C
CAK
Hi,
I'm having problems retaining my dynamic columns during postbacks.
I've read that if you create dynamic columns at runtime, you have to
add them during the page_init event. I've done that, but I'm not sure
what else I'm supposed to do to make this work properly. Basically,
I've created a search page with a bunch of criteria - when the user
clicks search, it searches for all the criteria that has been filled
in and eventually stores whether a criterion is active or not in a
view state variable, then it should go through them and add a column
if the criterion is active. I've been playing around with different
things, but nothing makes my dynamic columns stay when I try to sort
or, more importantly, when I try to pull data from the dynamic
columns. I've added the function to the page_init event that adds all
the dynamic columns, but am I supposed to rebind the grid afterwards?
I may also be mismanaging my view state variables.
Thanks for any ideas or suggestions anyone can give me.
Code Follows - I tried to edit it down a bit:
<asp:datagrid id="dgdSearch" runat="server" BackColor="White"
Width="374px" Font-Names="verdana"
BorderColor="#3366CC" BorderStyle="None" Font-Size="X-Small"
AutoGenerateColumns="False" AllowPaging="True" PageSize="15"
AllowSorting="True"
CellPadding="4" BorderWidth="1px">
<SelectedItemStyle Font-Bold="True" ForeColor="#CCFF99"
BackColor="#009999"></SelectedItemStyle>
<AlternatingItemStyle BackColor="Gainsboro"></AlternatingItemStyle>
<ItemStyle ForeColor="#003399" BackColor="White"></ItemStyle>
<HeaderStyle Font-Bold="True" ForeColor="#CCCCFF"
BackColor="#003399"></HeaderStyle>
<FooterStyle ForeColor="#003399" BackColor="#99CCCC"></FooterStyle>
<Columns>
<asp:HyperLinkColumn Text="View" Target="_blank"
DataNavigateUrlField="PropertyID"
DataNavigateUrlFormatString="PropertyMain.aspx?PropertyID={0}"
DataTextField="PropertyID" SortExpression="PropertyID"
HeaderText="Property ID"></asp:HyperLinkColumn>
<asp:TemplateColumn HeaderText="Mark">
<ItemTemplate>
<asp:CheckBox id="chkMark" runat="server"></asp:CheckBox>
</ItemTemplate>
</asp:TemplateColumn>
<asp:ButtonColumn Visible="False" Text="Delete"
CommandName="Delete"></asp:ButtonColumn>
</Columns>
<PagerStyle HorizontalAlign="Left" ForeColor="#003399"
BackColor="#99CCCC" Mode="NumericPages"></PagerStyle>
</asp:datagrid>
Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form
Designer
'Do not modify it using the code editor.
InitializeComponent()
Call AddDynamicColumns()
End Sub
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
'Put user code to initialize the page here
txtUser.Text = Web.HttpContext.Current.User.Identity.Name
If Not Page.IsPostBack Then
FillDropDowns()
Me.btnAddNew.Attributes.Add("onClick",
"window.open('PropertyMain.aspx');")
' Create viewstates for the boolean variables
viewstate.Add("blnCounty", False)
viewstate.Add("blnPropertyType", False)
'** additional criteria items removed for brevity ***
End If
End Sub
Private Sub btnSearch_Click(ByVal sender As System.Object, ByVal e
As System.EventArgs) Handles btnSearch.Click
FillSearchDatagrid()
End Sub
Private Sub FillSearchDatagrid()
Dim lstItem As ListItem
Dim strSql As String
Dim intCount As Integer
Dim blnCounty As Boolean
Dim blnPropertyType as Boolean
'** additional criteria items removed for brevity ***
' Reset all the variables
strSQL = " WHERE 0 = 0"
' County
intCount = 0
For Each lstItem In lstCounty.Items
If lstItem.Selected Then
If Convert.ToInt32(lstItem.Value) > 0 Then
If intCount > 0 Then
strSql += " OR County = " & lstItem.Value
Else
strSql += " AND (County = " & lstItem.Value
End If
intCount = intCount + 1
blnCounty = True
End If
End If
Next
If intCount > 0 Then
strSql += ")"
End If
' Property Type
intCount = 0
For Each lstItem In lstPropertyType.Items
If lstItem.Selected Then
If Convert.ToInt32(lstItem.Value) > 0 Then
If intCount > 0 Then
strSql += " OR PropertyType = " &
lstItem.Value
Else
strSql += " AND (PropertyType = " &
lstItem.Value
End If
intCount = intCount + 1
blnPropertyType = True
End If
End If
Next
If intCount > 0 Then
strSql += ")"
End If
'*** additional criteria items removed for brevity ***
If viewstate("SearchString") Is Nothing Then
viewstate.Add("SearchString", strSql)
Else
viewstate("SearchString") = strSql
End If
Dim dsWeb As DataSet =
DAL.Properties.PropertiesSearchDataset(strSql, _
blnCounty)
'*** additional criteria items removed for brevity ***
Dim dvWeb As New DataView(dsWeb.Tables(0))
Dim strSort As String = ""
If Not viewstate("SortField") Is Nothing Then
strSort = Convert.ToString(viewstate("SortField")) &
Convert.ToString(viewstate("SortDirection"))
Else
strSort = "PropertyID"
End If
viewstate("blnCounty") = blnCounty
viewstate("blnPropertyType") = blnPropertyType
'*** additional criteria items removed for brevity ***
dvWeb.Sort = strSort
dgdSearch.DataSource = dvWeb
dgdSearch.DataKeyField = "PropertyID"
dgdSearch.DataBind()
End Sub
Private Sub dgdSearch_SortCommand(ByVal source As Object, ByVal e
As System.Web.UI.WebControls.DataGridSortCommandEventArgs) Handles
dgdSearch.SortCommand
If dgdSearch.EditItemIndex = -1 Then
' If SortDirection viewstate doesn't exist, add it
If viewstate("SortDirection") Is Nothing Then
viewstate.Add("SortDirection", " ASC")
End If
' If SortField viewstate doesn't exist, add it
If Convert.ToString(viewstate("SortField")) Is Nothing
Then
viewstate.Add("CustomSortField", e.SortExpression)
Else
' If SortField viewstate is the same as the sort
expression, then we
' just want to change direction
If Convert.ToString(viewstate("SortField")) =
e.SortExpression Then
If Convert.ToString(viewstate("SortDirection")) =
" ASC" Then
viewstate("SortDirection") = " DESC"
Else
viewstate("SortDirection") = " ASC"
End If
Else
' SortField viewstate is different than the sort
expression, we need
' to set new sortfield
viewstate("SortField") = e.SortExpression
viewstate("SortDirection") = " ASC"
End If
End If
FillSearchDatagrid()
End If
End Sub
Private Sub dgdSearch_PageIndexChanged(ByVal source As Object,
ByVal e As System.Web.UI.WebControls.DataGridPageChangedEventArgs)
Handles dgdSearch.PageIndexChanged
If dgdSearch.EditItemIndex = -1 Then
dgdSearch.CurrentPageIndex = e.NewPageIndex
FillSearchDatagrid()
End If
End Sub
Private Sub dgdSearch_ItemDataBound(ByVal sender As Object, ByVal
e As System.Web.UI.WebControls.DataGridItemEventArgs) Handles
dgdSearch.ItemDataBound
If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType =
ListItemType.AlternatingItem Then
Dim webCtrl As WebControl
For Each webCtrl In e.Item.Controls
If CType(e.Item.Controls(2).Controls(0),
LinkButton).CommandName = "Delete" Then
CType(e.Item.Controls(2).Controls(0),
WebControl).Attributes.Add("onclick", "return confirm('Are you sure
you want to delete this item?');")
End If
Next
End If
End Sub
Private Sub dgdSearch_DeleteCommand(ByVal source As Object, ByVal
e As System.Web.UI.WebControls.DataGridCommandEventArgs) Handles
dgdSearch.DeleteCommand
DAL.Properties.PropertiesDelete(Convert.ToInt32(dgdSearch.DataKeys(e.Item.ItemIndex)))
FillSearchDatagrid()
End Sub
Private Sub chkAllowDelete_CheckedChanged(ByVal sender As Object,
ByVal e As System.EventArgs) Handles chkAllowDelete.CheckedChanged
If Me.chkAllowDelete.Checked = True Then
Me.dgdSearch.Columns(2).Visible = True
Else
Me.dgdSearch.Columns(2).Visible = False
End If
FillSearchDatagrid()
End Sub
Sub AddDynamicColumns()
Dim bndCol4 As New BoundColumn
bndCol4.HeaderText = "Property Name"
bndCol4.DataField = "PropertyName"
bndCol4.SortExpression = "PropertyName"
dgdSearch.Columns.Add(bndCol4)
If Convert.ToBoolean(viewstate("blnPropertyType")) = True Then
Dim bndCol5 As New BoundColumn
bndCol5.HeaderText = "PropertyType"
bndCol5.DataField = "DescrPropertyType"
bndCol5.SortExpression = "DescrPropertyType"
dgdSearch.Columns.Add(bndCol5)
End If
If Convert.ToBoolean(viewstate("blnCounty")) = True Then
Dim bndCol8 As New BoundColumn
bndCol8.HeaderText = "County"
bndCol8.DataField = "DescrCounty"
bndCol8.SortExpression = "DescrCounty"
dgdSearch.Columns.Add(bndCol8)
End If
'*** additional criteria items removed for brevity ***
End Sub
I'm having problems retaining my dynamic columns during postbacks.
I've read that if you create dynamic columns at runtime, you have to
add them during the page_init event. I've done that, but I'm not sure
what else I'm supposed to do to make this work properly. Basically,
I've created a search page with a bunch of criteria - when the user
clicks search, it searches for all the criteria that has been filled
in and eventually stores whether a criterion is active or not in a
view state variable, then it should go through them and add a column
if the criterion is active. I've been playing around with different
things, but nothing makes my dynamic columns stay when I try to sort
or, more importantly, when I try to pull data from the dynamic
columns. I've added the function to the page_init event that adds all
the dynamic columns, but am I supposed to rebind the grid afterwards?
I may also be mismanaging my view state variables.
Thanks for any ideas or suggestions anyone can give me.
Code Follows - I tried to edit it down a bit:
<asp:datagrid id="dgdSearch" runat="server" BackColor="White"
Width="374px" Font-Names="verdana"
BorderColor="#3366CC" BorderStyle="None" Font-Size="X-Small"
AutoGenerateColumns="False" AllowPaging="True" PageSize="15"
AllowSorting="True"
CellPadding="4" BorderWidth="1px">
<SelectedItemStyle Font-Bold="True" ForeColor="#CCFF99"
BackColor="#009999"></SelectedItemStyle>
<AlternatingItemStyle BackColor="Gainsboro"></AlternatingItemStyle>
<ItemStyle ForeColor="#003399" BackColor="White"></ItemStyle>
<HeaderStyle Font-Bold="True" ForeColor="#CCCCFF"
BackColor="#003399"></HeaderStyle>
<FooterStyle ForeColor="#003399" BackColor="#99CCCC"></FooterStyle>
<Columns>
<asp:HyperLinkColumn Text="View" Target="_blank"
DataNavigateUrlField="PropertyID"
DataNavigateUrlFormatString="PropertyMain.aspx?PropertyID={0}"
DataTextField="PropertyID" SortExpression="PropertyID"
HeaderText="Property ID"></asp:HyperLinkColumn>
<asp:TemplateColumn HeaderText="Mark">
<ItemTemplate>
<asp:CheckBox id="chkMark" runat="server"></asp:CheckBox>
</ItemTemplate>
</asp:TemplateColumn>
<asp:ButtonColumn Visible="False" Text="Delete"
CommandName="Delete"></asp:ButtonColumn>
</Columns>
<PagerStyle HorizontalAlign="Left" ForeColor="#003399"
BackColor="#99CCCC" Mode="NumericPages"></PagerStyle>
</asp:datagrid>
Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form
Designer
'Do not modify it using the code editor.
InitializeComponent()
Call AddDynamicColumns()
End Sub
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
'Put user code to initialize the page here
txtUser.Text = Web.HttpContext.Current.User.Identity.Name
If Not Page.IsPostBack Then
FillDropDowns()
Me.btnAddNew.Attributes.Add("onClick",
"window.open('PropertyMain.aspx');")
' Create viewstates for the boolean variables
viewstate.Add("blnCounty", False)
viewstate.Add("blnPropertyType", False)
'** additional criteria items removed for brevity ***
End If
End Sub
Private Sub btnSearch_Click(ByVal sender As System.Object, ByVal e
As System.EventArgs) Handles btnSearch.Click
FillSearchDatagrid()
End Sub
Private Sub FillSearchDatagrid()
Dim lstItem As ListItem
Dim strSql As String
Dim intCount As Integer
Dim blnCounty As Boolean
Dim blnPropertyType as Boolean
'** additional criteria items removed for brevity ***
' Reset all the variables
strSQL = " WHERE 0 = 0"
' County
intCount = 0
For Each lstItem In lstCounty.Items
If lstItem.Selected Then
If Convert.ToInt32(lstItem.Value) > 0 Then
If intCount > 0 Then
strSql += " OR County = " & lstItem.Value
Else
strSql += " AND (County = " & lstItem.Value
End If
intCount = intCount + 1
blnCounty = True
End If
End If
Next
If intCount > 0 Then
strSql += ")"
End If
' Property Type
intCount = 0
For Each lstItem In lstPropertyType.Items
If lstItem.Selected Then
If Convert.ToInt32(lstItem.Value) > 0 Then
If intCount > 0 Then
strSql += " OR PropertyType = " &
lstItem.Value
Else
strSql += " AND (PropertyType = " &
lstItem.Value
End If
intCount = intCount + 1
blnPropertyType = True
End If
End If
Next
If intCount > 0 Then
strSql += ")"
End If
'*** additional criteria items removed for brevity ***
If viewstate("SearchString") Is Nothing Then
viewstate.Add("SearchString", strSql)
Else
viewstate("SearchString") = strSql
End If
Dim dsWeb As DataSet =
DAL.Properties.PropertiesSearchDataset(strSql, _
blnCounty)
'*** additional criteria items removed for brevity ***
Dim dvWeb As New DataView(dsWeb.Tables(0))
Dim strSort As String = ""
If Not viewstate("SortField") Is Nothing Then
strSort = Convert.ToString(viewstate("SortField")) &
Convert.ToString(viewstate("SortDirection"))
Else
strSort = "PropertyID"
End If
viewstate("blnCounty") = blnCounty
viewstate("blnPropertyType") = blnPropertyType
'*** additional criteria items removed for brevity ***
dvWeb.Sort = strSort
dgdSearch.DataSource = dvWeb
dgdSearch.DataKeyField = "PropertyID"
dgdSearch.DataBind()
End Sub
Private Sub dgdSearch_SortCommand(ByVal source As Object, ByVal e
As System.Web.UI.WebControls.DataGridSortCommandEventArgs) Handles
dgdSearch.SortCommand
If dgdSearch.EditItemIndex = -1 Then
' If SortDirection viewstate doesn't exist, add it
If viewstate("SortDirection") Is Nothing Then
viewstate.Add("SortDirection", " ASC")
End If
' If SortField viewstate doesn't exist, add it
If Convert.ToString(viewstate("SortField")) Is Nothing
Then
viewstate.Add("CustomSortField", e.SortExpression)
Else
' If SortField viewstate is the same as the sort
expression, then we
' just want to change direction
If Convert.ToString(viewstate("SortField")) =
e.SortExpression Then
If Convert.ToString(viewstate("SortDirection")) =
" ASC" Then
viewstate("SortDirection") = " DESC"
Else
viewstate("SortDirection") = " ASC"
End If
Else
' SortField viewstate is different than the sort
expression, we need
' to set new sortfield
viewstate("SortField") = e.SortExpression
viewstate("SortDirection") = " ASC"
End If
End If
FillSearchDatagrid()
End If
End Sub
Private Sub dgdSearch_PageIndexChanged(ByVal source As Object,
ByVal e As System.Web.UI.WebControls.DataGridPageChangedEventArgs)
Handles dgdSearch.PageIndexChanged
If dgdSearch.EditItemIndex = -1 Then
dgdSearch.CurrentPageIndex = e.NewPageIndex
FillSearchDatagrid()
End If
End Sub
Private Sub dgdSearch_ItemDataBound(ByVal sender As Object, ByVal
e As System.Web.UI.WebControls.DataGridItemEventArgs) Handles
dgdSearch.ItemDataBound
If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType =
ListItemType.AlternatingItem Then
Dim webCtrl As WebControl
For Each webCtrl In e.Item.Controls
If CType(e.Item.Controls(2).Controls(0),
LinkButton).CommandName = "Delete" Then
CType(e.Item.Controls(2).Controls(0),
WebControl).Attributes.Add("onclick", "return confirm('Are you sure
you want to delete this item?');")
End If
Next
End If
End Sub
Private Sub dgdSearch_DeleteCommand(ByVal source As Object, ByVal
e As System.Web.UI.WebControls.DataGridCommandEventArgs) Handles
dgdSearch.DeleteCommand
DAL.Properties.PropertiesDelete(Convert.ToInt32(dgdSearch.DataKeys(e.Item.ItemIndex)))
FillSearchDatagrid()
End Sub
Private Sub chkAllowDelete_CheckedChanged(ByVal sender As Object,
ByVal e As System.EventArgs) Handles chkAllowDelete.CheckedChanged
If Me.chkAllowDelete.Checked = True Then
Me.dgdSearch.Columns(2).Visible = True
Else
Me.dgdSearch.Columns(2).Visible = False
End If
FillSearchDatagrid()
End Sub
Sub AddDynamicColumns()
Dim bndCol4 As New BoundColumn
bndCol4.HeaderText = "Property Name"
bndCol4.DataField = "PropertyName"
bndCol4.SortExpression = "PropertyName"
dgdSearch.Columns.Add(bndCol4)
If Convert.ToBoolean(viewstate("blnPropertyType")) = True Then
Dim bndCol5 As New BoundColumn
bndCol5.HeaderText = "PropertyType"
bndCol5.DataField = "DescrPropertyType"
bndCol5.SortExpression = "DescrPropertyType"
dgdSearch.Columns.Add(bndCol5)
End If
If Convert.ToBoolean(viewstate("blnCounty")) = True Then
Dim bndCol8 As New BoundColumn
bndCol8.HeaderText = "County"
bndCol8.DataField = "DescrCounty"
bndCol8.SortExpression = "DescrCounty"
dgdSearch.Columns.Add(bndCol8)
End If
'*** additional criteria items removed for brevity ***
End Sub