c# - .net从抽象类创建对象实例

Question

我有以下抽象类:

public abstract class TemplateBase
{
    public abstract string TemplateName { get; }
    public string RuntimeTypeName { get { return GetType().FullName; } }
    public abstract List<AreaContainer> TemplateAreas { get; }
}

然后这2个继承类:

public class SingleColumnTemplate : TemplateBase
{
    public override string TemplateName { get { return "Single column"; } }

    public AreaContainer CenterColumn { get; private set; }

    public SingleColumnTemplate()
    {
        this.CenterColumn = new AreaContainer("Middle");
    }

    private List<AreaContainer> templateAreas;

    public override List<AreaContainer> TemplateAreas
    {
        get
        {
            if (this.templateAreas == null)
            {
                this.templateAreas = new List<AreaContainer>() { this.CenterColumn };
            }

            return this.templateAreas;
        }
    }
}

和

public class TwoColumnTemplate : TemplateBase
{
    public override string TemplateName { get { return "Two column"; } }
    public AreaContainer LeftColumn { get; private set; }
    public AreaContainer RightColumn { get; private set; }

    public TwoColumnTemplate()
    {
        LeftColumn = new AreaContainer("Left");
        RightColumn = new AreaContainer("Right");
    }

    private List<AreaContainer> templateAreas;

    public override List<AreaContainer> TemplateAreas
    {
        get
        {
            if (this.templateAreas == null)
            {
                this.templateAreas = new List<AreaContainer>() { this.LeftColumn, this.RightColumn };
            }
            return this.templateAreas;
        }
    }
}

我还有这个类，它是我的编辑模型:

public class ContentPage
{
    public virtual int ContentPageId { get; set; }

    public virtual string Title { get; set; }

    public TemplateBase Template { get; set; }
}

问题:

对于我的 ActionResults，我有以下内容:

[HttpGet]
public ActionResult Edit()
{
    var row = new ContentPage();
    var template = new TwoColumnTemplate();        

    // Areas
    HtmlArea html_left = new HtmlArea();
    html_left.HtmlContent = "left area html content";

    HtmlArea html_right = new HtmlArea();
    html_right.HtmlContent = "right area html content";

    template.LeftColumn.Areas.Add(html_left);
    template.RightColumn.Areas.Add(html_right);

    row.Template = template;
    return View(row);
}

[HttpPost]
[ValidateInput(false)]
public ActionResult Edit(ContentPage row)
{
    // Here i could loop through List -TemplateAreas and save each template Area to Db. I guess that would work

    return this.View(row);
}

问题:

对于 HttpGet - 我将如何从数据库加载行模板？因为它可以是 SingleColumnClass 或 TwoColumnClass。

我的 ViewModel 会如何解决这个问题？

谢谢

Answer 1

您可以编写自己的模型绑定(bind)器来负责绑定(bind)TemplateBase。您仍然需要有一种方法(在模型绑定(bind)器中)知道您将使用运行时的类型，但您始终可以将其委托(delegate)给某种工厂或服务定位器。我进行了快速的谷歌搜索，这是我发现的一篇博客文章，它为您提供了一些为类似场景制作模型绑定(bind)程序的信息:

http://weblogs.asp.net/bhaskarghosh/archive/2009/07/08/7143564.aspx

编辑:该博客遗漏了如何向 MVC 告知模型绑定(bind)程序。当应用程序启动时，您可以将模型绑定(bind)器添加到 System.Web.Mvc.ModelBinders.Binders

HTH