C# 将参数传递给 ICommand
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Passing a parameter to ICommand
提问by Michael Harper
I have a simple button that uses a command when executed, this is all working fine but I would like to pass a text parameter when the button is clicked.
我有一个简单的按钮，在执行时使用命令，这一切正常，但我想在单击按钮时传递一个文本参数。
I think my XAML is ok, but I'm unsure how to edit my RelayCommandclass to receive a parameter:
我认为我的 XAML 没问题，但我不确定如何编辑我的RelayCommand类来接收参数：
<Button x:Name="AddCommand" Content="Add"
Command="{Binding AddPhoneCommand}"
CommandParameter="{Binding Text, ElementName=txtAddPhone}" />
public class RelayCommand : ICommand
{
private readonly Action _handler;
private bool _isEnabled;
public RelayCommand(Action handler)
{
_handler = handler;
}
public bool IsEnabled
{
get { return _isEnabled; }
set
{
if (value != _isEnabled)
{
_isEnabled = value;
if (CanExecuteChanged != null)
{
CanExecuteChanged(this, EventArgs.Empty);
}
}
}
}
public bool CanExecute(object parameter)
{
return IsEnabled;
}
public event EventHandler CanExecuteChanged;
public void Execute(object parameter)
{
_handler();
}
}
采纳答案by McGarnagle
Change Actionto Action<T>so that it takes a parameter (probably just Action<object>is easiest).
更改Action为Action<T>使其接受一个参数（可能只是Action<object>最简单的）。
private readonly Action<object> _handler;
And then simply pass it the parameter:
然后简单地将参数传递给它：
public void Execute(object parameter)
{
_handler(parameter);
}
回答by philu
You can simply do this (no change to RelayCommand or ICommand required):
您可以简单地执行此操作（无需更改 RelayCommand 或 ICommand）：
private RelayCommand _addPhoneCommand;
public RelayCommand AddPhoneCommand
{
get
{
if (_addPhoneCommand == null)
{
_addPhoneCommand = new RelayCommand(
(parameter) => AddPhone(parameter),
(parameter) => IsValidPhone(parameter)
);
}
return _addPhoneCommand;
}
}
public void AddPhone(object parameter)
{
var text = (string)parameter;
...
}
public void IsValidPhone(object parameter)
var text = (string)parameter;
...
}
回答by Jaken Herman
You could just do
你可以这样做
public ICommand AddPhoneCommand
{
get
{
return new Command<string>((x) =>
{
if(x != null) { AddPhone(x); }
};
}
}
Then, of course have your AddPhone:
然后，当然有你的AddPhone：
public void AddPhone(string x)
{
//handle x
}
