Silverlight 4 数据模板数据类型

发布于 2024-09-07 23:46:23 字数 910 浏览 3 评论 0原文

Silverlight 4 已经发布了,我们似乎再次错过了这个版本中的 DataTemplate DataType 功能,恕我直言,这对于 MVVM 支持非常关键。对于我的 WPF 应用程序,此时,我非常习惯将视图的 DataTemplates 全局添加到我的 Application.Resources 以及相应 ViewModel 的 DataTypes:

即。

<DataTemplate DataType="{x:Type viewModels:myViewModel}">
<views:myView/>
</DataTemplate>

我喜欢这种方法,因为我所有绑定的 ViewModel 都会自动显示正确的内容...当我的视图中有一些 ItemSource 绑定到 ViewModel 集合时特别有用...例如,这将自动确保绑定到 Collection 的 TabControl 显示与 SomeViewModel 关联的视图。

我为 SL 3 尝试过的一些操作包括:

  • 创建一个“DataTemplatePresenterContentControl”,在加载控件时自动为内容应用 DataTemplate

  • 使用 TypeConverter,在控件加载时动态应用,沿着可视化树查找数据绑定对象

  • < p>使用在控件加载时动态应用的样式,沿着可视化树查找数据绑定对象

但是,没有这些方法确实以可接受的方式解决了我上面提到的情况,这非常关键。

因此,由于这在 Silverlight 4 中仍然不可能开箱即用,我很想知道是否有人已经提出了一些合理的替代方案。

谢谢。

Silverlight 4 is out and it seems we've missed the DataTemplate DataType functionality in this release again, which is pretty pivotal for MVVM support IMHO. For my WPF apps, at this point, I'm pretty used to globally adding DataTemplates for my Views to my Application.Resources with DataTypes for my corresponding ViewModels:

ie.

<DataTemplate DataType="{x:Type viewModels:myViewModel}">
<views:myView/>
</DataTemplate>

I like this approach, since all my bound ViewModels automatically display the correct content...especially useful when I have some ItemSource in my view bound to a collection of ViewModels... This, for example, will automatically make sure each tab in a TabControl bound to a Collection<SomeViewModel> displays the view associated with SomeViewModel.

Some things I tried for SL 3 include:

  • Creating a "DataTemplatePresenterContentControl" which automatically applies a DataTemplate for the Content when the control has loaded

  • Using a TypeConverter, applied dynamically on control load, walking down the visual tree looking for data bound objects

  • Using a style, applied dynamically on control load, walking down the visual tree looking for data bound objects

However, none of these approaches really address the situation I mentioned above in an acceptable way, which is really key.

So, since this still isn't possible out of the box in Silverlight 4, I'd appreciate to know if anyone has yet come up with some reasonable alternatives.

Thanks.

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む无字情书 2024-09-14 23:46:23

我在几个商业项目中的做法如下:

我有一个标准的 IValueConverter

public class ViewTemplateChooser : IValueConverter
{
    /// <summary>
    /// Modifies the source data before passing it to the target for display in the UI.
    /// </summary>
    /// <returns>
    /// The value to be passed to the target dependency property.
    /// </returns>
    /// <param name="value">The source data being passed to the target.</param><param name="targetType">The <see cref="T:System.Type"/> of data expected by the target dependency property.</param><param name="parameter">An optional parameter to be used in the converter logic.</param><param name="culture">The culture of the conversion.</param>
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is MyViewModel)
        {
            return new MyView { DataContext = value };
        }

        return value;
    }

    /// <summary>
    /// Modifies the target data before passing it to the source object.  This method is called only in <see cref="F:System.Windows.Data.BindingMode.TwoWay"/> bindings.
    /// </summary>
    /// <returns>
    /// The value to be passed to the source object.
    /// </returns>
    /// <param name="value">The target data being passed to the source.</param><param name="targetType">The <see cref="T:System.Type"/> of data expected by the source object.</param><param name="parameter">An optional parameter to be used in the converter logic.</param><param name="culture">The culture of the conversion.</param>
    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

该转换器需要命名空间注册

xmlns:Converters="clr-namespace:YourProject.Converters" 

然后您在资源部分中引用该转换器:

<UserControl.Resources>
    <Converters:ViewTemplateChooser x:Key="TemplateChooser" />
</UserControl.Resources>

最后我使用该转换器将 ViewModel 转换为 View将视图的 Datacontext 设置为 ViewModel

<ContentControl Content="{Binding Workspace, Converter={StaticResource TemplateChooser}}" Margin="5,35,5,5" Grid.Column="1" />

转换器可以修改以实现导航策略,我试图使示例尽可能简单。

我希望这会有所帮助,您不必走极端 - 或第三方库 - 来获得您正在寻找的东西。

The way I do it in a couple of commercial projects is as follows:

I have a standard IValueConverter

public class ViewTemplateChooser : IValueConverter
{
    /// <summary>
    /// Modifies the source data before passing it to the target for display in the UI.
    /// </summary>
    /// <returns>
    /// The value to be passed to the target dependency property.
    /// </returns>
    /// <param name="value">The source data being passed to the target.</param><param name="targetType">The <see cref="T:System.Type"/> of data expected by the target dependency property.</param><param name="parameter">An optional parameter to be used in the converter logic.</param><param name="culture">The culture of the conversion.</param>
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is MyViewModel)
        {
            return new MyView { DataContext = value };
        }

        return value;
    }

    /// <summary>
    /// Modifies the target data before passing it to the source object.  This method is called only in <see cref="F:System.Windows.Data.BindingMode.TwoWay"/> bindings.
    /// </summary>
    /// <returns>
    /// The value to be passed to the source object.
    /// </returns>
    /// <param name="value">The target data being passed to the source.</param><param name="targetType">The <see cref="T:System.Type"/> of data expected by the source object.</param><param name="parameter">An optional parameter to be used in the converter logic.</param><param name="culture">The culture of the conversion.</param>
    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

The converter would require a namespace registration

xmlns:Converters="clr-namespace:YourProject.Converters" 

Then you reference the converter in your resources section:

<UserControl.Resources>
    <Converters:ViewTemplateChooser x:Key="TemplateChooser" />
</UserControl.Resources>

and finally I use the converter to convert the ViewModel into a View with the Datacontext of the view set to the ViewModel

<ContentControl Content="{Binding Workspace, Converter={StaticResource TemplateChooser}}" Margin="5,35,5,5" Grid.Column="1" />

The converter can be modified to implement Navigation strategies, I tried to make the example as simple as possible.

I hope this helps, you don't have to go to extremes - or third party libraries - to get what you are looking for.

傲影 2024-09-14 23:46:23

在 WPF 和 Silverlight 中,我使用 Prism 来执行此操作。我发现根据类型切换视图更加通用。需要花费一些时间才能将其绑好,但一旦绑好,就有无限的可能性。

编辑

我通过将 RegionName 绑定到 ViewModel 中的一个属性(如果需要,可以是 GetType().Name)来完成此操作。然后,我注册名称的类型,它就可以工作了。

对于类似 ListBox 的情况,我将数据模板设置为:

<ContentControl Regions:RegionManager.RegionName="{Binding SomeName}" />

如果您不希望 SomeName 位于要绑定到的对象上,请考虑使用返回类型名称的 ValueConverter :

<ContentControl Regions:RegionManager.RegionName="{Binding SomeName, Converter={StaticResource ObjectToTypeConverter}}" />

有帮助吗?

In WPF and Silverlight, I use Prism to do this. I find it to be much more versatile to switch out views based on types. It requires a bit to get it strapped in, but once it is in, the possibilities are endless.

Edit

I do this by binding the RegionName to a property in my ViewModel (Could be GetType().Name if you want). Then, I register the types for the names, and it just works.

In the case of something like a ListBox, I set up the data template to be:

<ContentControl Regions:RegionManager.RegionName="{Binding SomeName}" />

If you don't want SomeName to be on the object you are binding to, consider a ValueConverter that returns the type name:

<ContentControl Regions:RegionManager.RegionName="{Binding SomeName, Converter={StaticResource ObjectToTypeConverter}}" />

Does that help?

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