Solved

Object reference not set to an instance of an object.

Posted on 2013-05-22
2
548 Views
Last Modified: 2013-06-03
In button click event, I got this error. I am not sure why.
Object reference not set to an instance of an object.


  Dim filename As String
   
  filename = Me.FileUpload1.PostedFile.FileName
code.txt
0
Comment
Question by:VBdotnet2005
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 23

Expert Comment

by:Ioannis Paraskevopoulos
ID: 39191321
Hi,

Try the following code:
        filename = CType(Page.FindControl("FileUpload1"), FileUpload).PostedFile.FileName

Open in new window


Giannis
0
 
LVL 12

Accepted Solution

by:
jitendra patil earned 500 total points
ID: 39193921
Hi

The problem lies in your aspx code.

You need to add a trigger to your update panel as given below
</ContentTemplate>
            <Triggers>
              <asp:PostBackTrigger ControlID="btnUpload" />
            </Triggers>
        </asp:UpdatePanel>


view the complete code here
<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">
   
    <div>
        <asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
        <asp:UpdatePanel ID="UpdatePanel_1" runat="server">
            <ContentTemplate>
                <table>
                    <tr>
                        <td>
                            Upload File
                            <asp:FileUpload ID="FileUpload1" runat="server" Size="100" />&nbsp;&nbsp;
                            <asp:Button ID="btnUpload" runat="server" Text="Upload" />
                            &nbsp;<br />
                        </td>
                    </tr>
                    <tr>
                        <td>
                            <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" CellPadding="4"
                                DataKeyNames="ID" DataSourceID="SqlDataSource1" ForeColor="#333333" GridLines="Vertical"
                                HorizontalAlign="Center" Width="100%">
                                <RowStyle BackColor="#F7F6F3" ForeColor="#333333" />
                                <Columns>
                                    <asp:TemplateField>
                                        <ItemTemplate>
                                            <asp:CheckBox ID="CheckBox1" runat="server" />
                                        </ItemTemplate>
                                    </asp:TemplateField>
                                    <asp:BoundField DataField="CustomerID" HeaderText="CustomerID" SortExpression="CustomerID" />
                                    <asp:TemplateField HeaderText="filename">
                                        <ItemTemplate>
                                            <asp:HyperLink ID="HyperLink1" runat="server" NavigateUrl='<%# string.format("test.aspx?={0}", Databinder.Eval(container.Dataitem, "filename")) %>'
                                                Text='<%# Databinder.Eval(container.dataitem, "filename") %>'></asp:HyperLink>
                                        </ItemTemplate>
                                    </asp:TemplateField>
                                    <asp:BoundField DataField="ID" HeaderText="ID" SortExpression="ID" Visible="false" />
                                    <asp:BoundField DataField="map_client" HeaderStyle-HorizontalAlign="Center" HeaderText="Map Columns"
                                        ItemStyle-HorizontalAlign="Center" Visible="true" />
                                </Columns>
                                <FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
                                <PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
                                <SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
                                <HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" HorizontalAlign="Left" />
                                <EditRowStyle BackColor="#999999" />
                                <AlternatingRowStyle BackColor="White" ForeColor="#284775" />
                                <EmptyDataTemplate>
                                    <table bgcolor="#5D7B9D" style="width: 100%; border-style: solid; border-width: 1px">
                                        <tr>
                                            <td style="color: #FFFFFF">
                                                <center>
                                                    No Data Found</center>
                                            </td>
                                        </tr>
                                    </table>
                                </EmptyDataTemplate>
                            </asp:GridView>
                            <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:myconConnectionString %>"
                                ProviderName="System.Data.SqlClient" SelectCommand="mysp"
                                SelectCommandType="StoredProcedure"></asp:SqlDataSource>
                            <asp:Button ID="Button1" runat="server" Text="Button" Visible="False" />
                            <asp:LinkButton ID="LinkButton1" runat="server">Clear</asp:LinkButton>
                            <br />
                        </td>
                    </tr>
                </table>
            </ContentTemplate>
             <Triggers>
              <asp:PostBackTrigger ControlID="btnUpload" />
            </Triggers>
        </asp:UpdatePanel>
        <asp:UpdateProgress ID="UpdateProgress2" runat="server" AssociatedUpdatePanelID="UpdatePanel_1">
            <ProgressTemplate>
                <div id="progress" align="center" valign="middle" runat="server" style="border-width: thin;
                    border-color: black; position: absolute; left: 0%; top: 4%; visibility: visible;
                    vertical-align: middle; background-color: White; z-index: 40;">
                    <table width="1054px" height="510px">
                        <tr>
                            <td>
                                Please wait...<br />
                                <br />
                                <img src="image/test.gif" />
                            </td>
                        </tr>
                    </table>
                </div>
            </ProgressTemplate>
        </asp:UpdateProgress>
    </div>
</asp:Content>

Open in new window


your backend code is working fine.

once you add a trigger to your  update panel you will get the desired result without performing a full postback, it will be a partial post back and you update panel will know that this button needs an action to be done.

hope this helps.
0

Featured Post

Revamp Your Training Process

Drastically shorten your training time with WalkMe's advanced online training solution that Guides your trainees to action.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Lots of people ask this question on how to extend the “MembershipProvider” to make use of custom authentication like using existing database or make use of some other way of authentication. Many blogs show you how to extend the membership provider c…
One of the pain points with developing AJAX, JavaScript, JQuery, and other client-side behaviors is that JavaScript doesn’t allow for cross domain request for pulling content. For example, JavaScript code on www.johnchapman.name could not pull conte…
I've attached the XLSM Excel spreadsheet I used in the video and also text files containing the macros used below. https://filedb.experts-exchange.com/incoming/2017/03_w12/1151775/Permutations.txt https://filedb.experts-exchange.com/incoming/201…
This video shows how to use Hyena, from SystemTools Software, to update 100 user accounts from an external text file. View in 1080p for best video quality.

737 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question