wpf 使用命令将参数传递到视图模型中
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Pass parameter with a command into the viewmodel
提问by Rasmus B?kgaard
I have trouble sending a parameter from my view to my viewmodel.
我无法将参数从我的视图发送到我的视图模型。
View.xaml:
查看.xaml：
In my view, I have the following:
在我看来，我有以下几点：
<TextBox
MinWidth="70"
Name="InputId"/>
<Button
Command="{Binding ButtonCommand}"
CommandParameter="{Binding ElementName=InputId}"
Content="Add"/>
View.xaml.cs:
查看.xaml.cs：
public MyView()
{
InitializeComponent();
}
public MyView(MyViewModel viewModel) : this()
{
DataContext = viewModel;
}
MyViewModel.cs:
MyViewModel.cs：
public class MyViewModel : BindableBase
{
public ICommand ButtonCommand { get; private set; }
public MyViewModel()
{
ButtonCommand = new DelegateCommand(ButtonClick);
}
private void ButtonClick()
{
//Read 'InputId' somehow.
//But DelegateCommand does not allow the method to contain parameters.
}
}
Any suggestions to, how I can pass the InputIdwhen I click the button to my viewmodel?
有什么建议，我如何InputId在单击按钮时将其传递给我的视图模型？
回答by Johannes
You need to add <object>to your delegate command like this :
您需要<object>像这样添加到您的委托命令中：
public ICommand ButtonCommand { get; private set; }
public MyViewModel()
{
ButtonCommand = new DelegateCommand<object>(ButtonClick);
}
private void ButtonClick(object yourParameter)
{
//Read 'InputId' somehow.
//But DelegateCommand does not allow the method to contain parameters.
}
Do you want to get the text of textbox change your xaml to :
您想将文本框的文本更改为：
CommandParameter="{Binding Text,ElementName=InputId}"
回答by Nawed Nabi Zada
For proper implementation of ICommand/RelayCommand have a look at this MSDNpage.
要正确实现 ICommand/RelayCommand，请查看此MSDN页面。
Summary:
概括：
public class RelayCommand : ICommand
{
readonly Action<object> _execute;
readonly Func<bool> _canExecute;
public RelayCommand(Action<object> execute)
: this(execute, null)
{
}
public RelayCommand(Action<object> execute, Func<bool> canExecute)
{
if (execute == null)
throw new ArgumentNullException("execute");
_execute = execute;
_canExecute = canExecute;
}
public bool CanExecute(object parameter)
{
return _canExecute == null || _canExecute.Invoke();
}
public event EventHandler CanExecuteChanged
{
add { CommandManager.RequerySuggested += value; }
remove { CommandManager.RequerySuggested -= value; }
}
public void Execute(object parameter)
{
_execute(parameter);
}
}
public MyViewModel()
{
ButtonCommand = new RelayCommand(ButtonClick);
}
private void ButtonClick(object obj)
{
//obj is the object you send as parameter.
}
