WPF Combox:将SelectedItem与类成员结合

Question

我有一个具有ID(INT32(和名称(字符串(的类人。人物集合的名称以Combobox(DisplayMemberPath =" name"(显示。我想将所选项目的ID绑定到ViewModel中的属性INT32属性。

我尝试了SelectedValue =" {binding Path = selectedID，mode = twoway}"和SelectedValuePath =" {binding Path = selectedID，mode = twoway}"，两者都不起作用。

<ComboBox Name="cmbPersons"
    ItemsSource="{Binding Source={StaticResource vm},Path=Persons}"
    DisplayMemberPath="Name"
    SelectedValue="Id"
    SelectedValue="{Binding Path=SelectedId, Mode=TwoWay}"
/>

Answer 1

尝试这个。

SelectedValue="{Binding SelectedId, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
SelectedValuePath="Id"

更新：

我准备了一个工作正常的样品。我希望它能澄清您。(实施自己由您自己制作的InotifyPropertychang(

mainwindow.xaml.cs：

public partial class MainWindow : Window
{
    public ObservableCollection<Person> Persons { get; set; }
    public int SelectedId { get; set; }
    public MainWindow()
    {
        InitializeComponent();
        DataContext = this;
        Persons = new ObservableCollection<Person>
        {
            new Person { Id = 1, Name = "Raj" },
            new Person { Id = 2, Name = "Ram" }
        };
    }
}

person.cs：

public class Person
{
    public int Id { get; set; }
    public string Name { get; set; }
}

mainwindow.xaml：

   <ComboBox Width="100" Height="30" ItemsSource="{Binding Persons}" DisplayMemberPath="Name" SelectedValue="{Binding SelectedId}" SelectedValuePath="Id"/>

Answer 2

如果它主要是获取所选项目而不是绑定。

您可以在不将其绑定到额外属性的情况下获取所选项目。当选择另一个项目时，您可以使用ICollectionView在ViewModel中获取事件。

ViewModel的代码

List<PersonVm> personVms;
private ICollectionView _persons;
public ICollectionView Persons
{
    get => _persons;
    set
    {
        if (Equals(value, _persons)) return;
        _persons = value;
        OnPropertyChanged();
    }
}
// call this method in the constructor of the viewmodel
private void Init(){
    // TODO You have to add items to personVms before creating the collection
    Persons = new CollectionView(personVms);
    // Event when another item gets selected
    Persons.CurrentChanged += PersonsOnCurrentChanged;
    // moves selected index to postion 2
    Persons.MoveCurrentToPosition(2); 
}
private void PersonsOnCurrentChanged(object sender, EventArgs e)
{
    // the currently selected item
    PersonVm personVm = (PersonVm)Persons.CurrentItem;
    // the currently selected index
    int personsCurrentPosition = Persons.CurrentPosition;
}

xaml

<ComboBox 
    ItemsSource="{Binding Persons}" 
    DisplayMemberPath="Name"/>