无法以双向模式绑定条目和属性

Question

尝试创建将项目添加到列表中的简单应用程序。在 ViewModel 中绑定带有属性的条目时出现问题。

这是我的 xaml：

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:viewModels="clr-namespace:MyScoreDemo.ViewModels;assembly=MyScoreDemo"
x:Class="MyScoreDemo.Views.ClubListPage">
<StackLayout
Padding="15"
Spacing="10">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Label Text="Name:" Grid.Row="0" Grid.Column="0"/>
<Entry x:Name="EntryName" Text="{Binding Club.Name, Mode=OneWayToSource}" Grid.Row="0" Grid.Column="1"/>
<Label Text="Country:" Grid.Row="1" Grid.Column="0"/>
<Entry x:Name="EntryCountry" Text="{Binding Club.Country, Mode=OneWayToSource}" Grid.Row="1" Grid.Column="1"/>
<Button Text="Add" Command="{Binding AddCommand}" CommandParameter="{x:Reference EntryName}"
Grid.Row="2" Grid.ColumnSpan="2" Grid.Column="0" />
</Grid>
<ListView ItemsSource="{Binding Clubs}"
Margin="5">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Label Text="{Binding Path=Name}"/>
<Label Text="{Binding Path=Country}" Grid.Column="1"/>
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<StackLayout.BindingContext>
<viewModels:ClubListViewModel/>
</StackLayout.BindingContext>
</StackLayout>

和视图模型代码：

private Club _club;
public ICommand AddCommand { get; set; }
public ICommand RemoveCommand { get; set; }
public event PropertyChangedEventHandler PropertyChanged;
public ObservableCollection<Club> Clubs { get; set; }
public ClubListViewModel()
{
AddCommand = new Command(AddClub);
RemoveCommand = new Command(RemoveClub);
Clubs = new ObservableCollection<Club>();
}
public Club Club
{
get => _club;
set
{
_club = value;
OnPropertyChanged("Club");
}
}
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = "") => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
//Commands
private void AddClub()
{
}

在酒店的俱乐部设置部分中设置断点并尝试不同的模式，但它永远不会停止。

Answer 1

我需要更改的只是在我的 ViewModel 类的构造函数中添加Club = new Club();。