这是一个展示我遇到麻烦的行为的例子。我有一个datagrid绑定到viewmodel中的可观察记录集合。在datagrid中,我有一个DataGridTemplateColumn,它包含一个组合框,该组合框是从viewmodel中的列表中填充的。数据网格还包含文本列。窗口底部有一些文本框,用于显示记录内容。
<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" SelectionChanged="dgCustomers_SelectionChanged">
<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>
最初没有记录,因此datagrid为空,只显示包含组合框的一行。如果用户首先将数据输入到文本列中,则将记录添加到集合中,并且可以将组合框值添加到记录中。但是,如果用户首先选择组合框值,则在选择另一列时该值将消失。如果首先选择组合框数据,如何将组合框数据添加到记录中?
代码隐藏:
public partial class MainWindow : Window
{
public GridModel gridModel { get; set; }
public MainWindow()
{
InitializeComponent();
gridModel = new GridModel();
//dgCustomers.DataContext = gridModel;
this.DataContext = gridModel;
}
private void cmbCountry_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
ComboBox c = sender as ComboBox;
Debug.Print("ComboBox selection changed, index is " + c.SelectedIndex + ", selected item is " + c.SelectedItem);
}
}
记录类:
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");
}
}
}
国家/地区类:
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;
}
}
GridModel:
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");
}
}
}
转换器:
class Converters
{
}
public class SelectedRowConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return value;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value is Record)
return value;
return new Customer.Record();
}
}
ViewModelBase:
public class ViewModelBase : INotifyPropertyChanged
{
public ViewModelBase()
{
}
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string name)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(name));
}
}
}
答案 0 :(得分:2)
您看到的行为符合预期。其背后的原因是ComboBox
ItemsSource
以及SelectedItem
都绑定到Properties
Window
的{{1}} }其他列绑定到DataContext
DataGrid
。因此,当您修改下拉列表以外的列时,数据将添加到observable集合中。
您可以做的是从您需要自己添加记录的下拉列表中选择一个值后(可能通过调用ItemsSource
属性中的函数)
修改强>
根据您的代码,我制作了一个工作模型,尽可能少地对现有代码进行更改。我无法使用转换器,因为我没有类SelectedCountry
的Xaml
Customer
您的GridModel类
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="8*"/>
<RowDefinition Height="3*"/>
</Grid.RowDefinitions>
<StackPanel Grid.Row="0">
<Button HorizontalAlignment="Right" Content="Add User" Margin="0,2,2,2" Command="{Binding AddUserCommand}"/>
<DataGrid x:Name="dgCustomers"
AutoGenerateColumns="False"
ItemsSource="{Binding customers}"
SelectedItem="{Binding SelectedRow}"
SelectionUnit="FullRow"
CanUserAddRows="False">
<DataGrid.Columns>
<DataGridTemplateColumn Width="Auto" Header="Country">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<ComboBox Focusable="False"
ItemsSource="{Binding DataContext.countries, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Window}}}"
DisplayMemberPath="name"
SelectedValuePath="code"
SelectedValue="{Binding countryCode, UpdateSourceTrigger=PropertyChanged}"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<DataGridTextColumn Header="Name" Binding="{Binding name, UpdateSourceTrigger=PropertyChanged}" Width="1*"/>
<DataGridTextColumn Header="Phone" Binding="{Binding phone, UpdateSourceTrigger=PropertyChanged}" Width="1*"/>
</DataGrid.Columns>
</DataGrid>
</StackPanel>
<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>
我使用了包含public class GridModel : ViewModelBase
{
public ObservableCollection<Record> customers { get; set; }
public ObservableCollection<Country> countries
{
get;
private set;
}
public GridModel()
{
customers = new ObservableCollection<Record> { };
AddUserCommand = new RelayCommand(AddNewUser);
countries = new ObservableCollection<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 void AddNewUser()
{
customers.Add(new Record());
}
public ICommand AddUserCommand { get; set; }
private Record _selectedRow;
public Record SelectedRow
{
get
{
return _selectedRow;
}
set
{
_selectedRow = value;
Debug.Print("Datagrid selection changed");
OnPropertyChanged("SelectedRow");
}
}
}
的{{3}}工具包。您还可以定义自己的RelayCommand
实现,并使用它而不是工具包
编辑2
修正了我引入的错误,如果数据来自数据库,则会阻止组合框显示国家/地区。改进的代码不需要任何转换器