Using Xpath with XmlDatasource and DropDown Lists

Question

User-72198832 posted

I have two Drop Down Lists - One for PROJECTS and one for ACTIVITIES

Each PROJECT has a unique set of ACTIVITIES

My PROJECT data  contains the following Descriptions and Values:
Dropdown List displays Descr Items and Code items are selectedValues

Descr, Code
Park Maintenance, PAR
Street Maintenance, STR
Building Mantenance, BLD

ACTIVITY Data Has Descr, Act and Proj fields
Dropdown List displays Descr Items and Act items are selectedValues - Proj field is used for filtering

Sample Data:
Descr, Act, Proj
Mowing, 1, PAR
TreeTrim,2, PAR
Sweep, 1, STR
Repair, 2, STR
Paint, 1, BLD
Windows, 2, BLD

When I select a PROJECT I want only those ACTIVITIES related to that PROJECT loaded int the ACTIVITY DropDownList.
Im using Xpath to accomplish this.

Here's code I'm Using.

 Private Sub lstProject_SelectedIndexChanged(sender As Object, e As EventArgs) Handles lstProject.SelectedIndexChanged
     xmlActivities.DataFile = Server.MapPath("~\data\TRIMS_Net\") & Session("Serial") & "\Activities.xml"
     xmlActivities.XPath = "/Activity_List/Activity[ @Proj='" & sender.selectedvalue & "']"
     lstActivity.DataBind()                      'Bind to Activity List
     lstActivity.Selectedindex = -1

    End Sub

This works fine the 1st time I select a project - correct activities are loaded into Activity List.
Selecting a different Project causes its Activities to be appended to Existing Activities in Activity DropDown List
How do I get only currently selected Data via Xpath to be in Activity List?

Any help is appreciated.

Lee

Answer 1

User409696431 posted

Does your dropdownlist have AppendDataBoundItems="true"?

Answer 2

User409696431 posted

It's common to set a dropdownlist to AppendDataBoundItems="true" if you want to hard code a first option of "Select", or something similar.  This works untll you rebind the dropdownlist again, at which point it appends the new items after the existing ones.  You either have to clear the list before you rebind it, and insert the Select again, or just let AppendDataBoundItems="false" and always insert the "Select" list item in position 0 of the DDL after databinding.

Answer 3

User-72198832 posted

Found Problem.  I was binding XML Control  on every postback.

All OK Now.