如何使用从 WPF 中的数据库获取的列表显示组合框的选择

Question

I have a ComboBox which the ItemSource is binded to a List of ESTADO , a entity in my project. The ComboBox look like this:

<ComboBox Style="{StaticResource ComboBoxStyle}" Visibility="{Binding EstadoComboBox}" Name="CatalogoEstados" DisplayMemberPath="NOMBRE" SelectedValuePath="NOMBRE" SelectedValue="{Binding Estado}" ItemsSource="{Binding Estados}">
    <i:Interaction.Triggers>
        <i:EventTrigger EventName="SelectionChanged">
            <i:InvokeCommandAction Command="{Binding SeleccionarEstadoCommand}" CommandParameter="{Binding ElementName=CatalogoEstados, Path=SelectedItem.ID}" />
        </i:EventTrigger>
    </i:Interaction.Triggers>
</ComboBox>

When I select a item in the ComboBox, the property NOMBRE of the object ESTADO who is a string is assigned to a variable of type string named Estado .

Somethimes I want the variable Estado to be assigned from the constructor like this:

Estado = pplDatosGenerales.ESTADO;

pplDatosGenerales.ESTADO is a string with the string item previously select in the ComboBox, but when I assign the variable from the constructor, the ComboBox view is not showing the item selected, the variable is assigned correctly but in the view the ComboBox appears empty as if I haven't selected anything. Why is this happening and how can I solve this? I want the ComboBox to show the value that the variable Estado has.

Answer 1

You're going to have to post more of your code. You've set SelectedValuePath to NOMBRE...if NOMBRE is a string then your SelectedValue type should be a string too, but you're instead binding it to a view model property called Estado? In which case Estado should be a string too, and in your constructor you would instead do `Estado = pplDatosGenerales.ESTADO.NOMBRE'.

I suspect the problem here is simply the SelectedValuePath setting. Remove it, and you'll probably find that this all starts working as you intend.

Answer 2

This was happening because the value of Estado was not in the ComboBox ItemSource. Once I debugged the project and saw the value of Estado was not included in the ItemSource.