Trying to build dropdownlist during datagrid Edit Command

[lanm]

When I run this code I get:
Object reference not set to an instance of an object.

It's referring to the line of:
ddlTitle1.DataSource = DS

Here's the code:

Private Sub DataGrid1_EditCommand(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataGridCommandEventArgs) Handles DataGrid1.EditCommand
DataGrid1.EditItemIndex = e.Item.ItemIndex
'Build the DDL For the Title section
Con1.Open()
Dim strDDL As String
strDDL = "SELECT DISTINCT Title FROM Employees ORDER BY Title"
Dim da As New OleDb.OleDbDataAdapter()
da.SelectCommand = New OleDb.OleDbCommand(strDDL, Con1)
Dim DS As New DataSet()
da.Fill(DS)
Dim ddlTitle1 As DropDownList = e.Item.FindControl("ddlTitle")

ddlTitle1.DataSource = DS
ddlTitle1.DataMember = "Employees"
ddlTitle1.DataTextField = "Title"
ddlTitle1.DataValueField = "Title"
ddlTitle1.DataBind()
Con1.Close()

 

[markdmac]

Don't know if you can use this but here is what I use in my datagrid:

<asp:DropDownList id="dropTypeAdd" runat="server">
        <asp:ListItem Selected="True">Band Night</asp:ListItem>
        <asp:ListItem>Fundraiser</asp:ListItem>
    </asp:DropDownList>

If I am thinking too "simple" my apologies. I'm new to ASP.Net and just learning my way around it.



I hope you find this post helpful.

Regards,

Mark

 

[lanm]

markdmac,

thanks, but what you've listed is for static data. Mine will need to be dynamic.

I just want to be able to build the dataadapter and Dataset by hand in the Edit_Command handler

 

[markdmac]

Sorry I wasn't any help.

 

[dvannoy]

This is how I do it.

Dim rs As New SqlCommand("SELECT Records FROM Table ", cn)

cn.Open()

cboBox.DataSource = rs.ExecuteReader
cboBox.DataTextField = "FieldName"
cboBox.DataValueField = "FieldName"
cboBox.DataBind()

cn.Close()

 

[jbenson001]

It could be that your FindControl is not finding the control. Step through the code and see if ddlTitle1 is NOTHING after the FindControl line.

 

[jbenson001]

Actually I belive you need to change that line and include a referenc to the cell you want to find the control in:

Dim ddlTitle1 As DropDownList = e.Item.[b]Cells(cell index)[/b].FindControl("ddlTitle")

 

[cjburkha]

Also, you might have to do it in another event handler:

OnItemCreated(ByVal e As DataGridItemEventArgs)
        MyBase.OnItemCreated(e)
        Dim i As Integer
        Select Case e.Item.ItemType
            Case ListItemType.EditItem

The datagrid might not have created the edititem control at the time it is handling onEdit. Not sure since I am still getting a hold of when all these events fire, and the order myself.

But I have sucess with this code, although I am adding the DL myself:

Sub OnItemCreated(ByVal e As DataGridItemEventArgs)
        MyBase.OnItemCreated(e)
        Dim i As Integer
        Select Case e.Item.ItemType
            Case ListItemType.EditItem
                Dim eventDL As DropDownList = New DropDownList()
                eventDL.DataSource = sqlSelect("Select * from [event]")
                eventDL.DataTextField = "eventName"
                eventDL.DataValueField = "pk_Event"
                eventDL.DataBind()
                e.Item.Cells(3).Controls.Add(eventDL)

 

[lanm]

If I use the following code, it looks as if the dropdownlist is nothing. My label3.Text is getting populated with "The dropdownlist is not found". I know it should be cells(3), and the id is in fact ddlTitle.
Here's the code:

DataGrid1.EditItemIndex = e.Item.ItemIndex
Dim ddlTitle1 As DropDownList = e.Item.Cells(3).FindControl("ddlTitle")
Con1.Open()
Dim strDDL As String
strDDL = "SELECT DISTINCT Title FROM Employees ORDER BY Title"
Dim da As New OleDb.OleDbDataAdapter()
da.SelectCommand = New OleDb.OleDbCommand(strDDL, Con1)
Dim DS As New DataSet()
da.Fill(DS)
If ddlTitle1 Is Nothing Then
Label3.Text = "The dropdownlist is not found"
Else
ddlTitle1.DataSource = DS
ddlTitle1.DataMember = "Employees"
ddlTitle1.DataTextField = "Title"
ddlTitle1.DataValueField = "Title"
ddlTitle1.DataBind()
Con1.Close()
End If

 

[lanm]

cjburkha,

What Imports are you using?
I've got:
Imports System.Web.UI.Page

If I use the code:
Private Sub DataGrid1_ItemCreated(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.DataGridItemEventArgs) Handles DataGrid1.ItemCreated
MyBase.OnItemCreated(e)
MyBase.Oni()
Dim i As Integer
Select Case e.Item.ItemType
Case ListItemType.EditItem
Dim ddlName As DropDownList = New DropDownList()
Con1.Open()
Dim strDDL As String
strDDL = "SELECT DISTINCT Title FROM Employees ORDER BY Title"
Dim da As New OleDb.OleDbDataAdapter()
da.SelectCommand = New OleDb.OleDbCommand(strDDL, Con1)
Dim DS As New DataSet()
da.Fill(DS)
ddlName.DataSource = DS
ddlName.DataTextField = "Title"
ddlName.DataValueField = "Title"
ddlName.DataBind()
e.Item.Cells(3).Controls.Add(ddlName)
End Select
End Sub

...the first two lines of code:
MyBase.OnItemCreated(e)
MyBase.Oni()

...say they're not members of "System.Web.UI.Page"

Any ideas?

Thanks!

 

[lanm]

sorry....MyBase.Oni() is a typo..I deleted this line.

 

[lanm]

Just tried this too, and ....

MyBase.OnItemCreated(e)

.....isn't a member of System.Web.UI.Page


Sub OnItemCreated(ByVal e As DataGridItemEventArgs)
MyBase.OnItemCreated(e)
Dim i As Integer
Select Case e.Item.ItemType
Case ListItemType.EditItem
Dim ddlName As DropDownList = New DropDownList()
Con1.Open()
Dim strDDL As String
strDDL = "SELECT DISTINCT Title FROM Employees ORDER BY Title"
Dim da As New OleDb.OleDbDataAdapter()
da.SelectCommand = New OleDb.OleDbCommand(strDDL, Con1)
Dim DS As New DataSet()
da.Fill(DS)
ddlName.DataSource = DS
ddlName.DataTextField = "Title"
ddlName.DataValueField = "Title"
ddlName.DataBind()
e.Item.Cells(3).Controls.Add(ddlName)
End Select
End Sub

 

[lanm]

Okay...duh...it should be Me.OnItemCreated(e), but there's still no ddl created when the Edit link is clicked. Do I need to call something in the Datagrid's EditCommand handler?

Thanks for the help!

 

[cjburkha]

I think your onItemCreated is not being called. Did you wire it in your asp code like

<asp:datagrid onitemcreated = "myitemcreated">

I know thats not what I gave you at first, sorry, I'm doing it a bit different and forgot to take that into account.

 

[lanm]

cjburkha,

Here's the code-behind:
Sub MyItemCreated(ByVal e As DataGridItemEventArgs)
Me.MyItemCreated(e)
Dim i As Integer
Select Case e.Item.ItemType
Case ListItemType.EditItem
sCon1.Open()
Dim strDDL As String
strDDL = "SELECT Signature_Authority_Names.Authority+' | '+Signature_Authority_Names.ZNumber AS Expr1, "
strDDL &= "Signature_Authority_Names.Authority FROM Signature_Authority_Names Order by Expr1"
Dim cmd As New SqlCommand(strDDL, sCon1)
Dim da As New SqlDataAdapter
da.SelectCommand = cmd
Dim DS As New DataSet
da.Fill(DS)
Dim ddlName As DropDownList = e.Item.Cells(1).FindControl("ddlName")
ddlName.DataSource = DS
ddlName.DataMember = "Signature_Authority_Names"
ddlName.DataTextField = "Expr1"
ddlName.DataValueField = "Authority"
ddlName.DataBind()
sCon1.Close()
End Select

Here's the HTML:
<asp:datagrid id="DataGrid1" OnItemCreated="MyItemCreated"

When I run the code, I get:
Compiler Error Message: BC30408: Method 'Public Sub MyItemCreated(e As System.Web.UI.WebControls.DataGridItemEventArgs)' does not have the same signature as delegate 'Delegate Sub DataGridItemEventHandler(sender As Object, e As System.Web.UI.WebControls.DataGridItemEventArgs)'.

It looks like MyItemCreated needs a sender parameter too.
If I do this:
Sub MyItemCreated(ByVal Sender As Object, ByVal e As DataGridItemEventArgs)
Me.MyItemCreated(Sender, e)

..it hangs for minutes, then I just kill the app.

 

[markdmac]

As luck would have it, I too need to now create a dynamic drop down list but my needs are a little different here. I just need to create a list of dates starting from this year and going out an additional 10 years. Here is what I have but I just get a blank drop down.

Function BuildYears()
		Dim ThisYear As Integer
		Dim X As Integer
		Dim opString As String
		ThisYear = CINT(Year(Date))
		For X = 0 to 10
			opString = opString & "<option label='" & (ThisYear + X) & "' value='" & (ThisYear + X) &"' \>"
		Next
		BuildYears = opString
	End Function




<select id=\"expYear\" name=\"expYear\" style=\"width:60px;\" size=\"1\">"
<script>
'GENERATE A YEAR DROP-DOWN 10 YEARS OUT FROM THIS YEAR:
BuildYears()
</script>
</select>

If I pop my function into a vbscript file it gives me the results I am looking for, so what am I doing wrong here?

I hope you find this post helpful.

Regards,

Mark