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Hi
I'm creating checkbox list dynamically and populate it with database values.As I want this list to be shown on first time i created it in if-else block of "Not page.ispostback". Now I want to get the values of checkboxes which user selected on post back. but when i try to get the values on post back, it gives me an error like "checkbox list doesnot exist" or "Object reference not set".Please help me  . Following is my code:
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
if Not page.ispostback
Dim Reader As SqlDataReader
Dim uamenity_Chklist As CheckBoxList = New CheckBoxList
sqlStatement = "SELECT unitamenity_id,unitAmenity_name FROM UNITAMENITY_MASTER"
cmd.CommandText = sqlStatement
cmd.Connection = conn
Reader = cmd.ExecuteReader()
uamenity_Chklist.ID = "chkUamenity"
uamenity_Chklist.DataSource = Reader
uamenity_Chklist.RepeatColumns = 2
uamenity_Chklist.DataValueField = "unitamenity_id"
uamenity_Chklist.DataTextField = "unitAmenity_name"
uamenity_Chklist.DataBind()
Reader.Close()
Dim CBrow As New HtmlTableRow
UAmenity.Rows.Add(CBrow)
Dim CBCell As New HtmlTableCell
CBrow.Cells.Add(CBCell)
CBCell.Controls.Add(uamenity_Chklist)
end if
end sub
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You can try setting the enable viewstate to true; but I think the checkBox list will be gone by the time you get to the onclick event. Because the HTMLTable will be loaded into memory without the checkboxlist. Check the page init event to see if you can access the values of the checkbox then.
how vital enterprise application are for proactive organizations leveraging collective synergy to think outside the box and formulate their key objectives into a win-win game plan with a quality-driven approach that focuses on empowering key players to drive-up their core competencies and increase expectations with an all-around initiative to drive up the bottom-line. But of course, that's all a "high level" overview of things
--thedailywtf 3/21/06
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The thing is that the postback resets the page to it's original state, so any information regarding the dynamically created controls is lost. Why is that? Because the Page class is stateless. The Page recreates child controls based on the tags in the aspx files, so your controls not being present there are not shown. What you need to do is recreate the controls in the OnInit event or any event that fires before PageLoad, or in PageLoad if you do a check to see is the page is posted back. See this article[^] as an example.
regards,
Mircea
Many people spend their life going to sleep when they’re not sleepy and waking up while they still are.
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Nice post, great article. I was trying to explain that but couldn't.
how vital enterprise application are for proactive organizations leveraging collective synergy to think outside the box and formulate their key objectives into a win-win game plan with a quality-driven approach that focuses on empowering key players to drive-up their core competencies and increase expectations with an all-around initiative to drive up the bottom-line. But of course, that's all a "high level" overview of things
--thedailywtf 3/21/06
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Thanks. That's why we're here 
regards,
Mircea
Many people spend their life going to sleep when they’re not sleepy and waking up while they still are.
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Hi, I've created a standard GridView with an sqlDataSource, I've enabled update and delete and created the updateQuery and the DeleteQuery in the sqldatasource.
I tried it and it worked.
Then I tried to add a filter modifing the Sqldatasource proprieties in the Design:
FilterExpression = {0}
FilterParameters = {newpar,Request.Form("hdd_where")}
//hdd_where is an html hidden input
The select worked and showed me only the correct rows,but when I tried to delete or update a row nothing happened,and no error message was thrown.
I've observed that if you set the propriety ConflictDetection to CompareAllValues an error message is thrown:
"You have specified that your update command compares all values on SqlDataSource 'MySqlDataSource', but the dictionary passed in for oldValues is empty. Pass in a valid dictionary for update or change your mode to OverwriteChanges"
Now if the oldValues dictionary is empty every sql command that uses @original_KeyName parameter doesn't work.
ex:
"DELETE FROM [t_plro] WHERE [plro_ID] = @original_plro_ID" If @original_plro_ID doesn't exist no rows are deleted
the same goes for the update.
What I would like to know is : Why the oldValues Dictionary is empty if you specify a filterParameter? Is there a way to solve this situation?
Thank you for your help
Francy
p.s. I've also tried to modify on the fly the
sqlDataSource.SelectQuery but on the postback the sqldatasource execute the delete/update on the wrong row,because it uses the SelectQuery saved in the aspx file
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I suggesting using stored procs for your select and update, that will make it easier. For the select query, here is a trick for you.
In the where clause write [plro_ID] = isnull(@original_plro_ID, [plro_ID]) and set the default of the paramter = null in the create proc statement. Then if you have a filter add the parameter if not don't.
how vital enterprise application are for proactive organizations leveraging collective synergy to think outside the box and formulate their key objectives into a win-win game plan with a quality-driven approach that focuses on empowering key players to drive-up their core competencies and increase expectations with an all-around initiative to drive up the bottom-line. But of course, that's all a "high level" overview of things
--thedailywtf 3/21/06
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Thank's for your answer.
I don't understand how the trick should work.
I modified the select query in this way:
"SELECT * FROM [t_plro_PriceListRoundings] WHERE [plro_ListName]=isnull(@ListName, [plro_ListName])"
ListName = Request.Form("hdd_Where")
ConvertEmptyStringToNull = True;
DefaultValue = null (I've tried leaving this propriety blank)
Direction = input
FormField = hdd_Where
Name = ListName
Size = 0
Type = String
When I load the page the gridview isn't there .If I open the page in html mode , the Gridview doesn't exist.
Could you tell me what I did wrong?
Thank you
Francy
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Could you post your code snippets ? I believe that you can use the FilterExpression with the SqlDataSource control and the update command can execute properly.
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Sorry but what code snipplets are you talking about?
I didn't write any code, I only modified the sqlDataSource proprieties:
Select query: "SELECT * FROM [t_plro_PriceListRoundings]"
Delete query: "DELETE FROM [t_plro_PriceListRoundings] WHERE [plro_ID] = @original_plro_ID"
Update query: "UPDATE [t_plro_PriceListRoundings] SET [plro_PriceMinValue] = @plro_PriceMinValue, [plro_PriceMaxValue] = @plro_PriceMaxValue, [plro_RoundingValue] = @plro_RoundingValue, [plro_ListName] = @plro_ListName, [plro_FixedAmmount] = @plro_FixedAmmount WHERE [plro_ID] = @original_plro_ID"
Filter expression: "{0}"
Filter parameters: "{newpar,Request.Form("hdd_where")}"
where hdd_where.value (hidden html input) can be "WHERE plro_ListName=\"Test\"" or something like it
I also specify on the GridView the propriety DataKeysNames = "plro_ID"
That's All
Thank's for you help
Francy
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I would like to see the markup (definition) of the SqlDataSource control in the web page if you don't mind.
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I hope this is what you asked:
<asp:SqlDataSource ID="MySqlDataSource" runat="server" ConflictDetection="CompareAllValues"
DeleteCommand="DELETE FROM [t_plro_PriceListRoundings] WHERE [plro_ID] = @original_plro_ID"
InsertCommand="INSERT INTO [t_plro_PriceListRoundings] ([plro_PriceMinValue], [plro_PriceMaxValue], [plro_RoundingValue], [plro_ListName], [plro_FixedAmmount]) VALUES (@plro_PriceMinValue,@plro_PriceMaxValue, @plro_RoundingValue, @plro_ListName, @plro_FixedAmmount)"
OldValuesParameterFormatString="original_{0}" ProviderName="System.Data.SqlClient"
SelectCommand="SELECT * FROM [t_plro_PriceListRoundings]"
UpdateCommand="UPDATE [t_plro_PriceListRoundings] SET [plro_PriceMinValue] = @plro_PriceMinValue, [plro_PriceMaxValue] = @plro_PriceMaxValue, [plro_RoundingValue] = @plro_RoundingValue, [plro_ListName] = @plro_ListName, [plro_FixedAmmount] = @plro_FixedAmmount WHERE [plro_ID] = @original_plro_ID"
EnableCaching="True"
OnSelecting="MySqlDataSource_Selecting"
OnUpdating="MySqlDataSource_Updating" FilterExpression="{0}">
<DeleteParameters>
<asp:Parameter Name="original_plro_ID" Type="Int32" DefaultValue="" />
<asp:Parameter Name="original_plro_PriceMinValue" Type="Decimal" />
<asp:Parameter Name="original_plro_PriceMaxValue" Type="Decimal" />
<asp:Parameter Name="original_plro_RoundingValue" Type="Decimal" />
<asp:Parameter Name="original_plro_ListName" Type="String" />
<asp:Parameter Name="original_plro_FixedAmmount" Type="Decimal" />
</DeleteParameters>
<UpdateParameters>
<asp:Parameter Name="plro_PriceMinValue" Type="Decimal" />
<asp:Parameter Name="plro_PriceMaxValue" Type="Decimal" />
<asp:Parameter Name="plro_RoundingValue" Type="Decimal" />
<asp:Parameter Name="plro_ListName" Type="String" />
<asp:Parameter Name="plro_FixedAmmount" Type="Decimal" />
<asp:Parameter Name="original_plro_ID" Type="Int32" />
<asp:Parameter Name="original_plro_PriceMinValue" Type="Decimal" />
<asp:Parameter Name="original_plro_PriceMaxValue" Type="Decimal" />
<asp:Parameter Name="original_plro_RoundingValue" Type="Decimal" />
<asp:Parameter Name="original_plro_ListName" Type="String" />
<asp:Parameter Name="original_plro_FixedAmmount" Type="Decimal" />
</UpdateParameters>
<InsertParameters>
<asp:Parameter Name="plro_PriceMinValue" Type="Decimal" />
<asp:Parameter Name="plro_PriceMaxValue" Type="Decimal" />
<asp:Parameter Name="plro_RoundingValue" Type="Decimal" />
<asp:Parameter Name="plro_ListName" Type="String" />
<asp:Parameter Name="plro_FixedAmmount" Type="Decimal" />
</InsertParameters>
<FilterParameters>
<asp:FormParameter FormField="hdd_Where" Name="test" />
</FilterParameters>
</asp:SqlDataSource>
I don't use any event , if you see any of them it was just for testing.
ex:
hdd_Where.value = "WHERE plro_ListName = \"Test\""
Thank you
Francy
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That's what I would like to see and it's clear enough except a couple of redundant update/delete parameters. However, one thing that strikes me most is the value of the hidden element:
"<code>WHERE</code> plro_ListName = \"Test\"" .
Are you sure that you have the keyword WHERE in the filter expression?
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No , sorry my mistake. In the hidden element I only have plro_ListName =\"Test\"
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<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title runat="server" id="title1">Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="CategoryID"
DataSourceID="SqlDataSource1">
<Columns>
<asp:CommandField HeaderText="Action" ShowEditButton="True" ShowDeleteButton="True" />
<asp:BoundField DataField="CategoryID" HeaderText="CategoryID" InsertVisible="False"
ReadOnly="True" SortExpression="CategoryID" />
<asp:BoundField DataField="CategoryName" HeaderText="CategoryName" SortExpression="CategoryName" />
<asp:BoundField DataField="Description" HeaderText="Description" SortExpression="Description" />
</Columns>
</asp:GridView>
<br />
<asp:HiddenField ID="hdd_Where" runat="server" Value="CategoryName ='Test'" />
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:NorthwindConnection %>"
DeleteCommand="DELETE FROM [Categories] WHERE [CategoryID] = @original_CategoryID"
InsertCommand="INSERT INTO [Categories] ([CategoryName], [Description]) VALUES (@CategoryName, @Description)"
SelectCommand="SELECT [CategoryID], [CategoryName], [Description] FROM [Categories]"
UpdateCommand="UPDATE [Categories] SET [CategoryName] = @CategoryName, [Description] = @Description WHERE [CategoryID] = @original_CategoryID "
EnableCaching="True"
FilterExpression="{0}"
ConflictDetection="CompareAllValues"
OldValuesParameterFormatString="original_{0}"
ProviderName="System.Data.SqlClient">
<DeleteParameters>
<asp:Parameter Name="original_CategoryID" Type="Int32" />
</DeleteParameters>
<UpdateParameters>
<asp:Parameter Name="CategoryName" Type="String" />
<asp:Parameter Name="Description" Type="String" />
<asp:Parameter Name="original_CategoryID" Type="Int32" />
<asp:Parameter Name="original_CategoryName" Type="String" />
</UpdateParameters>
<InsertParameters>
<asp:Parameter Name="CategoryName" Type="String" />
<asp:Parameter Name="Description" Type="String" />
</InsertParameters>
<FilterParameters>
<asp:FormParameter FormField="hdd_Where" Name="test" />
</FilterParameters>
</asp:SqlDataSource>
<asp:Button runat="server" ID="btnFilter" Text="Filter" />
<br />
<br />
<asp:DetailsView ID="DetailsView1" runat="server" AutoGenerateRows="False" DataKeyNames="CategoryID"
DataSourceID="SqlDataSource1" DefaultMode="Insert" Height="50px" Width="125px">
<Fields>
<asp:BoundField DataField="CategoryID" HeaderText="CategoryID" InsertVisible="False"
ReadOnly="True" SortExpression="CategoryID" />
<asp:BoundField DataField="CategoryName" HeaderText="CategoryName" SortExpression="CategoryName" />
<asp:BoundField DataField="Description" HeaderText="Description" SortExpression="Description" />
<asp:CommandField ShowInsertButton="True" />
</Fields>
</asp:DetailsView>
<br />
</div>
</form>
</body>
</html>
The DetailsView control is only used to insert new records.
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I tried your example but when updating,deleting,and inserting I recive the following error message:
The index "PK_Categories" for table "dbo.Categories" (RowsetId 72057594038517760) resides on a read-only filegroup, which cannot be modified.
Do you know what does it mean?
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Fr235166 wrote: The index "PK_Categories" for table "dbo.Categories" (RowsetId 72057594038517760) resides on a read-only filegroup, which cannot be modified.
Read-Only FileGroups[^]
Make sure it's not read-only.
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Thank you, I managed to resolve the sql error.
I can't find any differences between the example you wrote and my page , but when I create the same page from scratches it works.
Thank you again
Francy
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Glad to hear it's working. Forza Italia in World Cup  ! Ciao.
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Hi.
I have a little problem. I have a data extracted from database, which I need to load into the DataGrid but I have to do it dynamically. I tried to do that but failed.
Does anyone have an experience with doing so and can help me out? Here's the peice of my code.
Thanks a lot for help.
' Get DataBase data
rdrItm = cmd.ExecuteReader()
'Generate DataGrid
Dim dg As New DataGrid
dg.ID = "dg" & newOrd.GetOrdId 'newOrd.GetOrdId is an Order # I get from class
dg.DataSource = rdrItm
dg.AutoGenerateColumns = False
Dim col1 As New TemplateColumn
col1.HeaderText = "SKU"
Dim lbl As New Label
lbl.ID = "lbl_sku"
' Here's where I'm stuck. I can see header but....
' I need to add this label as TemplateColumn 
' with a proper data. Plus I will have TextBoxes as well later on.
dg.Columns.Add(col1)
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I suggest adding the column in design view and make it visible or invisible when you need it. Adding a template column dynamically seems like to much effort.
how vital enterprise application are for proactive organizations leveraging collective synergy to think outside the box and formulate their key objectives into a win-win game plan with a quality-driven approach that focuses on empowering key players to drive-up their core competencies and increase expectations with an all-around initiative to drive up the bottom-line. But of course, that's all a "high level" overview of things
--thedailywtf 3/21/06
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Cannot do in design time. The reason is that I don't know how many DataGrids I need.
The number of DataGrids depends on how many orders the customer selects to process in previous page. If the # is 2 I need 2 Grids, if 1 I need 1 Grid and so on...
I actually figured out how to do them dynamically but there are other issues that I cannot solve.
By making DataGrids generated dynamically I had to create a calss file that goes all the work with loading but that class cannot have any calculations on columns (don't ask me why). I've tried different things and to no success. For example I have quantity field and weights field so I was able to create totalweigth field for each item. But when I try to store total weight variable in grand total weight variable (all itmes togheter) it doesn't work. Haaaaaaaaaaaaa.
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 . It's funny. I used the same article to create my class file.
Thanks,
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You either add the label, textboxes in the your custom template definition like you see in the article or create an event handler for the ItemCreated event of the dynamic datagrid, you then add the label . textboxes to each datagrid item at the template column.
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