MVVM模式下做的省市区的级联效果。通过改变ComboBox执行命令改变市，区。
解决主要问题就是默认选中第一项
1.首先要定义一个属性，继承自INotifyPropertyChanged接口。我这里用的Prism框架中集成的NotificationObject
/// <summary>
/// 省
/// </summary>
private ObservableCollection<MyArea> provinceBindingList;
public ObservableCollection<MyArea> ProvinceBindingList
{
get { return provinceBindingList; }
set { provinceBindingList = value; this.RaisePropertyChanged("ProvinceBindingList"); }
}
/// <summary>
/// 市
/// </summary>
private ObservableCollection<MyArea> cityBindingList;
public ObservableCollection<MyArea> CityBindingList
{
get { return cityBindingList; }
set { cityBindingList = value; this.RaisePropertyChanged("CityBindingList"); }
}
/// <summary>
/// 区
/// </summary>
private ObservableCollection<MyArea> areaBindingList;
public ObservableCollection<MyArea> AreaBindingList
{
get { return areaBindingList; }
set { areaBindingList = value; this.RaisePropertyChanged("AreaBindingList"); }
} /// <summary>
/// 默认选择请选择项
/// </summary>
public readonly MyArea defaultSelectItem;
/// <summary>
/// 添加城市选择项
/// </summary>
private MyArea selectCity;
public MyArea SelectCity
{
get { return selectCity; }
set { selectCity = value; this.RaisePropertyChanged("SelectCity"); }
}
属性定义
2.XAML部分
<ComboBox SelectedIndex="0" ItemsSource="{Binding ProvinceBindingList,Mode=TwoWay}"
SelectedItem="{Binding defaultSelectItem,Mode=TwoWay}" DisplayMemberPath="Name"
Margin="5,105,5,5" Width="100" Name="cboProvince" Style="{StaticResource ComboBoxStyle}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="SelectionChanged">
<i:InvokeCommandAction Command="{Binding Path=DataContext.GetCity,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=ComboBox}}"
CommandParameter="{Binding Path=SelectedValue,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=ComboBox}}" />
</i:EventTrigger>
</i:Interaction.Triggers>
</ComboBox>
<ComboBox SelectedIndex="0" ItemsSource="{Binding CityBindingList,Mode=TwoWay}" DisplayMemberPath="Name"
SelectedItem="{Binding SelectCity,Mode=TwoWay}" Margin="5" Width="100" Grid.Row="1"
Name="cboCity" Style="{StaticResource ComboBoxStyle}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="SelectionChanged">
<i:InvokeCommandAction Command="{Binding Path=DataContext.GetArea,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=ComboBox}}" />
</i:EventTrigger>
</i:Interaction.Triggers>
</ComboBox>
<ComboBox SelectedIndex="0" ItemsSource="{Binding AreaBindingList,Mode=TwoWay}" DisplayMemberPath="Name"
SelectedItem="{Binding SelectCity,Mode=TwoWay}" Margin="5" Width="100" Grid.Row="2"
Name="cboArea" Style="{StaticResource ComboBoxStyle}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="SelectionChanged">
<i:InvokeCommandAction Command="{Binding Path=DataContext.GetAddCityInfoExecute,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=ComboBox}}"
CommandParameter="{Binding Path=SelectedValue,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=ComboBox}}" />
</i:EventTrigger>
</i:Interaction.Triggers>
</ComboBox>
3.命令部分
//初始化命令
this.GetProvince = new DelegateCommand(GetProvinceExecute);
this.GetCity = new DelegateCommand<MyArea>(GetCityExecute);
this.GetArea = new DelegateCommand(GetAreaExecute);
/// <summary>
/// 获取省
/// </summary>
private void GetProvinceExecute()
{
var province = AreaManager.GetProvince();
province.Insert(, defaultSelectItem);
ProvinceBindingList = new ObservableCollection<MyArea>(province);
} /// <summary>
/// 获取市
/// </summary>
/// <param name="obj"></param>
private void GetAreaExecute()
{
if (SelectCity != null && SelectCity.ID != "")
{
var area = AreaManager.GetAreaByCID(SelectCity);
area.Insert(, defaultSelectItem);
AreaBindingList = new ObservableCollection<MyArea>(area);
}
else if (SelectCity == null || SelectCity != null && SelectCity.ID == "")
AreaBindingList = new ObservableCollection<MyArea>(new List<MyArea>() { defaultSelectItem });
} /// <summary>
/// 获取区
/// </summary>
/// <param name="obj"></param>
private void GetCityExecute(MyArea province)
{
if (province != null && province.ID != "")
{
var city = AreaManager.GetCityByPID(province);
city.Insert(, defaultSelectItem);
CityBindingList = new ObservableCollection<MyArea>(city);
SelectCity = defaultSelectItem;
}
else if (province == null || province != null && province.ID == "")
CityBindingList = new ObservableCollection<MyArea>(new List<MyArea>() { defaultSelectItem });
}
命令对应方法