问题描述
我将尝试通过想象这个例子来简化我正在处理的任务:
I'll try to simplify the task I'm working on by imagining this example:
假设我们有以下模型类层次结构:
Let's suppose that we have the following hierarchy of model classes:
Animal
Lion
Snake
Bird
...对应的视图模型:
...corresponding ViewModels:
AnimalCollectionViewModel
AnimalViewModel
LionViewModel
SnakeViewModel
BirdViewModel
... 和相应的视图:
... and corresponding views:
AnimalCollectionView
LionView
SnakeView
BirdView
假设 AnimalCollection 包含一个充满不同类型动物对象的列表，在列表下方有一个属性网格，用于设置所选动物的属性.显然，属性网格将具有不同的属性，并且应该在所选项目的类型发生变化时发生变化.
It's supposed that AnimalCollection contains a list filled with objects of different types of animals and below the list it has a property grid for setting the properties of a selected animal. Obviously the property grids will have different properties and should change when the type of a selected item changes.
问题是:如何根据MVVM模式实现WPF中属性网格的切换?使用什么机制?
The question is: How to implement switching of the property grids in WPF according to the MVVM pattern? Using what mechanism?
目前我在基础 ViewModel (AnimalViewModel.PropertyGridType = {Lion, Snake, Bird}) 中有一个抽象枚举属性，派生类通过返回相应的值来实现它.并且 AnimalCollectionView 会根据此属性的值更改属性网格用户控件.像这样:
Currently I have an abstract enum property in the base ViewModel (AnimalViewModel.PropertyGridType = {Lion, Snake, Bird}) which the derived classes implement by returning corresponding values. And the AnimalCollectionView changes the property grid user controls depending on the value of this property. Something like this:
...
<UserControl.Resources>
<Style x:Key="PropertyGridStyle" TargetType="ContentControl">
<Style.Triggers>
<DataTrigger Binding="{Binding PropertyGridType}" Value="Lion">
<Setter Property="Content">
<Setter.Value>
<view:LionPropertyGridView />
</Setter.Value>
</Setter>
</DataTrigger>
<DataTrigger Binding="{Binding PropertyGridType}" Value="Snake">
<Setter Property="Content">
<Setter.Value>
<view:SnakePropertyGridView />
</Setter.Value>
</Setter>
</DataTrigger>
</Style.Triggers>
</Style>
</UserControl.Resources>
<ContentControl Style="{StaticResource PropertyGridStyle}" />
...
但我不确定这是否是正确的方法.(至少我不喜欢引入辅助枚举属性.是否可以根据 ViewModel 类型推导出必要的用户控件?)有人可以建议其他选择吗?提前致谢！
But I'm not sure whether it is the right approach. (At least I don't like introducing the auxiliary enum property. Is it possible to deduce the necessary user control based on a ViewModel type?)Can anybody advise other options?Thanks in advance!
推荐答案
你的意思是，像这样?
<Window.Resources>
<DataTemplate DataType="{x:Type vm:LionViewModel}">
<v:LionView />
</DataTemplate>
<DataTemplate DataType="{x:Type vm:SnakeViewModel}">
<v:SnakeView />
</DataTemplate>
<DataTemplate DataType="{x:Type vm:BirdViewModel}">
<v:BirdView/>
</DataTemplate>
</Window.Resources>
参见将视图应用到视图模型"；在 Josh Smith 关于 MVVM 的文章中.
See "Applying a View to a View Model" in Josh Smith's article on MVVM.
这是一个基于类型的模板选择的简单示例，您可以将其粘贴到 Kaxaml 中以向自己证明它确实有效:
Here's a trivial example of type-based template selection that you can paste into Kaxaml to prove to yourself that it really works:
<Page
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:sys="clr-namespace:System;assembly=mscorlib">
<Page.Resources>
<sys:String x:Key="string">this is a string</sys:String>
<sys:Int32 x:Key="int32">1234</sys:Int32>
<DataTemplate DataType="{x:Type sys:String}">
<TextBlock Foreground="Red" Text="{Binding}"/>
</DataTemplate>
<DataTemplate DataType="{x:Type sys:Int32}">
<TextBlock Foreground="Blue" Text="{Binding}"/>
</DataTemplate>
</Page.Resources>
<StackPanel>
<ContentControl Content="{Binding Source={StaticResource string}}"/>
<ContentControl Content="{Binding Source={StaticResource int32}}"/>
</StackPanel>
</Page>
这篇关于WPF:根据相应的 ViewModels (MVVM) 切换 UserControls的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！