Question

I have several listboxes that get each of their data from a separate stored procedure.

If the user selects an option in 1 listbox, it should filter the other listboxes.

I have done this before by adding logic to the stored procedure, but sometimes it seems to get very long.

Does anyone know of a better way to approach this?

The way I have it setup now is that for each ListBox, I have an ObjectDataSource which calls a method that calls a stored proc in the database to populate the listbox.

Answer 1

You can try changing the code so that instead of having the Listbox bind directly to an ADO.Net datatable, it binds to a DataView. DataViews can be sorted and filtered independently from the underlying DataTable they are based on…

Assume LBStates is state ListBox, and lbCities is City ListBox, and dtCities is form level DataTable variable with all cities in it and it has a State Column…

     DataView dvCities = dtCities.DefaultView;       dvCities.RowFilter = 'State=' + lbStates.SelectedItem;      lbCities.DataSource = dvCities; 

Wire up a selectedIndexChanged event to the States ListBox (in initializtion code)

 lbStates.SelectedIndexChanged += lbStates_SelectedIndexChanged; 

and In the States ListBox SelectedIndexChanged event, add the same code…

  private void lbStates_SelectedIndexChanged(object sender, event e)   {      DataView dvCities = dtCities.DefaultView;       dvCities.RowFilter = 'State=' + lbStates.SelectedItem;      lbCities.DataSource = dvCities;   }