这是我的观点:
private Customer customer;
public Customer Customer
{
get { return customer; }
set { customer = value; NotifyOfPropertyChange(() => Customer); }
}
public bool CanUpdateClick
{
get
{
if (string.IsNullOrEmpty(customer.Name))
{
return false;
}
return true;
}
}
public void UpdateClick()
{
//...
}
这是我的ViewModel:
private string name;
public string Name
{
get { return name; }
set { name = value; NotifyOfPropertyChange(() => Name); }
}
这是我的模特:
{{1}}
所以我有UpdateClick方法,它完美无缺。我也有CanUpdateClick属性,但它不起作用,我不知道为什么?当文本框为空时,应禁用UI上的按钮。请帮忙!
答案 0 :(得分:3)
您可以订阅PropertyChanged
类的Customer
事件(因为您似乎是PropertyChangedBase
的子类)并在NotifyOfPropertyChanged(() => CanUpdateClick)
属性时调用Name
改变了:
// in your view model
// i'm assuming here that Customer is set before your view model is activated
protected override void OnActivate()
{
base.OnActivate();
Customer.PropertyChanged += CustomerPropertyChangedHandler;
}
protected override void OnDeactivate(bool close)
{
base.OnDeactivate(close);
// unregister handler
Customer.PropertyChanged -= CustomerPropertyChangedHandler;
}
// event handler
protected void CustomerPropertyChangedHandler(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == nameof(Customer.Name))
{
NotifyOfPropertyChange(() => CanUpdateClick);
}
}
或者,您只需在视图模型中创建Name
或CustomerName
属性即可绑定到a)使用Customer.Name
作为后备字段或b)使用普通支持字段然后在更新时设置Customer.Name
:
在您看来:
<TextBox Text="{Binding CustomerName, UpdateSourceTrigger=PropertyChanged}" Width="136"/>
以下是在视图模型中实现选项a的方法:
public string CustomerName
{
get { return Customer.Name; }
set
{
Customer.Name = value;
NotifyOfPropertyChange(); // CallerMemberName goodness
NotifyOfPropertyChange(() => CanUpdateClick);
}
}