应用程序中有一个ComboBox
绑定到一组项目。有些情况下,用户可以从ComboBox
中选择一个项目,但所选项目可能还没有准备就绪,因此ComboBox
所选项目必须返回到上一个选定项目(或集合中的其他项目) ),但在当前应用程序中ComboBox
始终显示用户选择的项目,而不是在设置它并调用通知属性更改后检索有效项目。
流动是一个简化的代码,显示了问题。
public partial class MainWindow : Window, INotifyPropertyChanged
{
private List<Customer> _Customers = new List<Customer>();
public List<string> CustomerNames
{
get
{
var list = new List<string>();
foreach (var c in _Customers)
{
list.Add(c.Name);
}
return list; ;
}
}
public string CustomerName
{
get
{
var customer = _Customers.Where(c => c.IsReady).FirstOrDefault();
return customer.Name;
}
set
{
NotifyPropertyChanged("CustomerName");
}
}
public MainWindow()
{
SetupCustomers();
InitializeComponent();
this.DataContext = this;
}
private void SetupCustomers()
{
_Customers.Add(new Customer("c1", true));
_Customers.Add(new Customer("c2", false));
_Customers.Add(new Customer("c3", false));
}
public event PropertyChangedEventHandler PropertyChanged;
protected void NotifyPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
public class Customer
{
public Customer(string name, bool isReady)
{
this.Name = name;
this.IsReady = isReady;
}
public bool IsReady { get; set; }
public string Name { get; set; }
public override bool Equals(object obj)
{
return base.Equals(obj);
}
public override int GetHashCode()
{
return base.GetHashCode();
}
}
<Window x:Class="TryComboboxReset.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid>
<ComboBox Width="100"
Height="25"
ItemsSource="{Binding Path=CustomerNames, Mode=OneWay}"
SelectedItem="{Binding Path=CustomerName, Mode=TwoWay}"/>
</Grid>
答案 0 :(得分:1)
问题是UI线程,我使用调度程序来解决这个问题
public partial class MainWindow : Window, INotifyPropertyChanged
{
private ObservableCollection<Customer> _Customers =
new ObservableCollection<Customer>();
public ObservableCollection<Customer> CustomerNames
{
get
{
return _Customers;
}
}
public Customer CustomerName
{
get
{
return _Customers.Where(c => c.IsReady == true).FirstOrDefault();
}
set
{
// Delay the revert
Application.Current.Dispatcher.BeginInvoke(
new Action(() => NotifyPropertyChanged("CustomerName")), DispatcherPriority.ContextIdle, null);
}
}
public MainWindow()
{
SetupCustomers();
InitializeComponent();
this.DataContext = this;
}
private void SetupCustomers()
{
_Customers.Add(new Customer("c1", true));
_Customers.Add(new Customer("c2", false));
_Customers.Add(new Customer("c3", false));
CustomerName = _Customers.Where(c => c.IsReady == true).FirstOrDefault();
}
public event PropertyChangedEventHandler PropertyChanged;
protected void NotifyPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
public class Customer
{
public Customer(string name, bool isReady)
{
this.Name = name;
this.IsReady = isReady;
}
public bool IsReady { get; set; }
public string Name { get; set; }
}
<ComboBox Width="400"
Height="25"
ItemsSource="{Binding Path=CustomerNames}"
SelectedValue="{Binding CustomerName,Mode=TwoWay}" >
<ComboBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}"/>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
答案 1 :(得分:0)
您实际上并未在设置器中设置所选客户名称的值,并且您的getter总是会返回第一个&#34; ready&#34;它找到的客户名称......
如果我正确理解问题,你需要做更多的事情:
private string _customerName = null;
public string CustomerName
{
get
{
if(_customerName == null)
{
_customerName = _Customers.Where(c => c.IsReady).FirstOrDefault().Name;
}
return _customerName;
}
set
{
_customerName = value;
NotifyPropertyChanged("CustomerName");
}
}