I am new to the WPF and trying to build a sample application using the MVVM framework. My application has a xaml file which has some textboxes for inputing customer info, combo box for display of states and a save button. All the databinding is done through ViewModel(CustomerViewMode) which has a reference to the Model(Customer), containing the required fields and their Getter, setters. The viewModel has a CustomerList property. On clicking the save button, I want to display the FirstName and LastName properties of Customer in a ListBox. This is where the problem is. I debugged the code, (Click event of button in the code behind), I can see that the CustomerList has the first Customer object with all its details, but its not getting displayed in the listbox. My code is: Customer(Model);
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引用了Model（Customer），包含必需的字段及其Getter，setter。 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，（在后面的代码中单击按钮事件），我可以看到CustomerList有第一个Customer对象及其所有细节，但它没有显示在列表框中。我的代码是：客户（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));
}
}
}
}
}
Address(Model)
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:
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(view)
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(Code behind class)
CustomerInfo（类背后的代码）
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();
}
}
}
}
I just cant understand where am I going wrong...Someone please help
我只是不明白我哪里错了...有人请帮忙
4 个解决方案
#1
3
And for the correct binding in ListBox.ItemTemplate:
并且对于ListBox.ItemTemplate中的正确绑定：
<TextBlock Text="{Binding FirstName}"
FontWeight="Bold" Foreground="Navy"/>
<TextBlock Text="{Binding LastName}"
FontWeight="Bold" Foreground="Navy"/>
The DataContext of ListBoxItem is a Customer already.
ListBoxItem的DataContext已经是Customer。
#2
3
You only create a new instance of a CustomerModel object once in your code (in the Customer View Model constructor). So you are constantly updating the same customer object rather than creating a new one.
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。
At the end of your click handler you should do a
在点击处理程序的最后，你应该做一个
viewModel.CustomerModel = new Customer();
HOWEVER
然而
Rather than having a click handler you should have an ICommand in your view model for adding a new customer. Then you should bind to command of your button to the ICommand in your view model.
您可以在视图模型中使用ICommand来添加新客户，而不是使用单击处理程序。然后，您应该将按钮的命令绑定到视图模型中的ICommand。
#3
2
you were binding the CustomerLIst.FirstName which is not walid because innterconent will check for property name customerlist in side the listbox itemssource. and as its not their then it will raise a silent error but wo't show into GUI, what you need to do is just provide the propertyname like firstname and lastname that will work.
你绑定了不是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。
well besides your binding in listbox every thing else is ok. just replace you listbox binding as like below.
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。
<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}'}" />
better to take command insteed of events.
更好地接受命令控制事件。
#4
1
Your problem is in this line of code:
你的问题出在这行代码中：
RaisePropertyChanged("CustomerList");
It doesn't work for collection add/remove events. Take a look at ObservableCollection and Item PropertyChanged.
它不适用于集合添加/删除事件。看一下ObservableCollection和Item PropertyChanged。
Keep in mind that in MVVM, you should not have much code (if any) in code behind. Consider using commands.
请记住，在MVVM中，您不应该在代码背后有太多代码（如果有的话）。考虑使用命令。
#1
3
And for the correct binding in ListBox.ItemTemplate:
并且对于ListBox.ItemTemplate中的正确绑定：
<TextBlock Text="{Binding FirstName}"
FontWeight="Bold" Foreground="Navy"/>
<TextBlock Text="{Binding LastName}"
FontWeight="Bold" Foreground="Navy"/>
The DataContext of ListBoxItem is a Customer already.
ListBoxItem的DataContext已经是Customer。
#2
3
You only create a new instance of a CustomerModel object once in your code (in the Customer View Model constructor). So you are constantly updating the same customer object rather than creating a new one.
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。
At the end of your click handler you should do a
在点击处理程序的最后，你应该做一个
viewModel.CustomerModel = new Customer();
HOWEVER
然而
Rather than having a click handler you should have an ICommand in your view model for adding a new customer. Then you should bind to command of your button to the ICommand in your view model.
您可以在视图模型中使用ICommand来添加新客户，而不是使用单击处理程序。然后，您应该将按钮的命令绑定到视图模型中的ICommand。
#3
2
you were binding the CustomerLIst.FirstName which is not walid because innterconent will check for property name customerlist in side the listbox itemssource. and as its not their then it will raise a silent error but wo't show into GUI, what you need to do is just provide the propertyname like firstname and lastname that will work.
你绑定了不是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。
well besides your binding in listbox every thing else is ok. just replace you listbox binding as like below.
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。
<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}'}" />
better to take command insteed of events.
更好地接受命令控制事件。
#4
1
Your problem is in this line of code:
你的问题出在这行代码中：
RaisePropertyChanged("CustomerList");
It doesn't work for collection add/remove events. Take a look at ObservableCollection and Item PropertyChanged.
它不适用于集合添加/删除事件。看一下ObservableCollection和Item PropertyChanged。
Keep in mind that in MVVM, you should not have much code (if any) in code behind. Consider using commands.
请记住，在MVVM中，您不应该在代码背后有太多代码（如果有的话）。考虑使用命令。