在Xamarin Forms中，我可以绑定到要在列表视图中显示的类的列表中的属性吗？

Question

I'm new to programming and I'm trying to develop an app using Xamarin Forms. So far I was able to get most of the answers I needed from here or other tutorials, but this one was not possible.

The idea - I want to show a list of users in a listview. It cell should show his "Name" and the "Value" of a "Topic". But as the user can teach more than one topic, he has a "List", like this:

    public class User
{
    public string Name { get; set; }
    public List<Topic> Topics { get; set; }

    public User()
    {
        Topics = new List<Topic>();
        Topics.Add(new Topic { TopicName = "English", Value = 150.00 });
        Topics.Add(new Topic { TopicName = "Portuguese", Value = 120.00 });
        Topics.Add(new Topic { TopicName = "Latin", Value = 300.00 });
    }
}

public class Topic
{
    public string TopicName { get; set; }
    public double Value { get; set; }
}

My App, just to show this trial is like this:

   public App()
    {
        // The root page of your application
        var template = new DataTemplate(typeof(CustomCell));
        var users = new List<User>();
        users.Add(new App1.User { Name = "Luizinho" });
        users.Add(new App1.User { Name = "Zezinho" });
        users.Add(new App1.User { Name = "Huguinho" });

        var content = new ContentPage
        {
            Title = "StackFlow_01",
            Content = new StackLayout
            {
                VerticalOptions = LayoutOptions.Center,
                Children = {
                    //new Label {Text = "funciona" }
                    new ListView {ItemTemplate = template, ItemsSource = users  }
                    }
            }
        };

        MainPage = new NavigationPage(content);
    }

And finally the CustomCell:

   public class CustomCell : ViewCell
{
    public CustomCell()
    {
        //instantiate each of our views
        StackLayout cellWrapper = new StackLayout();
        StackLayout horizontalLayout = new StackLayout();
        Label left = new Label();
        Label right = new Label();

        //set bindings
        left.SetBinding(Label.TextProperty, "Name");
        right.SetBinding(Label.TextProperty, "TopicName");

        //add views to the view hierarchy
        horizontalLayout.Children.Add(left);
        horizontalLayout.Children.Add(right);
        cellWrapper.Children.Add(horizontalLayout);
        View = cellWrapper;
    }
}

So, the Name binded to the Left label works fine (and most of the examples around to show something in the first "level" of the class), but how can I bind the Right label to the Value of Portuguese topic? Is it possible?

I know there should be also an IValueConverter, but the biding path is really what I'm not getting.

Answer 1

您可以尝试绑定到列表中的第一个元素

right.SetBinding(Label.TextProperty, "Topics[0].TopicName");

Answer 2

Each user has own Topics, so you will need to decide what topic you want to bind to at some point unless you want to bind list of topics to another sub-view list. You probably will need to derive from DataTemplateSelector to make such decision