当我设置我的ViewModel的属性时（我指的是实现INotifyPropertyChanged并且是视图的DataContext的类），OnPropertyChange被调用，但它只是跳过“handler（this，new PropertyChangedEventArgs（name）） “因为PropertyChanged为null，因此UI没有更新。下面是我的代码：
XAML：
<Window x:Class="Magic_Vehicle_Portal_MVVM.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:Magic_Vehicle_Portal_MVVM"
xmlns:vehicle="clr-namespace:Magic_Vehicle_Portal_MVVM.Vehicle"
Title="MainWindow" Height="600" Width="800"
>
<Grid >
<Grid.DataContext>
<vehicle:VehicleBase />
</Grid.DataContext>
<Grid.Resources>
<Style x:Key="textBlockStyle"
TargetType="TextBlock">
<Setter Property="VerticalAlignment"
Value="Center" />
</Style>
<Style x:Key="textBoxStyle"
TargetType="TextBox">
<Setter Property="VerticalAlignment"
Value="Center" />
<Setter Property="HorizontalAlignment"
Value="Left" />
<Setter Property="Height"
Value="22" />
<Setter Property="Width"
Value="200" />
</Style>
<Style x:Key="comboBoxStyle"
TargetType="ComboBox">
<Setter Property="VerticalAlignment"
Value="Center" />
<Setter Property="HorizontalAlignment"
Value="Left" />
<Setter Property="Height"
Value="22" />
<Setter Property="Width"
Value="200" />
</Style>
<Style x:Key="datePickerStyle"
TargetType="DatePicker">
<Setter Property="VerticalAlignment"
Value="Center" />
<Setter Property="HorizontalAlignment"
Value="Left" />
<!--<Setter Property=""
Value="" />-->
<Setter Property="Height"
Value="24" />
<Setter Property="Width"
Value="200" />
</Style>
</Grid.Resources>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="30" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Grid Grid.Row="0">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="2*" />
<ColumnDefinition Width="2*" />
<ColumnDefinition Width="160" />
</Grid.ColumnDefinitions>
<TextBlock Grid.Column="0"
Style="{StaticResource ResourceKey=textBlockStyle}"
Text="Product Type"
Margin="10,2,0,0"/>
<ComboBox Grid.Column="1"
Name="prodcutTypeTextblock"
Style="{StaticResource ResourceKey=comboBoxStyle}"
Margin="10,2,0,0"
ItemsSource="{Binding Path=Product_Type_List}"
Text="{Binding Path=Product_Type}" />
<TextBox Grid.Column="2"
Name="searchKeyWordBox"
Style="{StaticResource ResourceKey=textBoxStyle}"
HorizontalAlignment="Right"/>
<Button Grid.Column="3"
Content="Search"
Width="120"
Height="22"
Margin="10,2,0,2"
HorizontalAlignment="Left"
Click="Search_Click"
IsDefault="True" />
</Grid>
<Grid Grid.Row="1">
<Grid.RowDefinitions>
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="40" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="20" />
<ColumnDefinition Width="120" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="120" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="20" />
</Grid.ColumnDefinitions>
<TextBlock Grid.Column="1"
Grid.Row="0"
Text="Name"
Style="{StaticResource ResourceKey=textBlockStyle}"
FontWeight="Bold" />
<TextBox Grid.Column="2"
Grid.ColumnSpan="3"
Grid.Row="0"
Width="565"
Style="{StaticResource ResourceKey=textBoxStyle}"
Text="{Binding Path=Vehicle_Name}" />
<TextBlock Grid.Column="1"
Grid.Row="1"
Text="Onshore"
Style="{StaticResource ResourceKey=textBlockStyle}" />
<CheckBox Grid.Column="2"
Grid.Row="1"
Content=""
VerticalAlignment="Center"
HorizontalAlignment="Left" />
<TextBlock Grid.Column="1"
Grid.Row="2"
Text="Currency"
Style="{StaticResource ResourceKey=textBlockStyle}" />
<ComboBox Grid.Column="2"
Grid.Row="2"
Style="{StaticResource ResourceKey=comboBoxStyle}"
ItemsSource="{Binding Path=Currency_List}"
SelectedItem="{Binding Path=Currency}" />
<TextBlock Grid.Column="1"
Grid.Row="3"
Text="CUSIP"
Style="{StaticResource ResourceKey=textBlockStyle}" />
<TextBox Grid.Column="2"
Grid.Row="3"
Style="{StaticResource ResourceKey=textBoxStyle}"
Text="{Binding Path=CUSIP}" />
<TextBlock Grid.Column="1"
Grid.Row="4"
Text="ISIN"
Style="{StaticResource ResourceKey=textBlockStyle}" />
<TextBox Grid.Column="2"
Grid.Row="4"
Style="{StaticResource ResourceKey=textBoxStyle}"
Text="{Binding Path=ISIN}" />
<TextBlock Grid.Column="1"
Grid.Row="5"
Text="Ticker"
Style="{StaticResource ResourceKey=textBlockStyle}" />
<TextBox Grid.Column="2"
Grid.Row="5"
Style="{StaticResource ResourceKey=textBoxStyle}"
Text="{Binding Path=Ticker}" />
<TextBlock Grid.Column="1"
Grid.Row="6"
Text="Valoren"
Style="{StaticResource ResourceKey=textBlockStyle}" />
<TextBox Grid.Column="2"
Grid.Row="6"
Style="{StaticResource ResourceKey=textBoxStyle}"
Text="{Binding Path=Valoren}" />
<TextBlock Grid.Column="1"
Grid.Row="7"
Text="SAC Class"
Style="{StaticResource ResourceKey=textBlockStyle}" />
<ComboBox Grid.Column="2"
Grid.Row="7"
Style="{StaticResource ResourceKey=comboBoxStyle}" />
<TextBlock Grid.Column="1"
Grid.Row="8"
Text="PC Class"
Style="{StaticResource ResourceKey=textBlockStyle}" />
<ComboBox Grid.Column="2"
Grid.Row="8"
Style="{StaticResource ResourceKey=comboBoxStyle}"
ItemsSource="{Binding Path=PC_Class_List}"
SelectedItem="{Binding Path=PC_Class}" />
<TextBlock Grid.Column="1"
Grid.Row="9"
Text="Implementation Type"
Style="{StaticResource ResourceKey=textBlockStyle}" />
<ComboBox Grid.Column="2"
Grid.Row="9"
Style="{StaticResource ResourceKey=comboBoxStyle}"
ItemsSource="{Binding Path=Implementation_Type_List}"
SelectedItem="{Binding Path=Implementation_Type}" />
<ContentControl Grid.Row="1"
</Grid>
</Grid>
</Grid>
主窗口：
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private VehicleBase _selected_vehicle = new VehicleBase();
public VehicleBase Selected_Vehicle
{
get
{
return _selected_vehicle;
}
set
{
_selected_vehicle = value;
}
}
private void Search_Click(object sender, RoutedEventArgs e)
{
string keyword = searchKeyWordBox.Text;
//int vehicle_id;
string query;
DataView dv;
query = string.Format("select * from dbo.vehicle_attributes where vehicle_id = '{0}'",keyword);
dv = Utility.DAL.ExecuteQuery(query);
Selected_Vehicle.Vehicle_Name = dv[0]["vehicle_name"].ToString();
Selected_Vehicle.OnPropertyChanged("Vehicle_Name");
//vehicleSearchResults.ItemsSource = dv;
//statusTextBlock.Text = string.Format("{0} Vehicle(s) Found", dv.Count);
}
}
视图模型：
public class VehicleBase: INotifyPropertyChanged
{
public VehicleBase()
{
//Product_Type = product_type;
SetLists();
Product_Type = "Structure";
}
private void SetLists()
{
SetList_Product_Type();
SetList_Currency();
SetList_PC_Class();
}
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string name)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(name));
}
}
//ProductType
private List<string> _product_Type_List = new List<string>();
public List<string> Product_Type_List
{
get
{
return _product_Type_List;
}
set
{
_product_Type_List = value;
OnPropertyChanged("Product_Type_List");
}
}
private void SetList_Product_Type()
{
string query = "SELECT * FROM dbo.product_types WHERE is_enabled = 1";
DataView dv = Utility.DAL.ExecuteQuery(query);
List<string> l = new List<string>();
for (int i = 0; i < dv.Count; i++)
{
l.Add(dv[i]["product_type_name"].ToString());
}
Product_Type_List = l;
}
private string _product_type;
public string Product_Type
{
get
{
return _product_type;
}
set
{
_product_type = value;
OnPropertyChanged("Product_Type");
}
}
// Vehicle Name
private string _vehicle_Name;
public string Vehicle_Name
{
get
{
return _vehicle_Name;
}
set
{
_vehicle_Name = value;
OnPropertyChanged("Vehicle_Name");
}
}
}
视图模型：
<!-- language: c# -->
public class VehicleBase: INotifyPropertyChanged
{
public VehicleBase()
{
//Product_Type = product_type;
SetLists();
Product_Type = "Structure";
}
private void SetLists()
{
SetList_Product_Type();
SetList_Currency();
SetList_PC_Class();
}
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string name)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(name));
}
}
//ProductType
private List<string> _product_Type_List = new List<string>();
public List<string> Product_Type_List
{
get
{
return _product_Type_List;
}
set
{
_product_Type_List = value;
OnPropertyChanged("Product_Type_List");
}
}
private void SetList_Product_Type()
{
string query = "SELECT * FROM dbo.product_types WHERE is_enabled = 1";
DataView dv = Utility.DAL.ExecuteQuery(query);
List<string> l = new List<string>();
for (int i = 0; i < dv.Count; i++)
{
l.Add(dv[i]["product_type_name"].ToString());
}
Product_Type_List = l;
}
private string _product_type;
public string Product_Type
{
get
{
return _product_type;
}
set
{
_product_type = value;
OnPropertyChanged("Product_Type");
}
}
// Vehicle Name
private string _vehicle_Name;
public string Vehicle_Name
{
get
{
return _vehicle_Name;
}
set
{
_vehicle_Name = value;
OnPropertyChanged("Vehicle_Name");
}
}
}
答案 0 :(得分：1)
再观察一次。使用observablecollection而不是List，因为List没有实现INotifyPropertyChanged，因此当您添加新项时，它不会反映在UI中，因为observablecollection实现了INotifyPropertyChanged
请参阅以下链接
http://www.c-sharpcorner.com/UploadFile/1a81c5/a-simple-wpf-application-implementing-mvvm/
http://www.c-sharpcorner.com/UploadFile/e06010/wpf-icommand-in-mvvm/
答案 1 :(得分：0)
您可以在MainWindow.Xaml.cs中更改此类内容，如下所示
private VehicleBase _selected_vehicle = new VehicleBase();
public MainWindow()
{
InitializeComponent();
DataContext=_selected_vehicle;
}
并保留剩余的代码，不需要进行任何更改。从Xmal文件中重新创建DataContext。这将解决您的问题，无需将Viewmodel设为SingleTon。
或者如果你只想将dataContext设置为网格，那么你可以给网格命名为grid1并将dataContext设置为如下，而不是设置为整个窗口
public MainWindow()
{
InitializeComponent();
grid1.DataContext=_selected_vehicle;
}