正在解析通过Simple Injector注册的ASP.NET Web窗体图像控件派生类

Question

我要将一个存储库实例注入一些Web.UI.WebControls.Image派生类型：

public class CustomImageControl : Image
{
    [Import]
    public ICachedNameRepository Repo { get; set; } // Null reference here
    private void DynamicImage_PreRender(object sender, EventArgs e)
    {
        ImageUrl = {some ICachedNameRepository usage}
    }
}

这里还有我为测试目的实现的默认页面：

public partial class _Default : Page
{
    [Import]
    public ICachedNameRepository Repo { get; set; } // Totally ok here
    protected void Page_Load(object sender, EventArgs e)
    {
        {some ICachedNameRepository usage}
    }
}

我已经根据官方指南实现了容器引导，使用控制注册而不是页面：

    private void BootStrapContainer()
    {
        var container = new Container();
        container.Options.PropertySelectionBehavior = new ImportAttributePropertySelectionBehavior();            
        container.Register<ICachedNameRepository, CachedNameRepository>();
        container.Register<CustomImageControl>(); // Also I have tried Control and Image types
        container.Register<Page>();
        var cc = container.GetInstance<CustomImageControl>(); // Correctly instantiated CachedNameRepository instance in Repo field in cc object
        container.Verify(); // OK here
        Global.Container = container;
    }

我让ControlInitializerModule、ImportAttributePropertySelectionBehavior和InitializeHandler例程完全从前面提到的指南中复制粘贴

在页面加载时，我最终得到了正确解析的默认页面实例，CachedNameRepository被注入到了正确的位置，但我的CustomImageControl受到了null引用的影响。

Answer 1

这可以通过挂接到Page的InitComplete事件来完成。这是我用来证明这一点的代码。

我将CustomImageControl更改为从UserControl:继承

public partial class CustomImageControl : UserControl
{
    [Import]
    public ICachedNameRepository Repo { get; set; }
    private void DynamicImage_PreRender(object sender, EventArgs e)
    {
    }
}

这是更新的InitializeHandler

public class Global : HttpApplication
{
    private static Container container;
    public static void InitializeHandler(IHttpHandler handler)
    {
        if (handler is Page)
        {
            Global.InitializePage((Page)handler);
        }
    }
    private static void InitializePage(Page page)
    {
        container.GetRegistration(page.GetType(), true).Registration
            .InitializeInstance(page);
        page.InitComplete += delegate { Global.InitializeControl(page); };
    }
    private static void InitializeControl(Control control)
    {
        if (control is UserControl)
        {
            container.GetRegistration(control.GetType(), true).Registration
                .InitializeInstance(control);
        }
        foreach (Control child in control.Controls)
        {
            Global.InitializeControl(child);
        }
    }

以及文档中的其他2项更改。请务必在引导程序中调用RegisterWebPagesAndControls

private static void RegisterWebPagesAndControls(Container container)
{
    var pageTypes =
        from assembly in BuildManager.GetReferencedAssemblies().Cast<Assembly>()
        where !assembly.IsDynamic
        where !assembly.GlobalAssemblyCache
        from type in assembly.GetExportedTypes()
        where type.IsSubclassOf(typeof(Page)) || type.IsSubclassOf(typeof(UserControl))
        where !type.IsAbstract && !type.IsGenericType
        select type;
    pageTypes.ToList().ForEach(container.Register);
}
class ImportAttributePropertySelectionBehavior : IPropertySelectionBehavior
{
    public bool SelectProperty(Type serviceType, PropertyInfo propertyInfo)
    {
        // Makes use of the System.ComponentModel.Composition assembly
        return (typeof(Page).IsAssignableFrom(serviceType) ||
            typeof(UserControl).IsAssignableFrom(serviceType)) &&
            propertyInfo.GetCustomAttributes<ImportAttribute>().Any();
    }
}