实例化和重用XAML中的对象实例 [英] Instantiate and reuse instances of objects in XAML

问题描述

我想实例化XAML中的对象，并重用这些实例.我认为这应该很简单，但是我被困住了，我可能缺少明显的东西.

说我想将Cats添加到不同的房间(房间有一个ObservableCollection，其中包含Cat类型的对象).在UserControl.Resources中，我创建ObjectDataProviders:

<ObjectDataProvider x:Key="Cat1" ObjectType="{x:Type local:Cat}">
    <ObjectDataProvider.ConstructorParameters>
        <System:String>Tom</System:String>
    </ObjectDataProvider.ConstructorParameters>
</ObjectDataProvider>
<ObjectDataProvider x:Key="Cat2" ObjectType="{x:Type local:Cat}">
    <ObjectDataProvider.ConstructorParameters>
        <System:String>Garfield</System:String>
    </ObjectDataProvider.ConstructorParameters>
</ObjectDataProvider>
<ObjectDataProvider x:Key="Cat3" ObjectType="{x:Type local:Cat}">
    <ObjectDataProvider.ConstructorParameters>
        <System:String>Furball</System:String>
    </ObjectDataProvider.ConstructorParameters>
</ObjectDataProvider>

在我的UserControl中，我想将猫添加到房间"中:

<local:Room x:Name="Room1">
    <local:Room.Cats>

    </local:Room.Cats>
<local:Room>
<local:Room x:Name="Room2">
    <local:Room.Cats>

    </local:Room.Cats>
<local:Room>

将Cat实例添加到ObservableCollection Room.Cats的语法是什么?例如，我想将Cat1和Cat2添加到Room1，并将Cat2和Cat3添加到Room2.我完全走错了轨道吗?

解决方案

基于海因兹(Heinzi)和罗伯特·罗斯尼(Robert Rossney)的反馈，我提出了以下与ObservableCollection配合使用的解决方案，我可以在XAML中访问它，并在后面进行编码: >

在代码中，我扩展了ObservableCollection，以便可以在XAML中使用它(在XAML 2009中将不再需要):

public class CatObservableCollection : ObservableCollection<Cat> { }

在XAML中的UserControl.Resources中，我实例化了Cats:

<local:Cat x:Key="Tom" Name="Tom"/>
<local:Cat x:Key="Garfield" Name="Garfield"/>
<local:Cat x:Key="Furball" Name="Furball"/>

收藏集:

<local:CatObservableCollection x:Key="Room1Collection">
    <StaticResourceExtension ResourceKey="Tom"/>
    <StaticResourceExtension ResourceKey="Garfield"/>
</local:CatObservableCollection>
<local:CatObservableCollection x:Key="Room2Collection">
    <StaticResourceExtension ResourceKey="Garfield"/>
    <StaticResourceExtension ResourceKey="Furball"/>
</local:CatObservableCollection>

房间的定义如下:

<local:Room x:Name="Room1" Cats="{StaticResource Room1Collection}"/>
<local:Room x:Name="Room2" Cats="{StaticResource Room2Collection}"/>

Room.Cats是一个ObservableCollection< Cat>

I want to instantiate objects in XAML, and reuse these instances. I think it should be simple but I'm stuck, I'm probably missing something obvious.

Say I want to add Cats to different Rooms (Room has an ObservableCollection containing objects of type Cat). In the UserControl.Resources I create ObjectDataProviders:

<ObjectDataProvider x:Key="Cat1" ObjectType="{x:Type local:Cat}">
    <ObjectDataProvider.ConstructorParameters>
        <System:String>Tom</System:String>
    </ObjectDataProvider.ConstructorParameters>
</ObjectDataProvider>
<ObjectDataProvider x:Key="Cat2" ObjectType="{x:Type local:Cat}">
    <ObjectDataProvider.ConstructorParameters>
        <System:String>Garfield</System:String>
    </ObjectDataProvider.ConstructorParameters>
</ObjectDataProvider>
<ObjectDataProvider x:Key="Cat3" ObjectType="{x:Type local:Cat}">
    <ObjectDataProvider.ConstructorParameters>
        <System:String>Furball</System:String>
    </ObjectDataProvider.ConstructorParameters>
</ObjectDataProvider>

In my UserControl I want to add the Cats to the Rooms:

<local:Room x:Name="Room1">
    <local:Room.Cats>

    </local:Room.Cats>
<local:Room>
<local:Room x:Name="Room2">
    <local:Room.Cats>

    </local:Room.Cats>
<local:Room>

What is the syntax for adding the Cat instances to the ObservableCollection Room.Cats? For instance I want to add Cat1 and Cat2 to Room1, and Cat2 and Cat3 to Room2. Am I completely on the wrong track?

解决方案

Based on the feedback from Heinzi and Robert Rossney I came up with the following solution that works with an ObservableCollection that I can access in XAML and code behind:

In code I extended ObservableCollection so I can use it in XAML (this will no longer be necessary in XAML 2009):

public class CatObservableCollection : ObservableCollection<Cat> { }

In XAML in the UserControl.Resources I instantiate the Cats:

<local:Cat x:Key="Tom" Name="Tom"/>
<local:Cat x:Key="Garfield" Name="Garfield"/>
<local:Cat x:Key="Furball" Name="Furball"/>

The collections:

<local:CatObservableCollection x:Key="Room1Collection">
    <StaticResourceExtension ResourceKey="Tom"/>
    <StaticResourceExtension ResourceKey="Garfield"/>
</local:CatObservableCollection>
<local:CatObservableCollection x:Key="Room2Collection">
    <StaticResourceExtension ResourceKey="Garfield"/>
    <StaticResourceExtension ResourceKey="Furball"/>
</local:CatObservableCollection>

The Rooms are now defined as follows:

<local:Room x:Name="Room1" Cats="{StaticResource Room1Collection}"/>
<local:Room x:Name="Room2" Cats="{StaticResource Room2Collection}"/>

Room.Cats is an ObservableCollection<Cat>

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