x:Bind 不适用于 Listview 和 ObservableCollection

Question

i want to read some data from sqlite and bind them to listview this is my codes:

public ObservableCollection<ChapterProperty> Chapters { get; set; } = new();

using var db = new AlAnvarDBContext();
Chapters = new ObservableCollection<ChapterProperty>(await db.Chapters.ToListAsync());

and my xaml

<ListView ItemsSource="{x:Bind Chapters}">
            <ListView.ItemTemplate>
                <DataTemplate x:DataType="tables:ChapterProperty">
                    <StackPanel>
                        <TextBlock Text="{x:Bind Name}"/>
                    </StackPanel>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>

but my view is not updated and i cant see items. where is wrong?

Answer 1

You bind to Chapters using a OneTime binding:

<ListView ItemsSource="{x:Bind Chapters}">

then later replace Chapters:

Chapters = new ObservableCollection<ChapterProperty>(await db.Chapters.ToListAsync());

x:Bind is OneTime by default. Also unclear if Chapters is setup to dispatch PropertyChanged notifications. If it isn't, then the binding wouldn't update on a property change anyways.

Answer 2

Instead of creating a new collection at runtime like this:

Chapters = new ObservableCollection<ChapterProperty>(await db.Chapters.ToListAsync());

...you should modify the already existing collection:

var chapters = await db.Chapters.ToListAsync();
Chapters.Clear();
if (chapters != null)
foreach (var chapter in chapters)
     Chapers.Add(chapter);

Remove the setter to make sure that your initial collection is never replaced:

public ObservableCollection<ChapterProperty> Chapters { get; } = new();

If you replace the collection with another one each on each update, there is no reason to use an ObservableCollection<T> in the first place.

Answer 3

You should use TemplateBinding instead

https://docs.microsoft.com/en-us/windows/uwp/xaml-platform/templatebinding-markup-extension