Reputation: 67
I am trying to make cascading combo boxes. When I select values in combo boxes for the first time everything is OK, but when I return to first combo box and change to some other value, new items in the other combos are appended to the old items. This is my code bellow:
public Apartment()
{
InitializeComponent();
}
SqlConnection con = new SqlConnection(Connection.cnnDatabase1);
Database1DataSet ds = new Database1DataSet();
private void FillLocation()
{
//locationCombo.Items.Clear()
SqlDataAdapter daLocation= new SqlDataAdapter("select * from Location", con);
daLocation.Fill(ds, "Location");
con.Open();
locationCombo.ItemsSource = ds.Tables["Location"].DefaultView;
locationCombo.DisplayMemberPath = "Location";
locationCombo.SelectedValuePath = "IdLocation";
con.Close();
}
private void FillCity(String IdLocation)
{
/*cityCombo.Items.Clear() -- I have tried inserting this,
but I am getting an error "Operation is not valid while ItemsSource is in use.
Access and modify elements with ItemsControl.ItemsSource instead." on that part
when I reselect the combo.*/
SqlDataAdapter daCity= new SqlDataAdapter("select * from City where IdLocation= " + IdLocation, con);
daCity.Fill(ds, "City");
con.Open();
cityCombo.ItemsSource = ds.Tables["City"].DefaultView;
cityCombo.DisplayMemberPath = "City";
cityCombo.SelectedValuePath = "IdCity";
con.Close();
}
private void FillStreet(String IdCity)
{
//cityCombo.Items.Clear()
SqlDataAdapter daStreet= new SqlDataAdapter("select * from Street where IdCity= " + IdCity, con);
daStreet.Fill(ds, "Street");
con.Open();
cityCombo.ItemsSource = ds.Tables["Street"].DefaultView;
cityCombo.DisplayMemberPath = "Street";
cityCombo.SelectedValuePath = "IdStreet";
con.Close();
}
private void Window_Loaded_1(object sender, RoutedEventArgs e)
{
FillLocation();
}
private void locationCombo_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
String idLocation= locationCombo.SelectedValue.ToString();
FillCity(idLocation);
}
private void cityCombo_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
String idCity = cityCombo.SelectedValue.ToString();
FillStreet(idCity);
}
Upvotes: 0
Views: 491
Reputation: 2099
Since cityCombo.Items.Clear()
is not an option in this case as mentioned in the code comments, you can clear the datatable instead:
ds.Tables["City"].Clear();
And in order to avoid the NullReferenceException
in cityCombo_SelectionChanged
you can check the cityCombo.SelectedValue
for null.
Upvotes: 1
Reputation: 2533
Try this:
public Apartment()
{
InitializeComponent();
}
SqlConnection con = new SqlConnection(Connection.cnnDatabase1);
Database1DataSet ds = new Database1DataSet();
private void FillLocation()
{
//locationCombo.Items.Clear()
SqlDataAdapter daLocation= new SqlDataAdapter("select * from Location", con);
ds.Tables["Location"].Clear();
daLocation.Fill(ds, "Location");
con.Open();
locationCombo.ItemsSource = ds.Tables["Location"].DefaultView;
locationCombo.DisplayMemberPath = "Location";
locationCombo.SelectedValuePath = "IdLocation";
con.Close();
}
private void FillCity(String IdLocation)
{
/*cityCombo.Items.Clear() -- I have tried inserting this,
but I am getting an error "Operation is not valid while ItemsSource is in use.
Access and modify elements with ItemsControl.ItemsSource instead." on that part
when I reselect the combo.*/
if(!String.IsNullOrWhiteSpace(IdLocation))
{
ds.Tables["City"].Clear();
SqlDataAdapter daCity= new SqlDataAdapter("select * from City where IdLocation= " + IdLocation, con);
daCity.Fill(ds, "City");
con.Open();
cityCombo.ItemsSource = ds.Tables["City"].DefaultView;
cityCombo.DisplayMemberPath = "City";
cityCombo.SelectedValuePath = "IdCity";
con.Close();
}
}
private void FillStreet(String IdCity)
{
if(!String.IsNullOrWhiteSpace(IdCity))
{
s.Tables["Street"].Clear();
SqlDataAdapter daStreet= new SqlDataAdapter("select * from Street where IdCity= " + IdCity, con);
daStreet.Fill(ds, "Street");
con.Open();
cityCombo.ItemsSource = ds.Tables["Street"].DefaultView;
cityCombo.DisplayMemberPath = "Street";
cityCombo.SelectedValuePath = "IdStreet";
con.Close();
}
}
private void Window_Loaded_1(object sender, RoutedEventArgs e)
{
FillLocation();
}
private void locationCombo_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if(locationCombo.SelectedValue != null)
{
String idLocation= locationCombo.SelectedValue.ToString();
FillCity(idLocation);
}
}
private void cityCombo_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if(cityCombo.SelectedValue != null)
{
String idCity = cityCombo.SelectedValue.ToString();
FillStreet(idCity);
}
}
Upvotes: 3
Reputation: 7736
You are reusing the DataSet everywhere. So it will keep appending. As I said in the comments, either clear the DataSet or make a local one to each function.
Upvotes: 0