代码之家 › 专栏 › 技术社区 › xanadont

将组合框双向绑定到简单字符串数组

data-binding silverlight

xanadont · 技术社区 · 14 年前

我有一个简单的类,它提供如下状态代码:

public class StateProvider
{
    static string[] _codes = new string[]
    {
        "AL",
        "AK",
        ...
    };

    public string[] GetAll()
    {
        return _codes;
    }
}

我的支持视图的模型类看起来有点像这样:

public class ProjectModel : ChangeNotifier
{
    StateProvider _states = new StateProvider();

    public ProjectModel()
    {
        Project = LoadProject();
    }

    ProjectEntity _project;
    public ProjectEntity Project
    {
        get { return _project; }

        set
        {
            _project = value;
            FirePropertyChanged("Project");
        }
    }

    public string[] States { get { return _states.GetAll(); } }
}

<ComboBox SelectedValue="{Binding Project.State, Mode=TwoWay}" SelectedValuePath="{Binding RelativeSource={RelativeSource Self}}" ItemsSource="{Binding States}" />

我希望这非常简单,因为我想显示州代码和保存州代码(我不想显示完整的州名称)。因此,我不想在创建一个具有Code和FullName属性的State类时遇到麻烦,避免使用combobox的SelectedValuePath和displaymberpath属性。

编辑: 在代码中添加了ProjectModel如何更改通知。请注意,ProjectEntity类也会这样做。相信我,这很管用。我省略了它,因为它还继承了一个实体基类,该实体基类通过反射更改通知。双向绑定对任何东西都有效,但对组合框无效。

3 回复 | 直到 14 年前

iCollect.it Ltd 14 年前

您必须至少在ProjectModel类上实现IPropertyNotifyChanged

public class ProjectModel : INotifyPropertyChanged
{
        public event PropertyChangedEventHandler PropertyChanged;

public ProjectEntity Project
{
    get { return (ProjectEntity)GetValue(ProjectProperty); }
    set { SetValue(ProjectProperty, value); }
}

// Using a DependencyProperty as the backing store for Project.  
// This enables animation, styling, binding, etc...
public static readonly DependencyProperty ProjectProperty =
    DependencyProperty.Register("Project",
                                typeof(ProjectEntity),
                                typeof(ProjectModel),
                                new PropertyMetadata(null,
                                    new PropertyChangedCallback(OnProjectChanged)));

static void OnProjectChanged(object sender, DependencyPropertyChangedEventArgs args)
{
    // If you need to handle changes
}

xanadont 12 年前

哇,谁想到会变成这样:

<ComboBox ItemsSource="{Binding States}" SelectedValue="{Binding Project.State, Mode=TwoWay}" />

结果是我在XAML中放置属性的顺序。SelectedValue绑定发生在ItemsSource绑定之前,因此绑定SelectedValue时组合框中没有任何项。

Yogesh 14 年前

将ProjectModel类更改为:

public class ProjectModel : ChangeNotifier
{
    StateProvider _states = new StateProvider();

    public ProjectModel()
    {
        Project = LoadProject();

        States = new ObservableCollection<string>(_states.GetAll());
    }

    ProjectEntity _project;
    public ProjectEntity Project
    {
        get { return _project; }

        set
        {
            _project = value;
            FirePropertyChanged("Project");
        }
    }

    public ObservableCollection<string> States { get; set; }
}

还要确保 ProjectEntity INotifyPropertyChanged