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Accepted
Richard
Asked: 2020-04-11 13:28:13 +0800 CST 2020-04-11 13:28:13 +0800 CST

How to put a default text in a ComboBox?

  • 772

I have the following comboBox

    <ComboBox x:Name="cmbBuscarPor" HorizontalAlignment="Left" Text="Buscar por " Margin="210,10,0,0" VerticalAlignment="Top" Width="120" Height="30" VerticalContentAlignment="Center">
        <ComboBoxItem Content="Nombre" HorizontalContentAlignment="Center"/>
        <ComboBoxItem Content="Apellido paterno" HorizontalContentAlignment="Center"/>
        <ComboBoxItem Content="Puesto" HorizontalContentAlignment="Center"/>
    </ComboBox>

I want to put a text that appears at startup that is not any of the options that are already default

xaml

1 Answers

  1. Best Answer

    The easiest way is to use CompositeCollectionto merge text and default data from the database directly into the ComboBox, for example:

    <ComboBox x:Name="cmbBuscarPor" SelectedIndex="0">
    <ComboBox.ItemsSource>
        <CompositeCollection>
            <ComboBoxItem Visibility="Collapsed">-- Seleccionar item --</ComboBoxItem>
            <CollectionContainer Collection="{Binding Source={StaticResource ResourceKey=MyComboOptions}}"/>
        </CompositeCollection>
    </ComboBox.ItemsSource>
</ComboBox>

    And in Resources define StaticResourceto link the options of ComboBoxto your DataContext, because the direct link in CollectionContainerdoes not work correctly.

    <Window.Resources>
    <CollectionViewSource Source="{Binding}" x:Key="MyComboOptions" />
</Window.Resources>

    This way you can define your ComboBox options only in xaml, for example

       <ComboBox x:Name="cmbBuscarPor" SelectedIndex="0">
        <ComboBox.ItemsSource>
            <CompositeCollection>
                <ComboBoxItem Visibility="Collapsed">-- Seleccionar item --</ComboBoxItem>
                <ComboBoxItem >Opction 1</ComboBoxItem>
                <ComboBoxItem >Opcion 2</ComboBoxItem>
            </CompositeCollection>
        </ComboBox.ItemsSource>
    </ComboBox>

    Another way: 

    <ComboBox SelectedIndex="0">
    <ComboBox.ItemsSource>
        <CompositeCollection>
            <ListBoxItem>Seleccione una Opción</ListBoxItem>
            <CollectionContainer Collection="{Binding Source={StaticResource TUDATASOURCE}}" />
        </CompositeCollection>
    </ComboBox.ItemsSource>
</ComboBox>

    Or like this:

    <ComboBox Name="MyComboBox"
 IsEditable="True"
 IsReadOnly="True"
 Text="-- Seleccionar Item --" />

    You'll obviously have to add your other options, but this is probably the easiest way to do it.

    However, there is a downside to this method, which is when the text inside your ComboBox will not be editable, it is still selectable. However, given the low quality and complexity of every alternative I've found to date, this is probably the best option.

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