Can you return values from WINUI ContentDialog controls?

Question

I am building a weather related application. It's C# using WINUI3. Everything was going swimmingly, until I hit this issue...

I have a XAML page as follows:

<Page
    x:Class="WeatherStudio.Pages.AddSitePage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

    <StackPanel VerticalAlignment="Stretch" HorizontalAlignment="Stretch">
        <TextBlock Text="Please choose a site to add:" TextWrapping="Wrap" />
        <ComboBox Name="cboSites" ItemsSource="{x:Bind sites}" SelectionChanged="cboSites_SelectionChanged"/>
    </StackPanel>

</Page>

The calling page has a button, which when pressed, loads the above XAML into a ContentDialog and shows it to the user. The code-behind on the ContentDialog populates the combobox just fine.

private async void btnAddSite_Click(object sender, RoutedEventArgs e)
        {
            ContentDialog dialog = new ContentDialog();

            // XamlRoot must be set in the case of a ContentDialog running in a Desktop app
            dialog.XamlRoot = this.XamlRoot;
            dialog.Style = Application.Current.Resources["DefaultContentDialogStyle"] as Style;
            dialog.Title = "Choose new site";
            dialog.PrimaryButtonText = "Add Site";
            dialog.CloseButtonText = "Cancel";
            dialog.DefaultButton = ContentDialogButton.Primary;
            dialog.Content = new AddSitePage();

            ContentDialogResult result = await dialog.ShowAsync();

        }

The problem is after the user has hit the primary button, I cannot fathom how to see what they selected. I've tried bindings, public properties, and such and keep running into the same issue - what happens in the ContentDialog is not visible to me afterwards.

Now, I could refactor this into a regular page - but before I do that, is it possible for me to get a result like that from a ContentDialog?

Thanks,

Jason

Answer 1

You can create methods to get values from your AddSitePage.

AddSitePage.xaml.cs

using Microsoft.UI.Xaml.Controls;
using System.Collections.ObjectModel;

namespace ContentDialogs;

public sealed partial class AddSitePage : Page
{
    public AddSitePage()
    {
        this.InitializeComponent();
    }

    public ObservableCollection<string> sites = new()
    {
        "Site A",
        "Site B",
        "Site C",
    };

    public string? GetSelectedSite() => this.cboSites.SelectedItem as string;
}

And get the selected item like this:

if (await dialog.ShowAsync() is ContentDialogResult.Primary)
{
    this.selectedSite.Text = addSitePage.GetSelectedSite();
}