I am trying to change the datasource of a GridView and then show the rows. It works perfectly when the Grid is loaded the first time, however when I do something to change the datasource, I get a "object reference not set to an instance of an object" error.I still get the grid to update either way, just when I select a row (to view a document), I get the error unless the Grid is first loaded.Here is the Grid Definition & SqlDataSource Definition in the aspx file:
Here is the CodeBehind:
I have tried several things with no success.
Code:
<body>
<form id="form1" runat="server">
<table cellpadding="0" cellspacing="0" width="100%">
<% Try%>
<!--#include file ="header.inc"-->
<% Catch ex As Exception
Me.lblMessage.Text = "Authentication Error. Please logoff and back on."
End Try
%>
</table>
<asp:Label ID="Label2" runat="server"></asp:Label>
<table width="100%">
<tr>
<td align="center" colspan="4">
<asp:Label ID="Label1" runat="server" SkinID="title" Text="All Documents"></asp:Label></td>
</tr>
<tr>
<td class="style1">
</td>
<td colspan="3">
</td>
</tr>
<tr>
<td class="style1">Filter By:</td>
<td class="style2">
<asp:DropDownList ID="FilterDropDown" runat="server" Height="20px" Width="222px" AutoPostBack="True" OnSelectedIndexChanged="FilterDropDown_SelectedIndexChanged">
<asp:ListItem Value="ALL">ALL</asp:ListItem>
<asp:ListItem Value="Check Request">Check Request</asp:ListItem>
<asp:ListItem Value="Invoice">Invoice</asp:ListItem>
<asp:ListItem Value="W9">W9</asp:ListItem>
<asp:ListItem Value="Receipt">Receipt</asp:ListItem>
<asp:ListItem Value="Budget">Budget</asp:ListItem>
<asp:ListItem Value="Consent">Consent Form</asp:ListItem>
<asp:ListItem Value="HIPAA">HIPAA</asp:ListItem>
</asp:DropDownList>
</td>
<td class="style3">
<asp:TextBox ID="SearchTextBox" runat="server" Width="327px"></asp:TextBox>
</td>
<td>
<asp:Button ID="SearchButton" runat="server" Text="Search" Width="80px" />
</td>
</tr>
</table>
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="fileNewName"
DataSourceID="SqlDataSource_Filter" AllowSorting="True" Width="100%">
<Columns>
<asp:CommandField ShowSelectButton="True" />
<asp:BoundField DataField="fileOldName" HeaderText="File Name" SortExpression="fileOldName" />
<asp:BoundField DataField="fileDescription" HeaderText="Description" SortExpression="fileDescription" />
<asp:BoundField DataField="createDate" HeaderText="Upload Date" SortExpression="createDate" />
<asp:BoundField DataField="id" HeaderText="id" InsertVisible="False" SortExpression="id" Visible="true" />
</Columns>
</asp:GridView>
<asp:SqlDataSource ID="SqlDataSource_Filter" runat="server" ConnectionString="<%$ ConnectionStrings:ClinicalTrialsConnectionString %>"
SelectCommand="sp_getDocumentList_Filtered" SelectCommandType="StoredProcedure">
<SelectParameters>
<asp:Parameter Name="FilterBy" Type="String" DefaultValue="All" />
</SelectParameters>
</asp:SqlDataSource>
<asp:SqlDataSource ID="SqlDataSource_Search" runat="server" ConnectionString="<%$ ConnectionStrings:ClinicalTrialsConnectionString %>"
SelectCommand="sp_getDocumentList_Search" SelectCommandType="StoredProcedure">
<SelectParameters>
<asp:Parameter Name="SearchCriteria" Type="String" DefaultValue="All" />
</SelectParameters>
</asp:SqlDataSource>
<asp:Label ID="lblMessage" runat="server" SkinID="error" Text=""></asp:Label><br />
<br />
<!--#include file ="footer.inc"-->
</form>
</body>Here is the CodeBehind:
Code:
Partial Public Class viewDocuments
Inherits System.Web.UI.Page
Private Sub SqlDataSource_Filter_Selecting(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.SqlDataSourceSelectingEventArgs) Handles SqlDataSource_Filter.Selecting
End Sub
Protected Sub SqlDataSource_Search_Selecting(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.SqlDataSourceSelectingEventArgs) Handles SqlDataSource_Search.Selecting
End Sub
Protected Sub GridView1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles GridView1.SelectedIndexChanged
Dim localFileName As String = ""
Dim originalFilename As String
Dim userId As String
Dim userPw As String
Dim userDomain As String
Try
GridView1.DataBind()
localFileName = My.Settings.DocumentPath.ToString + Me.GridView1.SelectedDataKey.Value.ToString
originalFilename = Me.GridView1.SelectedRow.Cells(1).Text
userId = My.Settings.DocumentUserId.ToString
userPw = My.Settings.DocumentUserPw.ToString
userDomain = My.Settings.DocumentUserDomain.ToString
Dim Impersonate As New Impersonation.Impersonate 'Instantiate the class into a variable
Dim User As System.Security.Principal.WindowsImpersonationContext
User = Impersonate.ImpersonateUser(userId, userPw, userDomain) 'Start the Impersonation
Dim liveStream As New System.IO.FileStream(localFileName, System.IO.FileMode.Open, System.IO.FileAccess.Read)
Dim buffer As Byte() = New Byte(CInt(liveStream.Length) - 1) {}
liveStream.Read(buffer, 0, CInt(liveStream.Length))
liveStream.Close()
Response.Clear()
Response.ContentType = "application/octet-stream"
Response.AddHeader("Content-Length", buffer.Length.ToString())
Response.AddHeader("Content-Disposition", "attachment; filename=" + originalFilename)
Response.BinaryWrite(buffer)
Response.End()
Impersonate.UndoImpersonate(User) 'Kill the Impersonation
Catch etax As Threading.ThreadAbortException
' Do Nothing
Catch ex As Exception
Try
Me.lblMessage.Text = "Error " + ex.Message
Dim dataAccess As New DAO
Dim parameters As String = "accountId " + Request.QueryString("accountId") + " localFileName " + localFileName
dataAccess.insertErrorLog(parameters, "Document Centert GridView1_SelectedIndexChanged", ex.Message, ex.ToString, Server.UrlDecode(Request.Cookies("authenticated")("user").ToString), Context.Request.UserHostAddress.ToString)
Catch ex1 As Exception
Response.Write("ERROR: " + ex1.ToString)
End Try
End Try
End Sub
Protected Sub FilterDropDown_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs) Handles FilterDropDown.SelectedIndexChanged
Dim FilterValue As String
FilterValue = FilterDropDown.SelectedItem.Value
With SqlDataSource_Filter
.SelectParameters("FilterBy").DefaultValue = FilterValue
.SelectCommand = "sp_getDocumentList_Filtered"
'.DataBind()
End With
With GridView1
.DataSourceID = Nothing
.DataSource = SqlDataSource_Filter
.DataBind()
.SelectedIndex = -1
End With
End Sub
Protected Sub SearchButton_Click(ByVal sender As Object, ByVal e As EventArgs) Handles SearchButton.Click
Dim Criteria As String
Criteria = SearchTextBox.Text
With SqlDataSource_Search
.SelectCommand = "sp_getDocumentList_Search"
.SelectParameters("SearchCriteria").DefaultValue = Criteria
'.DataBind()
End With
With GridView1
.DataSourceID = Nothing
.DataSource = SqlDataSource_Search
.DataBind()
.SelectedIndex = -1
End With
End Sub
Private Sub form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles form1.Load
' Have to set visibility to true until after data is bound due to GridViews
' inability to get value of hidden column cells
With GridView1
.Columns(4).Visible = True
.DataBind()
.Columns(4).Visible = False
End With
Dim mid As String = ""
Try
mid = Server.UrlDecode(Request.Cookies("authenticated")("user").ToString)
Catch ex As Exception
Response.Redirect("login.asp", False)
End Try
End Sub
Protected Sub GridView1_PageIndexChanging(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewPageEventArgs) Handles GridView1.PageIndexChanging
GridView1.PageIndex = e.NewPageIndex
GridView1.DataBind()
End Sub
End ClassI have tried several things with no success.