[英]C# WPF MVVM ComboBox SelectedItem
I know that it's been here a million times but I don't know what's wrong in my code. 我知道已经到过一百万次了,但是我不知道我的代码有什么问题。 I tried everything but the
ComboBox
is not binding SelectedItem
correctly. 我尝试了所有操作,但
ComboBox
未正确绑定SelectedItem
。 Here is my complete sandbox solution. 这是我完整的沙箱解决方案。 You can also find it on GitHub ( https://github.com/LukasNespor/ComboBoxBinding ).
您也可以在GitHub( https://github.com/LukasNespor/ComboBoxBinding )上找到它。
BindableBase.cs BindableBase.cs
public class BindableBase : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public virtual void RaisePropertyChanged(string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
ContactModel.cs ContactModel.cs
public class ContactModel : BindableBase
{
private int _Id;
public int Id
{
get { return _Id; }
set
{
_Id = value;
RaisePropertyChanged(nameof(Id));
}
}
private string _Name;
public string Name
{
get { return _Name; }
set
{
_Name = value;
RaisePropertyChanged(nameof(Name));
}
}
private string _Phone;
public string Phone
{
get { return _Phone; }
set
{
_Phone = value;
RaisePropertyChanged(nameof(Phone));
}
}
public override bool Equals(object obj)
{
if (obj != null || !(obj is ContactModel))
return false;
return ((ContactModel)obj).Id == this.Id;
}
public override string ToString()
{
return $"{Name} {Phone}";
}
}
MainWindow.xaml MainWindow.xaml
<Window x:Class="WpfApplication1.MainWindow"
...>
<Grid>
<ComboBox Width="200" Height="23"
SelectedItem="{Binding ViewModel.SelectedContact}" ItemsSource="{Binding ViewModel.Contacts}" />
</Grid>
MainWindows.xaml.cs MainWindows.xaml.cs
public partial class MainWindow : Window
{
public MainViewModel ViewModel { get; set; }
public MainWindow()
{
InitializeComponent();
DataContext = this;
ViewModel = new MainViewModel();
ViewModel.SelectedContact = new ContactModel
{
Id = 2,
Name = "Some Guy",
Phone = "+123456789"
};
}
}
MainViewModel.cs MainViewModel.cs
public class MainViewModel : BindableBase
{
public List<ContactModel> Contacts
{
get
{
return new List<ContactModel>
{
new ContactModel() {Id = 1, Name = "John Doe", Phone = "+166666333" },
new ContactModel() {Id = 2, Name = "Some Guy", Phone = "+123456789" }
};
}
}
private ContactModel _SelectedContact;
public ContactModel SelectedContact
{
get { return _SelectedContact; }
set
{
_SelectedContact = value;
RaisePropertyChanged(nameof(SelectedContact));
}
}
}
You need do Sync the list with the current selected item: 您需要将列表与当前所选项目同步:
1.Xaml: 1.Xaml:
<ComboBox ItemsSource="{Binding Contacts}" SelectedItem="{Binding SelectedContact}" IsSynchronizedWithCurrentItem="True" />
2.ViewModel: 2.ViewModel:
public ObservableCollection<ContactModel> Contacts { get; set; }
public MainViewModel()
{
_model = new Model {Name = "Prop Name" };
Contacts = new ObservableCollection<ContactModel>
{
new ContactModel {Id = 1, Name = "John Doe", Phone = "+166666333"},
new ContactModel {Id = 2, Name = "Some Guy", Phone = "+123456789"}
};
SelectedContact = Contacts[0];
}
private ContactModel _SelectedContact;
public ContactModel SelectedContact
{
get { return _SelectedContact; }
set
{
_SelectedContact = value;
OnPropertyChanged(nameof(SelectedContact));
}
}
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