Question

I am new to WPF.

I have a database table with 2 columns: Category, Type. Primary key combination is (Category, Type). Type is subordinate to Category, meaning 1 Category containing multiple Type.

Now, in my WPF UI, I have 2 comboBox controls. The first bind to distinct category list in the DB table. I have done it by binding the control to a DB view of distinct(Category). The second needs to show Type list belonging to the category currently selected in first control.

I did research but have no idea how to easily do it. I tried creating a stored procedure to select the wanted Type value list based on Category given, but don’t know how to pass the selected Category to the stored procedure in XAML. Must I use code rather than XAML to do it? What is your suggestion?

Thanks a lot

Answer 1

I would create an object to hold your categories that contain each type possible for that category. Something like…

public class Category
{
    public ObservableCollection<string> Types { get; set; }
}

Then when you initialize every Category, you can set which Types are allowed in…

public class MyClass
{
    public ObservableCollection<Category> Categories { get; set; }
    public MyClass()
    {
         InitializeComponent();
         ObservableCollection MyTypes = new ObservableCollection();
         MyTypes.Add("type1");
         MyTypes.Add("type2");
         MyTypes.Add("Type3");
         Categories.Add(new Category() { Types = MyTypes });
         //Probably a more elegant way to do this, but hard to say based on information given

         this.DataContext = this;
    }
}

Lastly you can bind the first combobox to the category list, and the second to the Types list of the selected item of the other combobox.

<ComboBox Name="cboCategory" ItemsSource = "{Binding Categories}" />

<ComboBox ItemsSource = "{Binding ElementName=cboCategory, Path=SelectedItem.Types}" />