我是WPF的新手，并尝试使用MVVM框架构建示例应用程序。我的应用程序有一个xaml文件，其中包含一些用于输入客户信息的文本框，用于显示状态的组合框和一个保存按钮。所有数据绑定都是通过ViewModel（CustomerViewMode）完成的，ViewModel具有对Model（Customer）的引用，包含必需的字段及其 Getter，二传手。 viewModel具有CustomerList属性。 单击“保存”按钮，我想在ListBox中显示Customer的FirstName和LastName属性。这就是问题所在。我调试了代码， （单击后面代码中的按钮事件），我可以看到CustomerList具有第一个Customer对象及其所有详细信息，但它没有显示在列表框中。 我的代码是： 顾客（型号）;
enter code here
namespace SampleMVVM.Models
{
class Customer : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private String _firstName;
private String _lastName;
private Address _customerAddress;
public String FirstName
{
get { return _firstName; }
set
{
if (value != _firstName)
{
_firstName = value;
RaisePropertyChanged("FirstName");
}
}
}
public String LastName
{
get { return _lastName; }
set
{
if (value != _lastName)
{
_lastName = value;
RaisePropertyChanged("LastName");
}
}
}
public Address CustomerAddress
{
get { return _customerAddress; }
set
{
if (value != _customerAddress)
{
_customerAddress = value;
RaisePropertyChanged("CustomerAddress");
}
}
}
private void RaisePropertyChanged(string propertyName)
{
var handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
}
}
地址（型号）
namespace SampleMVVM.Models
{
class Address : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private string _addressLine1;
private string _addressLine2;
private string _city;
//private string _selectedState;
private string _postalCode;
private string _country;
public String AddressLine1
{
get { return _addressLine1; }
set
{
if (value != _addressLine1)
{
_addressLine1 = value;
RaisePropertyChanged(AddressLine1);
}
}
}
public String AddressLine2
{
get { return _addressLine2; }
set
{
if (value != _addressLine2)
{
_addressLine2 = value;
RaisePropertyChanged(AddressLine2);
}
}
}
public String City
{
get { return _city; }
set
{
if (value != _city)
{
_city = value;
RaisePropertyChanged(City);
}
}
}
public String PostalCode
{
get { return _postalCode; }
set
{
if (value != _postalCode)
{
_postalCode = value;
RaisePropertyChanged(PostalCode);
}
}
}
public String Country
{
get { return _country; }
set
{
if (value != _country)
{
_country = value;
RaisePropertyChanged(Country);
}
}
}
private void RaisePropertyChanged(string propertyName)
{
var handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
}
}
CustomerViewModel：
namespace SampleMVVM.ViewModels
{
class CustomerViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private Customer _customer;
RelayCommand _saveCommand;
private List<String> _stateList = new List<string>();
private string _selectedState;
private ObservableCollection<Customer> _customerList = new ObservableCollection<Customer>();
//public CustomerViewModel(ObservableCollection<Customer> customers)
//{
// _customers = new ListCollectionView(customers);
//}
public Customer CustomerModel
{
get { return _customer; }
set
{
if (value != _customer)
{
_customer = value;
RaisePropertyChanged("CustomerModel");
}
}
}
public List<String> StateList
{
get
{
return _stateList;
}
set { _stateList = value; }
}
public ObservableCollection<Customer> CustomerList
{
get
{
return _customerList;
}
set
{
if (value != _customerList)
{
_customerList = value;
RaisePropertyChanged("CustomerList");
}
}
}
public CustomerViewModel()
{
CustomerModel = new Customer
{
FirstName = "Fred",
LastName = "Anders",
CustomerAddress = new Address
{
AddressLine1 = "Northeastern University",
AddressLine2 = "360, Huntington Avenue",
City = "Boston",
PostalCode = "02115",
Country = "US",
}
};
StateList = new List<String>
{
"Alaska", "Arizona", "California", "Connecticut", "Massachusetts", "New Jersey", "Pennsylvania", "Texas"
};
SelectedState = StateList.FirstOrDefault();
}
public String SelectedState
{
get { return _selectedState; }
set
{
if (value != _selectedState)
{
_selectedState = value;
RaisePropertyChanged(SelectedState);
}
}
}
private void RaisePropertyChanged(string propertyName)
{
var handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
}
}
CustomerInfo.xaml（视图）
<UserControl x:Class="SampleMVVM.Views.CustomerInfo"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:ViewModels="clr-namespace:SampleMVVM.ViewModels"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<UserControl.DataContext>
<ViewModels:CustomerViewModel />
</UserControl.DataContext>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
</Grid.RowDefinitions>
<!--Starting label-->
<TextBlock FontSize="18" FontFamily="Comic Sans MS" FontWeight="ExtraBlack"
Foreground="Navy"
Grid.Row="0" HorizontalAlignment="Center">
<TextBlock.Text>
Customer Information:
</TextBlock.Text>
</TextBlock>
<TextBlock Text="First name: " Grid.RowSpan="2" HorizontalAlignment="Left" VerticalAlignment="Top"
Grid.Row="1" Width="80px" Height="50px" Margin="40,5,0,0"/>
<TextBox Text="{Binding CustomerModel.FirstName}" Grid.RowSpan="2" HorizontalAlignment="Left"
VerticalAlignment="Top"
Grid.Row="1" Grid.Column="1" Width="80px" Height="20px" Margin="20,5,0,0" Name="fname"/>
<TextBlock Text="Last Name: " Grid.RowSpan="2" HorizontalAlignment="Left" VerticalAlignment="Top"
Grid.Row="2" Width="80px" Height="50px" Margin="40,5,0,0"/>
<TextBox Text="{Binding CustomerModel.LastName}" Grid.RowSpan="2" HorizontalAlignment="Left"
VerticalAlignment="Top"
Grid.Row="2" Grid.Column="1" Width="80px" Height="20px" Margin="20,5,0,0" Name="lname"/>
<TextBlock Text="Address: " Grid.RowSpan="2" HorizontalAlignment="Left" VerticalAlignment="Top"
Grid.Row="3" Width="80px" Height="50px" Margin="40,5,0,0"/>
<TextBox Text="{Binding CustomerModel.CustomerAddress.AddressLine1}" Grid.RowSpan="2" HorizontalAlignment="Left"
VerticalAlignment="Top"
Grid.Row="3" Grid.Column="1" Width="160px" Height="20px" Margin="20,5,0,0"/>
<TextBox Text="{Binding CustomerModel.CustomerAddress.AddressLine2}" Grid.RowSpan="2" HorizontalAlignment="Left"
VerticalAlignment="Top"
Grid.Row="4" Grid.Column="1" Width="160px" Height="30px" Margin="20,5,0,0"/>
<TextBlock Text="City: " Grid.RowSpan="2" HorizontalAlignment="Left" VerticalAlignment="Top"
Grid.Row="5" Width="80px" Height="20px" Margin="40,5,0,0"/>
<TextBox Text="{Binding CustomerModel.CustomerAddress.City}" Grid.RowSpan="2" HorizontalAlignment="Left"
VerticalAlignment="Top"
Grid.Row="5" Grid.Column="1" Width="80px" Height="20px" Margin="20,5,0,0"/>
<TextBlock Text="State: " Grid.RowSpan="2" HorizontalAlignment="Left" VerticalAlignment="Top"
Grid.Row="6" Width="80px" Height="20px" Margin="40,5,0,0"/>
<ComboBox Grid.RowSpan="2" HorizontalAlignment="Left" Name="listOfSates"
VerticalAlignment="Top"
Grid.Row="6" Grid.Column="1" Width="80px" Height="20px" Margin="20,5,0,0"
ItemsSource="{Binding Path=StateList}"
SelectedItem="{Binding Path=SelectedState}"
SelectionChanged="ComboBox_SelectionChanged"
>
</ComboBox>
<TextBlock Text="PostalCode: " Grid.RowSpan="2" HorizontalAlignment="Left" VerticalAlignment="Top"
Grid.Row="7" Width="80px" Height="20px" Margin="40,5,0,0"/>
<TextBox Text="{Binding CustomerModel.CustomerAddress.PostalCode}" Grid.RowSpan="2" HorizontalAlignment="Left"
VerticalAlignment="Top"
Grid.Row="7" Grid.Column="1" Width="80px" Height="20px" Margin="20,5,0,0"/>
<TextBlock Text="Country: " Grid.RowSpan="2" HorizontalAlignment="Left" VerticalAlignment="Top"
Grid.Row="8" Width="80px" Height="20px" Margin="40,5,0,0"/>
<TextBox Text="{Binding CustomerModel.CustomerAddress.Country}" Grid.RowSpan="2" HorizontalAlignment="Left"
VerticalAlignment="Top"
Grid.Row="8" Grid.Column="1" Width="80px" Height="20px" Margin="20,5,0,0"/>
<Button Content="Save" Grid.RowSpan="2" HorizontalAlignment="Left" VerticalAlignment="Top"
Grid.Row="9" Width="50px" Height="20px" Name="savebtn" Margin="40,5,0,0"
Click="savebtn_Click"/>
<ListBox Name="cList" ItemsSource="{Binding Path=CustomerList}"
HorizontalAlignment="Left"
VerticalAlignment="Top"
Grid.Row="1" Grid.Column="2" Grid.RowSpan="2" Width="200px" Height="300px" Margin="200,5,0,0">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<TextBlock Text="{Binding CustomerModel.FirstName}"
FontWeight="Bold" Foreground="Navy"/>
<TextBlock Text=", " />
<TextBlock Text="{Binding CustomerModel.LastName}"
FontWeight="Bold" Foreground="Navy"/>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
CustomerInfo（课程背后的代码）
namespace SampleMVVM.Views
{
/// <summary>
/// Interaction logic for CustomerInfo.xaml
/// </summary>
public partial class CustomerInfo : UserControl
{
public CustomerInfo()
{
InitializeComponent();
//checkvalue();
}
private void savebtn_Click(object sender, RoutedEventArgs e)
{
////Customer c = new Customer();
////c.FirstName = fname.Text;
////c.LastName = lname.Text;
//CustomerViewModel cvm = new CustomerViewModel();
//cvm.CustomerModel.FirstName = fname.Text;
//cvm.CustomerModel.LastName = lname.Text;
//List<CustomerViewModel> customerList = new List<CustomerViewModel>();
//customerList.Add(cvm);
var viewModel = DataContext as CustomerViewModel;
if (viewModel != null)
{
//viewModel.ShowCustomerInfo();
String strfname = viewModel.CustomerModel.FirstName;
String strname = viewModel.CustomerModel.LastName;
viewModel.CustomerList.Add(viewModel.CustomerModel);
String str1 = viewModel.CustomerList.FirstOrDefault().FirstName;
int i = viewModel.CustomerList.Count();
//cList.ItemsSource = viewModel.CustomerList;
}
}
private void ComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
CustomerViewModel cvm = new CustomerViewModel();
cvm.SelectedState = listOfSates.SelectedItem.ToString();
}
}
}
我只是无法理解我哪里出错了......有人请帮忙
答案 0 :(得分：3)
您只需在代码中创建一个CustomerModel对象的新实例（在Customer View Model构造函数中）。因此，您不断更新同一客户对象，而不是创建新客户对象。
在点击处理程序结束时，您应该执行
viewModel.CustomerModel = new Customer();
<强>无论其
您不应该使用点击处理程序，而应在视图模型中添加ICommand以添加新客户。然后，您应该将按钮的命令绑定到视图模型中的ICommand。
答案 1 :(得分：3)
对于ListBox.ItemTemplate中的正确绑定：
<TextBlock Text="{Binding FirstName}"
FontWeight="Bold" Foreground="Navy"/>
<TextBlock Text="{Binding LastName}"
FontWeight="Bold" Foreground="Navy"/>
DataContext的{{1}}已经是客户。
答案 2 :(得分：2)
您绑定了不是walid的CustomerLIst.FirstName，因为innterconent将检查listbox itemssource旁边的属性名称customerlist。并且因为它不是它们然后它会引发一个无声错误但是不会显示到GUI中，你需要做的就是提供像firstname和lastname这样的属性名。
除了你在列表框中的绑定之外，其他任何事情都可以。只需替换下面的列表框绑定即可。
<TextBlock Grid.Row="0"
Grid.Column="2"
HorizontalAlignment="Center"
VerticalAlignment="Center"
Text="List of Customers" />
<ListBox Name="cList"
Grid.Row="1"
Grid.RowSpan="8"
Grid.Column="2"
ItemsSource="{Binding CustomerList}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<TextBlock FontWeight="Bold"
Foreground="Black"
Text="{Binding FirstName}" />
<TextBlock Text=", " />
<TextBlock FontWeight="Bold"
Foreground="Black"
Text="{Binding LastName}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<TextBlock Grid.Row="10"
Grid.Column="2"
HorizontalAlignment="Center"
VerticalAlignment="Center"
Text="{Binding CustomerList.Count,
StringFormat='Total Customers, ={0}'}" />
最好采取命令保证事件。
答案 3 :(得分：1)
您的问题出在以下代码行中：
RaisePropertyChanged("CustomerList");
它不适用于集合添加/删除事件。看看ObservableCollection and Item PropertyChanged。
请记住，在MVVM中，你不应该在代码背后有太多代码（如果有的话）。考虑使用命令。