#1,013 – Typing Text to Select an Item in a ComboBox

If a ComboBox has focus, you can just type some text in order to select an item.  By default, the text that you enter will be matched against the property specified by the DisplayMemberPath property, or by the value of the bound object’s ToString method, if DisplayMemberPath is not specified.

In the example below, we don’t specify DisplayMemberPath, but instead specify an ItemTemplate.  If the ComboBox has focus and we start typing, the ToString method of the underlying Actor object is used to determine the object to navigate to.

        <ComboBox ItemsSource="{Binding ActorList}" Margin="20"
                  SelectedItem="{Binding SelectedActor}">
            <ComboBox.ItemTemplate>
                        <DataTemplate>
                            <StackPanel Orientation="Horizontal">
                                <Image Source="{Binding Image}" Height="100"/>
                                <StackPanel Margin="10,0">
                                    <TextBlock Text="{Binding FullName}" FontWeight="Bold" />
                                    <TextBlock Text="{Binding Dates}"/>
                                    <TextBlock Text="{Binding KnownFor}" FontStyle="Italic"/>
                                </StackPanel>
                            </StackPanel>
                        </DataTemplate>
            </ComboBox.ItemTemplate>
        </ComboBox>

If we’ve defined Actor.ToString() to return the actor’s name in a LastName, FirstName format, we can then navigate to an actor by typing their last name.  For example, entering “L” might select Hedy Lamarr.

1013-001

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#764 – Current Culture Is Used When Converting Data to A String

The CurrentCulture property of a Thread object indicates a user’s current locale, as set in the Region applet.  This value can normally be thought of as indicating the user’s location.

If you convert either numeric or date data to a string, the formatting used will depend on the current locale, as set in the Region applet and reported by the CurrentCulture property.

For example:

            double d1 = 123.456;
            DateTime date1 = DateTime.Now;

            string output = string.Format("123.456 => {0}\nNow => {1}",
                d1.ToString(),
                date1.ToString());

            MessageBox.Show(output);

If we run this code when our region is set to English (United States), we get:

764-001

But now if we switch our region to French (France) and re-run the application, we get:

764-002

Notice that the decimal point is now displayed as a comma (,) and the date format is dd/mm, rather than mm/dd.