Must declare the scalar variable error when inserting into Gridview - asp.net

Question

My webpage consist of a GridView, which allows the user to view, edit, and insert data. The data is inserted using a DetailView-Form, which opens via a javaScript-type window. One of the columns in the GridView consist of a company_guid, which is captured via a session that is setup in a log-in page. I'm attempting to capture the user's company_guid and log it into the Grid upon inserting data. I'm able to view and edit the Gridview, but I get the following error when I try to insert: Must declare the scalar variable "#companyguid".
The following is my Hypertext - GridView:
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
DataKeyNames="Part_ID" DataSourceID="SqlDataSource1"
AutoGenerateEditButton="True" AllowPaging="True" AllowSorting="True">
<Columns>
<asp:BoundField DataField="Part_ID" HeaderText="Part_ID"
SortExpression="Part_ID" InsertVisible="False" ReadOnly="True" Visible="false" />
<asp:BoundField DataField="Company_guid" HeaderText="Company_guid"
SortExpression="Company_guid" Visible="false" />
<asp:BoundField DataField="Part_Name" HeaderText="Part_Name"
SortExpression="Part_Name" />
<asp:BoundField DataField="Part_Desc" HeaderText="Part_Desc"
SortExpression="Part_Desc" />
<asp:CheckBoxField DataField="Active" HeaderText="Active"
SortExpression="Active" />
<asp:BoundField DataField="UpdateDate" HeaderText="UpdateDate"
SortExpression="UpdateDate" />
<asp:BoundField DataField="UpdateBy" HeaderText="UpdateBy"
SortExpression="UpdateBy" />
</Columns>
</asp:GridView>
The Detail View (this is what opens via the JavaScript Window):
<asp:DetailsView
id="dtlCarrier"
DataSourceID="SqlDataSource1"
AutoGenerateInsertButton="True"
AutoGenerateRows="False"
DefaultMode="Insert"
Runat="server" DataKeyNames="Part_ID">
<Fields>
<asp:BoundField DataField="Part_Name" HeaderText="Part_Name"
SortExpression="Part_Name" />
<asp:BoundField DataField="Part_Desc" HeaderText="Part_Desc"
SortExpression="Part_Desc" />
<asp:CheckBoxField
DataField="Active"
HeaderText="Active" SortExpression="Active" />
<asp:BoundField DataField="UpdateDate" HeaderText="UpdateDate"
SortExpression="UpdateDate" />
<asp:BoundField DataField="UpdateBy" HeaderText="UpdateBy"
SortExpression="UpdateBy" />
</Fields>
</asp:DetailsView>
<!-- the sql data source -->
<asp:SqlDataSource
ID="SqlDataSource1"
ConnectionString="<%$ ConnectionStrings:ShipperNotificationConnectionString %>"
SelectCommand="SELECT * FROM [Part]"
UpdateCommand="UPDATE Part SET Part_Name=#Part_Name,
Part_Desc=#Part_Desc, Active=#Active, UpdateDate=#UpdateDate, UpdateBy=#UpdateBy
WHERE Part_ID=#Part_ID"
InsertCommand="INSERT Part (company_guid,Part_Name,Part_Desc,Active,UpdateDate,UpdateBy)
VALUES (#companyguid,#Part_Name,#Part_Desc,#Active,#UpdateDate,#UpdateBy)"
runat="server"
/>
The code behind:
Public Class SupplierPartsMgmt
Inherits System.Web.UI.Page
'Globally declare my variable to hold the company_guid
Dim companyGuid As String = ""
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
'initialized companyGuid to the session varible, which is capured/stored via the log-in pg
If Not Page.IsPostBack Then
companyGuid = Session("numrecord").ToString
Else
companyGuid = Session("numrecord").ToString
End If
End Sub
Protected Sub GridView1_RowCommand(ByVal sender As Object, ByVal e As GridViewCommandEventArgs)
'Dim companyGuid As String = ""
If Not String.IsNullOrEmpty(companyGuid) Then
SqlDataSource1.InsertParameters.Add("companyguid", companyGuid)
SqlDataSource1.Insert()
End If
End Sub
End Class
Could I please get some help as to what I'm doing wrong?

Answer 1

Drop the # in this line:
SqlDataSource1.InsertParameters.Add("companyguid", companyGuid)
# is only needed while writing the query to indicate query parameters.
And if you still need the #, i think you need to declare the <InsertParameters> elements under your asp:SqlDataSource element.
Option #1
You could declare a session based insert parameter directly as follows:
<InsertParameters>
<asp:SessionParameter Name="companyguid" SessionField="companyguid" Type="String" />
</InsertParameters>
Option #2
You can also set the company guid parameter value in the oninserting command as follows:
<InsertParameters>
<asp:Parameter Name="companyguid" Type="String" />
</InsertParameters>
OnInserting="On_Inserting" - add this attribute to your SQL Data Source
protected void On_Inserting(Object sender, SqlDataSourceCommandEventArgs e)
{
e.Command.Parameters["#companyguid"].Value = valueFromSession;
}