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

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

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):

Code:

---

        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:

Code:

---

        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

Fantastic :D

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

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

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

Code:

---

        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

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

DJ

OK. My usercontrol code is:

Code:

---

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.

Code:

---

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

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

DJ

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

Woka

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:

Code:

---

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

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

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