如何通过wpf命令传递整数?

Question

我有一个ListView，它将一个月中的所有日子显示为按钮，每个按钮包含日期。当我点击其中一个按钮时，我希望它能把我带到当天的视图。按钮命令绑定到ToDayView命令。我不想为可能是一个月的每一天做一堆不同的命令。如何使用命令传递日期?

MonthView

<ListView ItemsSource="{Binding CurrentMonth.Days}" Grid.Row="1">
<ListView.ItemTemplate>
<DataTemplate>
<Button Content="{Binding DayNumber}"  Grid.Row="1" Height="20" Width="100"
Command="{Binding ToDayViewCommand}"/>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>

MonthViewModel

public class MonthViewModel : ViewModelBase
{
private readonly NavigationStore _navigationStore;
private Month _currentMonth;
public Month CurrentMonth
{
get { return _currentMonth; }
set 
{ 
_currentMonth = value;
OnPropertyChanged("CurrenMonth");
}
}
public void ToDayView(object thing)
{
// use parameter as day number
int dayNumber = 25;
// find the Day object with that day number
for(int i = 0; i < CurrentMonth.Days.Count; i++)
{
if(CurrentMonth.Days[i].DayNumber == dayNumber)
{
// give it to the view model to be displayed
_navigationStore.CurrentViewModel = new DayViewModel(CurrentMonth.Days[i], _navigationStore);
}
}
}
public BasicCommand ToDayViewCommand { get; set; }
public MonthViewModel(Month currentMonth, NavigationStore navigationStore)
{
CurrentMonth = currentMonth;
_navigationStore = navigationStore;
ToDayViewCommand = new BasicCommand(ToDayView);
}
}

BasicCommand

public class BasicCommand : CommandBase
{
readonly Action<object> _execute;
public BasicCommand(Action<object> execute)
{
_execute = execute;
}
public override bool CanExecute(object parameter) => true;
public override void Execute(object parameter)
{
_execute.Invoke(parameter);
}
}

Answer 1

您可以在XAML代码中定义命令参数:

<Button Content="{Binding DayNumber}"  Grid.Row="1" Height="20" Width="100"
Command="{Binding ToDayViewCommand}" CommandParameter="25" />

注意CommandParameter是一个依赖属性，因此你也可以使用绑定:

<Button Content="{Binding DayNumber}"  Grid.Row="1" Height="20" Width="100"
Command="{Binding ToDayViewCommand}" CommandParameter="{Binding AmountDays}" />

在命令调用的方法中，必须将对象强制转换为int类型。注意你的参数是一个字符串，如果你像我的第一个代码片段那样调用它，那么你必须使用int.Parse:

public void ToDayView(object thing)
{
// use parameter as day number
int dayNumber = int.Parse(thing.ToString());
// find the Day object with that day number
for(int i = 0; i < CurrentMonth.Days.Count; i++)
{
if(CurrentMonth.Days[i].DayNumber == dayNumber)
{
// give it to the view model to be displayed
_navigationStore.CurrentViewModel = new DayViewModel(CurrentMonth.Days[i], _navigationStore);
}
}
}