WPF 动态向类添加属性并稍后通过 BindingExtension 检索它们

Question

我希望能够在运行时向类添加属性，并稍后通过 BindingExtension 访问这些属性，例如：

class PropertiesHolder {
    properties = [];
}


class PropertiesAdder {
    propertiesHolder.properties.add(PropertyA);
    propertiesHolder.properties.add(PropertyB);
}

Content="{Binding PropertyB}"

然后 XAML 将检索存储在对象“PropertyB”中的值

我面临的问题是没有办法区分这些不同的属性。我可以动态地将一堆数据放入 ObservableCollection 或其他东西中，但如果我创建两个或多个，我不知道如何通过数据绑定区分它们，因为 Binding 采用指向属性的路径。我不能说，在属性中存储 UID，因为显然，Binding 在第一次获取对象之前不会关心对象内部的信息。

Answer 1

看这个例子：

// This is the namespace for my implementation of the ViewModelBase class.
// Since you will have your own implementation or use some kind of package,
// you need to change this `using` to the one that is relevant for you.
using Simplified;

using System.Dynamic;

namespace Core2024.SO.ExpandoObjectTest
{
    public class EOtestVM : ViewModelBase
    {
        public dynamic EO { get; }
        private readonly IDictionary<string, object?> properties;

        public EOtestVM()
        {
            properties = EO = new ExpandoObject();
        }

        public RelayCommand AddPropertyA => GetCommand(() => EO.PropertyA = 1, () => !properties.ContainsKey("PropertyA"));

        public RelayCommand IncrementPropertyA => GetCommand(() => EO.PropertyA++, () => properties.ContainsKey("PropertyA"));

        public RelayCommand AddPropertyB => GetCommand(() => properties.Add("PropertyB", 1), () => !properties.ContainsKey("PropertyB"));

        public RelayCommand IncrementPropertyB => GetCommand(() => properties["PropertyB"] = ((int)properties["PropertyB"]) + 1, () => properties.ContainsKey("PropertyB"));
    }

}

<Window x:Class="Core2024.SO.ExpandoObjectTest.EOtestWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:Core2024.SO.ExpandoObjectTest"
        mc:Ignorable="d"
        Title="EOtestWindow" Height="450" Width="800">
    <Window.DataContext>
        <local:EOtestVM/>
    </Window.DataContext>
    <UniformGrid Columns="2">
        <Viewbox>
            <TextBlock Text="{Binding EO.PropertyA}"/>
        </Viewbox>
        <Viewbox>
            <TextBlock Text="{Binding EO.PropertyB}"/>
        </Viewbox>
        <Button Content="Add PropertyA" Command="{Binding AddPropertyA, Mode=OneWay}"/>
        <Button Content="Add PropertyB" Command="{Binding AddPropertyB, Mode=OneWay}"/>
        <Button Content="Increment PropertyA" Command="{Binding IncrementPropertyA, Mode=OneWay}"/>
        <Button Content="Increment PropertyB" Command="{Binding IncrementPropertyB, Mode=OneWay}"/>
    </UniformGrid>
</Window>