Selecting items in a grid using checkboxes and getting a list of items selected...

[Wokawidget]

I have a dataset with the following fields in a table.

DocketNumber, Status, Description

I also bring back contractor info, but that irrelevant for this as it's only for display purposes

These are displayed in a datagrid.

I also have a 3rd column which is a checkbox

What I want to do is select x many items from the grid by ticking the checkbox, and then get an array of DocketNumers that have been selected.

Is this possible?

Attached is the exact screen shot of my grid.

Woka

[dj4uk]

I would have thought the best way to do it is set the DocketNumber as a DataKey on the DataGrid so it is easily accessible.

Then you need a method that loops through each item in the DataGrid i.e. DataGrid.Items.

For each item you could load the checkbox into a local variable (where dgrdName is the ID of the DataGrid and checkboxID is the CheckBox ID):

	CheckBox chkBox = (CheckBox) dgrdName.Items[itemNum].FindControl("checkboxID");

You can then use this local variable to test if it is checked or not and then add the Docket Number into an ArrayList if needed:

	ArrayList DocketNumbers = new ArrayList();

	if (chkBox.Checked) {
		DocketNumbers.Add(dgrdName.DataKeys[itemNum]);
	}

Note: itemNum is the item index as iterated by a for loop (to loop through all the datagrid items).

Hope that makes sense.

DJ

[Wokawidget]

Fantastic

Cheers.

However, when I click a button, and try to loop the datagrid seems to have 0 DataGridItems

I thought the ViewState was supposed to reconstruct the grid...am I missing something?

Woka

[dj4uk]

It could be a databinding problem i.e. when the page posts back it is rebinding the data every time and you are trying to access the items when it has been cleared out. You really only want to call DataGrid.DataBind() when it isn't a postback or after you have updated some information and you want it to be show on screen.

Check that first let me know if it is still returning 0.

DJ

[Wokawidget]

Hmmm...I did have SetupGrid in the Page_load event.

	Private Sub SetGridProperties()
		With grdDockets
			.AutoGenerateColumns = False
			.AllowPaging = False
			.AllowSorting = False
			.PagerStyle.Mode = PagerMode.NextPrev
			.PagerStyle.NextPageText = "Next"
			.PagerStyle.PrevPageText = "Prev"
			.PageSize = 10
		End With
	End Sub

However, I have now moved this into my BindDockets function that does only get called once.
So, when I have a postback, no grid props are being changed etc. However, it still says I have 0 rows
Ahhhh...not sure if this is a major issue, but my grid is in a user web control...this shouldn't make a difference should it? I bet it does

Woka

[dj4uk]

Can you chuck up a bit more code - attach a file or something?

DJ

[Wokawidget]

OK. My usercontrol code is:

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

	End Sub

	Public Sub BindDockets(ByRef Dockets As GateKeeperElevator.Dockets, ByVal AllowSelect As Boolean)
		SetGridProperties()
		CreateColumns(AllowSelect)
		grdDockets.DataSource = Dockets
		grdDockets.DataBind()
	End Sub

	Private Sub CreateColumns(ByVal AllowSelect As Boolean)
		Dim tc As TemplateColumn

		grdDockets.Columns.Clear()
		tc = New TemplateColumn
		tc.HeaderTemplate = New DocketTemplate(ListItemType.Header, "Docket")
		tc.ItemTemplate = New DocketTemplate(ListItemType.Item, "DocketNo")
		grdDockets.Columns.Add(tc)
		tc = New TemplateColumn
		tc.HeaderTemplate = New ContractorTemplate(ListItemType.Header, "Contractor")
		tc.ItemTemplate = New ContractorTemplate(ListItemType.Item, "Contractor")
		grdDockets.Columns.Add(tc)
		If AllowSelect Then
			tc = New TemplateColumn
			tc.HeaderTemplate = New SelectTemplate(ListItemType.Header, "")
			tc.ItemTemplate = New SelectTemplate(ListItemType.Item, "")
			grdDockets.Columns.Add(tc)
		End If
	End Sub

	Private Sub SetGridProperties()
		With grdDockets
			.AutoGenerateColumns = False
			.AllowPaging = False
			.AllowSorting = False
			.PagerStyle.Mode = PagerMode.NextPrev
			.PagerStyle.NextPageText = "Next"
			.PagerStyle.PrevPageText = "Prev"
			.PageSize = 10
		End With
	End Sub

	Public Function GetSelectedDocketNos() As String()
		Dim DataItem As DataGridItem
		Dim chk As CheckBox
		Dim Dockets() As String
		For Each DataItem In grdDockets.Items
			chk = CType(DataItem.FindControl("chkSelected"), System.Web.UI.WebControls.CheckBox)
			If chk.Checked Then
				'change Dockets array
				Dockets(Dockets.Length - 1) = CType(DataItem.FindControl("lblDocketNo"), System.Web.UI.WebControls.Label).Text
			End If
		Next
		Return Dockets
	End Function
End Class

I use template items to create the funky cell structures you see in the grid.
Here's the Template to Display the docket.

Public Class DocketTemplate
	Implements ITemplate

	Private TemplateType As ListItemType
	Private ColumnHeading As String

	Public Sub New(ByVal Type As ListItemType, ByVal Heading As String)
		TemplateType = Type
		ColumnHeading = Heading
	End Sub

	Public Sub InstantiateIn(ByVal container As Control) Implements ITemplate.InstantiateIn
		Select Case TemplateType
			Case ListItemType.Header
				Dim lbl As New Label
				lbl.Text = ColumnHeading
				container.Controls.Add(lbl)
			Case ListItemType.Item
				Dim tbl As New Table
				Dim Row As TableRow
				Dim Cell As TableCell
				Dim lbl As Label
				Row = New TableRow
				Cell = New TableCell
				lbl = New Label
				lbl.ID = "lblDocketNo"
				lbl.Font.Size = New FontUnit(8)
				lbl.Font.Bold = True
				Cell.Controls.Add(lbl)
				AddHandler lbl.DataBinding, AddressOf DocketNo_DataBinding
				Row.Cells.Add(Cell)
				tbl.Rows.Add(Row)

				Row = New TableRow
				Cell = New TableCell
				lbl = New Label
				lbl.Font.Size = New FontUnit(7)
				lbl.ForeColor = Color.Gray
				Cell.Controls.Add(lbl)
				AddHandler lbl.DataBinding, AddressOf Status_DataBinding
				Row.Cells.Add(Cell)
				tbl.Rows.Add(Row)

				Row = New TableRow
				Cell = New TableCell
				lbl = New Label
				lbl.Font.Size = New FontUnit(7)
				lbl.ForeColor = Color.Gray
				Cell.Controls.Add(lbl)
				AddHandler lbl.DataBinding, AddressOf Description_DataBinding
				Row.Cells.Add(Cell)
				tbl.Rows.Add(Row)

				container.Controls.Add(tbl)
				Cell = CType(container, TableCell)
				Cell.VerticalAlign = VerticalAlign.Top
		End Select
	End Sub

	Private Sub DocketNo_DataBinding(ByVal sender As Object, ByVal e As System.EventArgs)
		Dim lbl As Label
		lbl = CType(sender, Label)
		Dim container As DataGridItem
		container = CType(lbl.NamingContainer, DataGridItem)
		lbl.Text = CType(DataBinder.Eval(container.DataItem, "DocketNo"), String)
		'lnk.NavigateUrl = "Docket.aspx?Key=" & CType(DataBinder.Eval(container.DataItem, "DocketNo"), String)
	End Sub

	Private Sub Description_DataBinding(ByVal sender As Object, ByVal e As System.EventArgs)
		Dim lbl As Label
		lbl = CType(sender, Label)
		Dim container As DataGridItem
		container = CType(lbl.NamingContainer, DataGridItem)
		lbl.Text = CType(DataBinder.Eval(container.DataItem, "Description"), String)
	End Sub

	Private Sub Status_DataBinding(ByVal sender As Object, ByVal e As System.EventArgs)
		Dim lbl As Label
		lbl = CType(sender, Label)
		Dim container As DataGridItem
		container = CType(lbl.NamingContainer, DataGridItem)
		lbl.Text = (New GateKeeperBR.DocketsBR).GetStatusDescription(CType(DataBinder.Eval(container.DataItem, "Status"), GateKeeperBR.DocketsBR.vbDocketStatusConstants))
	End Sub

	Private Sub ContractorName_DataBinding(ByVal sender As Object, ByVal e As System.EventArgs)
		Dim lbl As Label
		lbl = CType(sender, Label)
		Dim container As DataGridItem
		container = CType(lbl.NamingContainer, DataGridItem)
		lbl.Text = CType(DataBinder.Eval(container.DataItem, "ContractorName"), String)
	End Sub
End Class

Does that help.
I know it may be a little evil.

Any pointers would be most welcome.

Woof

[dj4uk]

I'll have a read in the morning and get back to you.

DJ

[Wokawidget]

Thank you very much you your time and help. Much appreciated.

Woka

[dj4uk]

Just done a quick pass on the code - VB.NET ain't my primary language so its slowing me down a tad.

First thing in GetSelectedDocketNos() you declare the Dockets Array and then use:

Dockets(Dockets.Length - 1) = CType(DataItem.FindControl("lblDocketNo"), System.Web.UI.WebControls.Label).Text

Surely as the inital length of the Array is 0 and you are on the first iteration uning 0 - 1 or in other words an array index of -1.

Does that help at all?

DJ

[Wokawidget]

No...that code doesn't get executed. I know there was an err with that code.
I have create a new project, with a new user control, with a new data grid...etc and this works.

Apparently its because I am dynamically adding columns
This sucks

Woka

[dj4uk]

It shouldn't matter that you are dynamically adding columns the only problem is at what point you are adding them in comparison to when you are trying to access the cell contents.

Could you post the complete code for the page and the user control (including HTML part) as I'm having real trouble linking everything together in my head.

Cheers

DJ