Hi,

I'm trying to make an enhanced version of the standard list box that appends
a prefix to certain items based on another field within the data source.

While I could go through and add each row seperatly to the underlying list
box, it would seem like I should be able to override something associated
with the standard control in order to have it take this action for each item
(ondatabound?). Am I right about this and if so, what routine should I
override?

Thanks,

Jeremy

Hi Jeremy,


From your description I don't recommend you write a custom ListBox to
achieve your requirement. You can still use the standard ListBox. As to
your requirement, how about regenerating the datasource? You can edit the
original datasource to add prefix to items and bind the updated datasource
to ListBox.

Please let me know if you can use this approach to solve this issue. If you
have additional questions please feel free to ask.


Regards,
Allen Chen
Microsoft Online Support

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Hi,

I guess that would be a possibility, however I'm looking at this as a more
generic solution. Its not that I want to make this modification on a one
time basis (though, I guess modifying the data prior to feeding it to the
list box might be a generic solution). However, based on the re usability of
the custom control, I think that is the most desirable.

That being said, must I take the approach of stepping through each data row
and adding it manually to the list box or can one of the data binding methods
of the control be overridden to perform this action?

Thanks,

Jeremy

"Allen Chen [MSFT]" wrote:

Hi Jeremy,
the code below. The database I used is Northwind database:

<form id="form1" runat="server">
<div>

<cc1:MyListBox Width="600" Height="400" ID="MyListBox1"
runat="server" AddAppendDataToPrefix="true"
DataSourceID="SqlDataSource1" DataTextField="CompanyName"
DataTextFieldSeparatorString=" |separator_test| "
DataTextAppendField="Address"
DataValueField="CustomerID">
</cc1:MyListBox>

<asp:SqlDataSource ID="SqlDataSource1" runat="server"
ConnectionString="<%$
ConnectionStrings:NorthwindConnectionString1 %>"
DeleteCommand="DELETE FROM [Customers] WHERE [CustomerID] =
@CustomerID"
InsertCommand="INSERT INTO [Customers] ([CustomerID],
[CompanyName], [ContactName], [ContactTitle], [Address], [City], [Region],
[PostalCode], [Country], [Phone], [Fax]) VALUES (@CustomerID, @CompanyName,
@ContactName, @ContactTitle, @Address, @City, @Region, @PostalCode,
@Country, @Phone, @Fax)"
ProviderName="<%$
ConnectionStrings:NorthwindConnectionString1.Provi derName %>"
SelectCommand="SELECT [CustomerID], [CompanyName],
[ContactName], [ContactTitle], [Address], [City], [Region], [PostalCode],
[Country], [Phone], [Fax] FROM [Customers]"
UpdateCommand="UPDATE [Customers] SET [CompanyName] =
@CompanyName, [ContactName] = @ContactName, [ContactTitle] = @ContactTitle,
[Address] = @Address, [City] = @City, [Region] = @Region, [PostalCode] =
@PostalCode, [Country] = @Country, [Phone] = @Phone, [Fax] = @Fax WHERE
[CustomerID] = @CustomerID">
<DeleteParameters>
<asp:Parameter Name="CustomerID" Type="String" />
</DeleteParameters>
<InsertParameters>
<asp:Parameter Name="CustomerID" Type="String" />
<asp:Parameter Name="CompanyName" Type="String" />
<asp:Parameter Name="ContactName" Type="String" />
<asp:Parameter Name="ContactTitle" Type="String" />
<asp:Parameter Name="Address" Type="String" />
<asp:Parameter Name="City" Type="String" />
<asp:Parameter Name="Region" Type="String" />
<asp:Parameter Name="PostalCode" Type="String" />
<asp:Parameter Name="Country" Type="String" />
<asp:Parameter Name="Phone" Type="String" />
<asp:Parameter Name="Fax" Type="String" />
</InsertParameters>
<UpdateParameters>
<asp:Parameter Name="CompanyName" Type="String" />
<asp:Parameter Name="ContactName" Type="String" />
<asp:Parameter Name="ContactTitle" Type="String" />
<asp:Parameter Name="Address" Type="String" />
<asp:Parameter Name="City" Type="String" />
<asp:Parameter Name="Region" Type="String" />
<asp:Parameter Name="PostalCode" Type="String" />
<asp:Parameter Name="Country" Type="String" />
<asp:Parameter Name="Phone" Type="String" />
<asp:Parameter Name="Fax" Type="String" />
<asp:Parameter Name="CustomerID" Type="String" />
</UpdateParameters>
</asp:SqlDataSource>

</div>
</form>

public class MyListBox : ListBox {
public string DataTextFieldSeparatorString { get; set; }
public bool AddAppendDataToPrefix { get; set; }
public string DataTextAppendField { get; set; }
protected override void PerformDataBinding(IEnumerable dataSource)
{

base.PerformDataBinding(dataSource);
StringBuilder sb = new StringBuilder();
int i = 0;
foreach (object obj in dataSource)
{

if (!string.IsNullOrEmpty(DataTextField) &&
!string.IsNullOrEmpty(DataTextAppendField))
{
string appendString = DataBinder.GetPropertyValue(obj,
DataTextAppendField, DataTextFormatString);

if (AddAppendDataToPrefix)
{
sb.Append(appendString);
if(!string.IsNullOrEmpty(appendString))
sb.Append(DataTextFieldSeparatorString);
sb.Append(DataBinder.GetPropertyValue(obj,
DataTextField, DataTextFormatString));

}
else
{
sb.Append(DataBinder.GetPropertyValue(obj,
DataTextField, DataTextFormatString));
if(!string.IsNullOrEmpty(appendString))
sb.Append(DataTextFieldSeparatorString);
sb.Append(appendString);

}
this.Items[i].Text = sb.ToString();
}
i++;
sb.Remove(0, sb.Length);
}
}

}
Please let me know if it can meet your requirement.

Regards,
Allen Chen
Microsoft Online Support

Hi Jeremy,

Have you tested my code? Can it work?

Regards,
Allen Chen
Microsoft Online Support