CODEWITHSUNDEEP
c#wpfcombobox
atulya
atulya

Reputation: 539

WPF combobox update other combobox based on selection of first one

My WPF application has 2 comboboxes as follows

<ComboBox Height="23" Name="ProjectNameComboBox" Width="215" ItemsSource="{Binding}" DisplayMemberPath="name" SelectionChanged="ProjectSelection_Changed" />

<ComboBox Height="25" Name="LangaugeComboBox"  Width="108" ItemsSource="{Binding}" DisplayMemberPath="name"  />

and from the code behind I am binding using database as

ProjectNameComboBox.DataContext = dbConnector.GetProjectNames();
LangaugeComboBox.DataContext = dbConnector.GetLanguages();

project combobox contains list of projects

langauges combobox contains list of langauges.

I want to updated the langauges combobox based on project selection.

based on project selection I am able to get the langauges for that project from database, but how to set it in langauge combobox.

LangaugeComboBox.SelectedValue = dt.Rows[0][0].ToString(); is not working.

and suggestion/help?

Upvotes: 0

Views: 1997

Answers (2)

pushpraj
pushpraj

Reputation: 13669

I would advice you to start with migrating from events to binding and change notifications. That would be more WPF way.

so the code for two comboboxes become like this, I removed the SelectionChanged event handler and I'll also remove the Name unless required

<ComboBox Height="23" Width="215" ItemsSource="{Binding Projects}" DisplayMemberPath="name" SelectedItem="{Binding SelectedProject}" />
<ComboBox Height="25" Width="108" ItemsSource="{Binding Languages}" DisplayMemberPath="name" SelectedItem="{Binding SelectedLanguage}" />

then (instead of) code behind a class with following properties, then instance of this class goes as DataContext for the View

    public ObservableCollection<Project> Projects
    {
        get { return (ObservableCollection<Project>)GetValue(ProjectsProperty); }
        set { SetValue(ProjectsProperty, value); }
    }

    // Using a DependencyProperty as the backing store for Projects.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty ProjectsProperty =
        DependencyProperty.Register("Projects", typeof(ObservableCollection<Project>), typeof(ViewModel), new PropertyMetadata(null));

    public ObservableCollection<Language> Languages
    {
        get { return (ObservableCollection<Language>)GetValue(LanguagesProperty); }
        set { SetValue(LanguagesProperty, value); }
    }

    // Using a DependencyProperty as the backing store for Languages.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty LanguagesProperty =
        DependencyProperty.Register("Languages", typeof(ObservableCollection<Language>), typeof(ViewModel), new PropertyMetadata(null));

    public Project SelectedProject
    {
        get { return (Project)GetValue(SelectedProjectProperty); }
        set { SetValue(SelectedProjectProperty, value); }
    }

    // Using a DependencyProperty as the backing store for SelectedProject.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty SelectedProjectProperty =
        DependencyProperty.Register("SelectedProject", typeof(Project), typeof(ViewModel), new PropertyMetadata(null, OnSelectedProjectChanged));

    public Language SelectedLanguage
    {
        get { return (Language)GetValue(SelectedLanguageProperty); }
        set { SetValue(SelectedLanguageProperty, value); }
    }

    // Using a DependencyProperty as the backing store for SelectedLanguage.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty SelectedLanguageProperty =
        DependencyProperty.Register("SelectedLanguage", typeof(Language), typeof(ViewModel), new PropertyMetadata(null));

then finally the property change handler

    private static void OnSelectedProjectChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        View v = d as View;
        v.SelectedLanguage = //your logic here eg. v.SelectedProject.Language;
    }

so with the binding in place your language combo box will update the selected item based on the value you set to SelectedLanguage.

Upvotes: 1

Vimal CK
Vimal CK

Reputation: 3563

If your Language ComoboBox is not bounded to a complex object and it is a string collection, please try below code

LangaugeComboBox.SelectedItem = dt.Rows[0][0].ToString();

Upvotes: 0

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