C# DataGrid中的WPF组合框
这是一个显示我有问题的行为的例子。我有一个datagrid，它绑定到viewmodel中可观察到的记录集合。在datagrid中，我有一个DataGridTemplateColumn，其中包含一个组合框，该组合框是从viewmodel中的列表填充的。datagrid还包含文本列。窗口底部有一些文本框显示记录内容C# DataGrid中的WPF组合框,c#,wpf,mvvm,combobox,datagrid,C#,Wpf,Mvvm,Combobox,Datagrid,这是一个显示我有问题的行为的例子。我有一个datagrid，它绑定到viewmodel中可观察到的记录集合。在datagrid中，我有一个DataGridTemplateColumn，其中包含一个组合框，该组合框是从viewmodel中的列表填充的。datagrid还包含文本列。窗口底部有一些文本框显示记录内容 <Window x:Class="Customer.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/x
<Window x:Class="Customer.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:Customer"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<local:SelectedRowConverter x:Key="selectedRowConverter"/>
</Window.Resources>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="8*"/>
<RowDefinition Height="3*"/>
</Grid.RowDefinitions>
<DataGrid x:Name="dgCustomers" AutoGenerateColumns="False"
ItemsSource="{Binding customers}" SelectedItem="{Binding SelectedRow,
Converter={StaticResource selectedRowConverter}, Mode=TwoWay}"
CanUserAddRows="True" Grid.Row="0" >
<DataGrid.Columns>
<DataGridTemplateColumn Width="Auto" Header="Country">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<ComboBox x:Name="cmbCountry" ItemsSource="{Binding DataContext.countries,
RelativeSource={RelativeSource AncestorType={x:Type Window}}}"
DisplayMemberPath="name" SelectedValuePath="name" Margin="5"
SelectedItem="{Binding DataContext.SelectedCountry,
RelativeSource={RelativeSource AncestorType={x:Type Window}}, Mode=TwoWay,
UpdateSourceTrigger=PropertyChanged}" SelectionChanged="cmbCountry_SelectionChanged" />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<DataGridTextColumn Header="Name" Binding="{Binding name}" Width="1*"/>
<DataGridTextColumn Header="Phone" Binding="{Binding phone}" Width="1*"/>
</DataGrid.Columns>
</DataGrid>
<Grid x:Name="grdDisplay" DataContext="{Binding ElementName=dgCustomers}" Grid.Row="1">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*"/>
<ColumnDefinition Width="1*"/>
<ColumnDefinition Width="1*"/>
</Grid.ColumnDefinitions>
<Label Grid.Column="2" Content="Country:" VerticalAlignment="Center" HorizontalAlignment="Right"/>
<Label Grid.Column="4" Content="Code:" VerticalAlignment="Center" HorizontalAlignment="Right"/>
<BulletDecorator Grid.Column="0">
<BulletDecorator.Bullet>
<Label Content="Name:" VerticalAlignment="Center" HorizontalAlignment="Right"/>
</BulletDecorator.Bullet>
<TextBox x:Name="txtId" Text="{Binding ElementName=dgCustomers, Path=SelectedItem.name}" Margin="5,5,5,5"/>
</BulletDecorator>
<BulletDecorator Grid.Column="1">
<BulletDecorator.Bullet>
<Label Content="Code:" VerticalAlignment="Center" HorizontalAlignment="Right"/>
</BulletDecorator.Bullet>
<TextBox x:Name="txtCode" Text="{Binding ElementName=dgCustomers, Path=SelectedItem.countryCode}" Margin="5,5,5,5"/>
</BulletDecorator>
<BulletDecorator Grid.Column="2">
<BulletDecorator.Bullet>
<Label Content="Phone:" VerticalAlignment="Center" HorizontalAlignment="Right"/>
</BulletDecorator.Bullet>
<TextBox x:Name="txtPhone" Text="{Binding ElementName=dgCustomers, Path=SelectedItem.phone}" Margin="5,5,5,5"/>
</BulletDecorator>
</Grid>
</Grid>
</Window>
public class Record : ViewModelBase
{
private string _name;
public string name
{
get { return _name; }
set
{
_name = value;
OnPropertyChanged("name");
}
}
private string _phone;
public string phone
{
get { return _phone; }
set
{
_phone = value;
OnPropertyChanged("phone");
}
}
private int _countryCode;
public int countryCode
{
get { return _countryCode; }
set
{
_countryCode = value;
OnPropertyChanged("countryCode");
}
}
}
public class Country : ViewModelBase
{
private string _name;
public string name
{
get { return _name; }
set
{
_name = value;
OnPropertyChanged("name");
}
}
private int _id;
public int id
{
get { return _id; }
set
{
_id = value;
OnPropertyChanged("id");
}
}
private int _code;
public int code
{
get { return _code; }
set
{
_code = value;
OnPropertyChanged("code");
}
}
public override string ToString()
{
return _name;
}
}
public class GridModel : ViewModelBase
{
public ObservableCollection<Record> customers { get; set; }
public List<Country> countries { get; set; }
public GridModel()
{
customers = new ObservableCollection<Record>();
countries = new List<Country> { new Country { id = 1, name = "England", code = 44 }, new Country { id = 2, name = "Germany", code = 49 },
new Country { id = 3, name = "US", code = 1}, new Country { id = 4, name = "Canada", code = 11 }};
}
private Country _selectedCountry;
public Country SelectedCountry
{
get
{
return _selectedCountry;
}
set
{
_selectedCountry = value;
_selectedRow.countryCode = _selectedCountry.code;
OnPropertyChanged("SelectedRow");
}
}
private Record _selectedRow;
public Record SelectedRow
{
get
{
return _selectedRow;
}
set
{
_selectedRow = value;
Debug.Print("Datagrid selection changed");
OnPropertyChanged("SelectedRow");
}
}
}
public class ViewModelBase : INotifyPropertyChanged
{
public ViewModelBase()
{
}
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string name)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(name));
}
}
}
<local:BindingProxy x:Key="CountryProxy" Data="{Binding}" />
<TextBox x:Name="txtCode" Text="{Binding Path=record.countryCode}" Margin="5,5,5,5"/>
这消除了错误40，但我仍然没有在文本框中看到任何东西。你能告诉我出了什么问题吗？请原谅我的诚实，但这段代码有很多问题 首先，有一些严重的偏差 来自MVVM。MVVM是一个分层架构…首先是模型，然后是视图模型，然后是视图模型。从技术上讲，转换器是视图的一部分，但如果有的话，它们位于视图的另一侧，而不是视图模型。您所做的是使用转换器在您的模型中生成新记录：
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value is Record)
return value;
return new Customer.Record(); <<<<<<<< this here
}
// record model
public class Record
{
public string name {get; set;}
public string phone { get; set; }
public int countryCode {get; set;}
}
// record view model
public class RecordViewModel : ViewModelBase
{
private Record record = new Record();
public string name
{
get { return record.name; }
set
{
record.name = value;
RaisePropertyChanged("name");
}
}
public string phone
{
get { return record.phone; }
set
{
record.phone = value;
RaisePropertyChanged("phone");
}
}
private Country _country;
public Country country
{
get { return _country; }
set
{
_country = value;
record.countryCode = value.code;
RaisePropertyChanged("country");
}
}
}
public class Country : ViewModelBase
{
private string _name;
public string name
{
get { return _name; }
set
{
_name = value;
RaisePropertyChanged("name");
}
}
private int _id;
public int id
{
get { return _id; }
set
{
_id = value;
RaisePropertyChanged("id");
}
}
private int _code;
public int code
{
get { return _code; }
set
{
_code = value;
RaisePropertyChanged("code");
}
}
public override string ToString()
{
return _name;
}
}
public class GridModel : ViewModelBase
{
public ObservableCollection<RecordViewModel> customers { get; set; }
public List<Country> countries { get; set; }
public GridModel()
{
customers = new ObservableCollection<RecordViewModel>();
countries = new List<Country> { new Country { id = 1, name = "England", code = 44 }, new Country { id = 2, name = "Germany", code = 49 },
new Country { id = 3, name = "US", code = 1}, new Country { id = 4, name = "Canada", code = 11 }};
}
private RecordViewModel _selectedRow;
public RecordViewModel SelectedRow
{
get
{
return _selectedRow;
}
set
{
_selectedRow = value;
Debug.Print("Datagrid selection changed");
RaisePropertyChanged("SelectedRow");
}
}
}
// this is needed for when you need to bind something that isn't part of the visual tree (i.e. your combobox dropdowns)
// see http://www.thomaslevesque.com/2011/03/21/wpf-how-to-bind-to-data-when-the-datacontext-is-not-inherited/ for details
public class BindingProxy : Freezable
{
#region Overrides of Freezable
protected override Freezable CreateInstanceCore()
{
return new BindingProxy();
}
#endregion
public object Data
{
get { return (object)GetValue(DataProperty); }
set { SetValue(DataProperty, value); }
}
// Using a DependencyProperty as the backing store for Data. This enables animation, styling, binding, etc...
public static readonly DependencyProperty DataProperty =
DependencyProperty.Register("Data", typeof(object), typeof(BindingProxy), new UIPropertyMetadata(null));
}
<Window.Resources>
<local:BindingProxy x:Key="CountryProxy" Data="{Binding Path=countries}" />
</Window.Resources>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="8*"/>
<RowDefinition Height="3*"/>
</Grid.RowDefinitions>
<DataGrid x:Name="dgCustomers" AutoGenerateColumns="False"
ItemsSource="{Binding customers}" SelectedItem="{Binding SelectedRow, Mode=TwoWay}"
CanUserAddRows="True" Grid.Row="0" >
<DataGrid.Columns>
<DataGridComboBoxColumn Header="Country"
ItemsSource="{Binding Source={StaticResource ResourceKey=CountryProxy}, Path=Data}" DisplayMemberPath="name"
SelectedItemBinding="{Binding country, UpdateSourceTrigger=PropertyChanged}" />
<DataGridTextColumn Header="Name" Binding="{Binding name, UpdateSourceTrigger=PropertyChanged}" Width="1*" />
<DataGridTextColumn Header="Phone" Binding="{Binding phone, UpdateSourceTrigger=PropertyChanged}" Width="1*"/>
</DataGrid.Columns>
</DataGrid>
<Grid x:Name="grdDisplay" Grid.Row="1">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*"/>
<ColumnDefinition Width="1*"/>
<ColumnDefinition Width="1*"/>
</Grid.ColumnDefinitions>
<Label Grid.Column="2" Content="Country:" VerticalAlignment="Center" HorizontalAlignment="Right"/>
<Label Grid.Column="4" Content="Code:" VerticalAlignment="Center" HorizontalAlignment="Right"/>
<BulletDecorator Grid.Column="0">
<BulletDecorator.Bullet>
<Label Content="Name:" VerticalAlignment="Center" HorizontalAlignment="Right"/>
</BulletDecorator.Bullet>
<TextBox x:Name="txtId" Text="{Binding Path=SelectedRow.name}" Margin="5,5,5,5"/>
</BulletDecorator>
<BulletDecorator Grid.Column="1">
<BulletDecorator.Bullet>
<Label Content="Code:" VerticalAlignment="Center" HorizontalAlignment="Right"/>
</BulletDecorator.Bullet>
<TextBox x:Name="txtCode" Text="{Binding Path=SelectedRow.country.code}" Margin="5,5,5,5"/>
</BulletDecorator>
<BulletDecorator Grid.Column="2">
<BulletDecorator.Bullet>
<Label Content="Phone:" VerticalAlignment="Center" HorizontalAlignment="Right"/>
</BulletDecorator.Bullet>
<TextBox x:Name="txtPhone" Text="{Binding Path=SelectedRow.phone}" Margin="5,5,5,5"/>
</BulletDecorator>
</Grid>
</Grid>
忘记转换器吧，你不需要它。这段代码引入的一个问题是，您现在需要单击组合框两次：首先选择行，然后再次编辑它。但是网络上有很多地方展示了如何解决这个问题，所以我将把它留给你。任何批评都是非常有建设性的：我正在运行你发送的代码，但我仍然没有在窗口底部的文本框中看到countryCode。输出窗口中有几个错误；我已经编辑了问题以添加它们。抱歉，国家代码的绑定不正确，我在上面的XAML中修复了它。我注意到的另一件事是，底部的字段直接绑定到元素。虽然这通常是可行的，但是如果您绑定到视图模型字段，您会发现以后的问题会少一些，我现在将代码改为这样做，特别是当您开始移动XAML或需要在代码中放置断点以确保控件正常工作时。最后一件事…底部的国家代码编辑字段当前正确显示国家代码，但编辑它不会传播回记录，这基本上是在datagrid中使用组合框的副作用，但下面是国家代码。如果确实需要此功能，则需要将countryCode字段添加到视图模型中。这就提出了一个问题，视图模型首先是如何获得国家的数组的……这可以通过让GridModel监视新的RecordViewModels被添加到ObservableCollection并在创建时初始化它们来实现。doh……RecordViewModel的国家设置器中也有一个小错误：我在打电话RaisePropertyChanged在countryCode上而不是在country上。它可以工作！太棒了，谢谢你，马克。底部的那些框只是为了让我能够看到发生了什么，它们没有出现在我的实际应用程序中。还感谢您为我设置了正确的MVVM实现路径：
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value is Record)
return value;
return new Customer.Record(); <<<<<<<< this here
}
// record model
public class Record
{
public string name {get; set;}
public string phone { get; set; }
public int countryCode {get; set;}
}
// record view model
public class RecordViewModel : ViewModelBase
{
private Record record = new Record();
public string name
{
get { return record.name; }
set
{
record.name = value;
RaisePropertyChanged("name");
}
}
public string phone
{
get { return record.phone; }
set
{
record.phone = value;
RaisePropertyChanged("phone");
}
}
private Country _country;
public Country country
{
get { return _country; }
set
{
_country = value;
record.countryCode = value.code;
RaisePropertyChanged("country");
}
}
}
public class Country : ViewModelBase
{
private string _name;
public string name
{
get { return _name; }
set
{
_name = value;
RaisePropertyChanged("name");
}
}
private int _id;
public int id
{
get { return _id; }
set
{
_id = value;
RaisePropertyChanged("id");
}
}
private int _code;
public int code
{
get { return _code; }
set
{
_code = value;
RaisePropertyChanged("code");
}
}
public override string ToString()
{
return _name;
}
}
public class GridModel : ViewModelBase
{
public ObservableCollection<RecordViewModel> customers { get; set; }
public List<Country> countries { get; set; }
public GridModel()
{
customers = new ObservableCollection<RecordViewModel>();
countries = new List<Country> { new Country { id = 1, name = "England", code = 44 }, new Country { id = 2, name = "Germany", code = 49 },
new Country { id = 3, name = "US", code = 1}, new Country { id = 4, name = "Canada", code = 11 }};
}
private RecordViewModel _selectedRow;
public RecordViewModel SelectedRow
{
get
{
return _selectedRow;
}
set
{
_selectedRow = value;
Debug.Print("Datagrid selection changed");
RaisePropertyChanged("SelectedRow");
}
}
}
// this is needed for when you need to bind something that isn't part of the visual tree (i.e. your combobox dropdowns)
// see http://www.thomaslevesque.com/2011/03/21/wpf-how-to-bind-to-data-when-the-datacontext-is-not-inherited/ for details
public class BindingProxy : Freezable
{
#region Overrides of Freezable
protected override Freezable CreateInstanceCore()
{
return new BindingProxy();
}
#endregion
public object Data
{
get { return (object)GetValue(DataProperty); }
set { SetValue(DataProperty, value); }
}
// Using a DependencyProperty as the backing store for Data. This enables animation, styling, binding, etc...
public static readonly DependencyProperty DataProperty =
DependencyProperty.Register("Data", typeof(object), typeof(BindingProxy), new UIPropertyMetadata(null));
}
<Window.Resources>
<local:BindingProxy x:Key="CountryProxy" Data="{Binding Path=countries}" />
</Window.Resources>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="8*"/>
<RowDefinition Height="3*"/>
</Grid.RowDefinitions>
<DataGrid x:Name="dgCustomers" AutoGenerateColumns="False"
ItemsSource="{Binding customers}" SelectedItem="{Binding SelectedRow, Mode=TwoWay}"
CanUserAddRows="True" Grid.Row="0" >
<DataGrid.Columns>
<DataGridComboBoxColumn Header="Country"
ItemsSource="{Binding Source={StaticResource ResourceKey=CountryProxy}, Path=Data}" DisplayMemberPath="name"
SelectedItemBinding="{Binding country, UpdateSourceTrigger=PropertyChanged}" />
<DataGridTextColumn Header="Name" Binding="{Binding name, UpdateSourceTrigger=PropertyChanged}" Width="1*" />
<DataGridTextColumn Header="Phone" Binding="{Binding phone, UpdateSourceTrigger=PropertyChanged}" Width="1*"/>
</DataGrid.Columns>
</DataGrid>
<Grid x:Name="grdDisplay" Grid.Row="1">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*"/>
<ColumnDefinition Width="1*"/>
<ColumnDefinition Width="1*"/>
</Grid.ColumnDefinitions>
<Label Grid.Column="2" Content="Country:" VerticalAlignment="Center" HorizontalAlignment="Right"/>
<Label Grid.Column="4" Content="Code:" VerticalAlignment="Center" HorizontalAlignment="Right"/>
<BulletDecorator Grid.Column="0">
<BulletDecorator.Bullet>
<Label Content="Name:" VerticalAlignment="Center" HorizontalAlignment="Right"/>
</BulletDecorator.Bullet>
<TextBox x:Name="txtId" Text="{Binding Path=SelectedRow.name}" Margin="5,5,5,5"/>
</BulletDecorator>
<BulletDecorator Grid.Column="1">
<BulletDecorator.Bullet>
<Label Content="Code:" VerticalAlignment="Center" HorizontalAlignment="Right"/>
</BulletDecorator.Bullet>
<TextBox x:Name="txtCode" Text="{Binding Path=SelectedRow.country.code}" Margin="5,5,5,5"/>
</BulletDecorator>
<BulletDecorator Grid.Column="2">
<BulletDecorator.Bullet>
<Label Content="Phone:" VerticalAlignment="Center" HorizontalAlignment="Right"/>
</BulletDecorator.Bullet>
<TextBox x:Name="txtPhone" Text="{Binding Path=SelectedRow.phone}" Margin="5,5,5,5"/>
</BulletDecorator>
</Grid>
</Grid>