Gridview rowdatabound access data items vb - asp.net

Question

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

Answer 1

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

Answer 2

try
Dim imagePath As String = e.rowView("image_path").ToString()
If the table binded with the grid has column "image_path", then instead use an easier way....
<asp:Image id="img1" runat="server" imageUrl = '<%#Eval("image_path")%>' />
If you want to build some custome string
imageurl = '<%# String.Format("{0} - {1} - {2} - {3}", Eval("Name1"), Eval("Name2"), Session["abc"],Request["abc"]) %>'