Question

问题摘要

当使用2个级联组合框时，子组合框不会选择当前项目，而是选择空项目（我不知道它来自哪里！）。

问题详情

我在xaml中声明了两个组合框，如下所示。游戏中的两个实体是 StandardRack 和 RelayConfig

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中加载组合框的代码

视图模型

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.
}

上面的代码正确加载了组合框（StandardRacks和RelayConfigs）。但是，RelayConfigs选择的值未设置为它从XAML指向的值。相反，我在RelayConfigs组合框中得到一个空项目作为当前项目。

Answer 1

'RelayConfigs'选择中的'DefaultRelayConfig'部分是什么？

级联两个组合框 - Child Combobox不选择当前值

1 个答案: