protected Sub gvImages_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles gvImages.RowDataBound

    If e.Row.RowType = DataControlRowType.DataRow Then

        Dim rowView As DataRowView = CType(e.Row.DataItem, DataRowView)

        Dim imagePath As String = rowView("image_path")

        Dim strImageUrl As String = "~/admin/images/cases/" & Request.QueryString("uid") & "/" & imagePath

        Dim imageFile As System.Web.UI.WebControls.Image = CType(e.Row.FindControl("imageFile"), System.Web.UI.WebControls.Image)
        imageFile.ImageUrl = strImageUrl

    End If
End Sub

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