如何在 WPF C# 中使用数据绑定？

Question

我想在 WPF 中将我的控件与我的视图模型绑定，并在我的数据库更新时自动更新数据控件。我实现了一个具有一些 List<myClass> 属性的视图模型，并从数据库接收数据，这些数据将保存在这些属性中。然后我将我的控件源绑定到这些属性。没关系，但是当我从数据库中获取新数据并将其保存在这些属性中时，控件数据不会更新。我如何以编程方式修复它？

这是我的代码：

public partial class MainWindow : Window
{
    ListOfPerson personList1 = new ListOfPerson();
    ListOfPerson personList2 = new ListOfPerson();
    

    public MainWindow()
    {
        InitializeComponent();
    }

    private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        personList1.People.Add(new Person { PersonName = "test1" });
        personList2.People.Add(new Person { PersonName = "test2" });

        dg.AutoGenerateColumns = false;
        PropertyPath prop = new PropertyPath("PersonName");
        Binding bind = new Binding();
        bind.Mode = BindingMode.TwoWay;
        bind.Path = prop;
        dg.Columns.Add(new DataGridTextColumn { Header = "Name", Binding = bind });
        dg.ItemsSource = personList1.People;
    }
    public void Refresh()
    {
        personList1.People = personList2.People;
    }

    private void btn_Refresh_Click(object sender, RoutedEventArgs e)
    {
        Refresh();
    }
}

public class Person : INotifyPropertyChanged
{
    private string name;

    public Person()
    {
    }

    public Person(string value)
    {
        this.name = value;
    }

    public string PersonName
    {
        get { return name; }
        set
        {
            name = value;
            OnPropertyChanged();
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    public void OnPropertyChanged([CallerMemberName] string name = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
    }
}

public class ListOfPerson : INotifyPropertyChanged
{
    private List<Person> people = new List<Person>();
    public List<Person> People
    {
        get
        {
            return people;
        }
        set
        {
            people = value;
            OnPropertyChanged();
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    public void OnPropertyChanged([CallerMemberName] string name = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
    }
}

Answer 1

您直接分配您的ItemsSource，即不是绑定。

dg.ItemsSource = personList1.People;

然而，在 Refresh 上，您替换了 personList1 的 People 集合。

personList1.People = personList2.People;

项目源仍然具有对旧集合的引用，因为您直接分配了它。您可以添加一个绑定，它会注意到项目源通过属性更改通知实现在 People 属性中更改了 ListOfPerson。这应该有效：

Binding itemsSourceBinding = new Binding
{
    Source = personList1,
    Path = new PropertyPath("People")
};
BindingOperations.SetBinding(dg, DataGrid.ItemsSourceProperty, itemsSourceBinding);

这只是处理这种情况的一种选择。另一种选择是仅使用单个 ObservableCollection<T> that you Clear and fill again or modify in between (if your replace it with a new instance like the list in your code, you run into the same issue as above). It implements the INotifyCollectionChanged 界面并通知更改，例如自动添加、删除或插入项目，这会依次更新 UI。

如何在 WPF C# 中使用数据绑定？

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