<强度 > 问题摘要

当使用 2 个堆叠组合框时, 子组合框不选择当前项目, 而不是空项( 我不知道它是从哪里来的!) 被选中 。

<强度 > 问题细节

我以 xaml 中声明了两个组合框, 如下所示 。 正在玩的两个实体是 < 坚固 > StandardRack < / 坚固 > 和 < 坚固 > RelayConfig

<强>XAML:

<ComboBox ItemsSource="{Binding StandardRacks}" DisplayMemberPath="Name"
          SelectedItem="{Binding StandardRack, Mode=TwoWay}"  SelectedValuePath="Id"

<ComboBox ItemsSource="{Binding RelayConfigs}" DisplayMemberPath="DisplayName" 
          SelectedValue="{Binding DefaultRelayConfig, Mode=TwoWay}" SelectedValuePath="Id"

以下是支持属性, 以及在 ViewModel 中装入组合框的代码

< 强度 > ViewModel

private ObservableCollection<StandardRack> _standardRacks;
public ObservableCollection<StandardRack> StandardRacks {
    get { return _standardRacks; }
    set { _standardRacks = value; RaisePropertyChanged(() => StandardRacks); }
}

private StandardRack _standardRack;
public StandardRack StandardRack {
    get { return _standardRack; }
    set {
        if (_standardRack != value) {
            _standardRack = value;
            LoadRelayConfigs();
            RaisePropertyChanged(() => StandardRack);
        }
    }
}

private ObservableCollection<RelayConfig> _relayConfigs;
public ObservableCollection<RelayConfig> RelayConfigs {
    get { return _relayConfigs; }
    set { _relayConfigs = value; RaisePropertyChanged(() => RelayConfigs); }
}

private RelayConfig _defaultRelayConfig;
public RelayConfig DefaultRelayConfig {
    get { return _defaultRelayConfig; }
    set { _defaultRelayConfig = value; RaisePropertyChanged(() => DefaultRelayConfig); }
}

private void LoadRack() {
    StandardRacks = new ObservableCollection<StandardRack>(
                    unitOfWork.StandardRackRepository.GetQueryable().Include(sr => sr.StandardRelay).ToList());
    if (StandardRacks.Count > 0) {
        StandardRack = Rack.StandardRack; //Set the current value of StandardRacks combobox
    }
}

//Loads RelayConfigs Combobox based on Current Value of StandardRacks Combobox

private void LoadRelayConfigs() {
    RelayConfigs = new ObservableCollection<RelayConfig>(
        unitOfWork.RelayConfigRepository.GetQueryable()
        .Where(rc => rc.StandardRelays.Any(srl => srl.Id == StandardRack.StandardRelay.Id)).ToList());
    DefaultRelayConfig = Rack.DefaultRelayConfig; //Set Current Value of RelayConfigs Combobox. Does not work.
}

上述代码正确装入组合框( StandardRacks 和 RelayConfigs) 的项目。 但是, 中继 Configs 选中的值没有被设定为 XAML 指向的值。 相反, 我得到一个空项作为当前项目在 RelayConfigs 组合框中 。