如何使用时，获得的数据将DropDownList到视图模型AutoMapper / AutoMapViewResult [英] How to get data for a dropdownlist into viewmodel when using AutoMapper/AutoMapViewResult

问题描述

在行动阅读 ASP.NET MVC 2和看的从mvcConf （均强烈推荐！），我开始实施他们的一些想法。吉米·博加德的presentation

After reading ASP.NET MVC 2 in Action and watching Jimmy Bogard's presentation from MvcConf (both highly recommended!), I began to implement some of their ideas.

一个他们做的很酷的事情，不仅要使用AutoMapper你的实体映射到某个视图模型，但有一个AutoMapViewResult自动完成：

One of the cool things they do, is not only to use AutoMapper to map your entities to some viewmodel, but automate this with an AutoMapViewResult:

public class EventsController : BaseController
{
    public ActionResult Show(Event id) // EntityModelBinder gets Event from repository
    {
        return AutoMapView<EventsShowModel>(id); // AutoMapView<T>(model) is a helper method on the BaseController, that calls AutoMapViewResult<T>(...)
    }
}

// not exactly what you'll find in the book, but it also works :-)
public class AutoMapViewResult<TDestination> : ViewResult
{
    public AutoMapViewResult(string viewName, string masterName, object model)
    {
        ViewName = viewName;
        MasterName = masterName;

        ViewData.Model = Mapper.Map(model, model.GetType(), typeof(TDestination));
    }
}

这一切的伟大工程，但现在有一个修改操作的 EventsEditModel ：

This all works great, but now there's a Edit action with its EventsEditModel:

public class EventsEditModel
{
    // ... some properties ...
    public int LocationId { get; set; }
    public IList<SelectListItem> Locations { get; set; }
}

public class EventsController : BaseController
{
    public ActionResult Edit(Event id)
    {
        return AutoMapView<EventsEditModel>(id); 
    }
}

现在（终于）问题：

你觉得什么，是让某些类型的数据源，如存储库的位置的最佳途径的 EventsEditModel 位置属性？

What do you think, is the best way to get the locations from some sort of data source such as a repository to the EventsEditModel's Locations property?

请记住，我想使用 AutoMapViewResult 和很多不同的实体视图模型组合。

Keep in mind, that I want to use the AutoMapViewResult and a lot of different entity-viewmodel combinations.

更新：

我去丧尸的想法，并创建了一个自定义属性。你可以看一下在code和下载它在我的博客<一href=\"http://blog.opo.li/post/ASPNET-MVC-Loading-data-for-select-lists-into-edit-model-using-attributes.aspx\">ASP.NET MVC：加载数据选择列表进入编辑模式使用属性

I went with Necros' idea and created a custom attribute. You can look at the code and download it on my blog ASP.NET MVC: Loading data for select lists into edit model using attributes.

推荐答案

我没有得到的点（因为我看到了谈话），当我需要这一点，但我心里有这个可能的解决方案。我认为这将努力创造一个属性，指定这个属性需要加载。我会先从一个抽象类：

I haven't gotten to the point (since I saw the talk) when I needed this, but I have a possible solution for this in mind. I think it would work to create an attribute, specifying that this property needs to be loaded. I would start with an abstract class:

public abstract class LoadDataAttribute : Attribute
{
    public Type Type { get; set; }

    protected LoadDataAttribute(Type type)
    {
        Type = type;
    }

    public abstract object LoadData();
}

那么对于要加载每个类型创建特定的版本（在你的案件位置）

Then create specific version for each type you want to load (Locations in your case)

public class LoadLocationsAttribute : LoadDataAttribute
{
    public LoadLocationsAttribute() : base(typeof(IList<SelectListItem>))

    public override object LoadData()
    {
        // get locations and return IList<SelectListItem>
    }
}

在你的的ExecuteReuslt AutoMappViewResult 你会找到 LoadDataAttribute ，电话 LoadData（），将它转换为类型属性中指定，并将其分配给属性。

In your ExecuteResult of AutoMappViewResult you would find all properties with LoadDataAttribute, call LoadData(), cast it to type specified in the attribute and assign it to the property.

我如果你只是要加载选择列表这种方式，你可以只返回的IList＆LT; SelectListItem＆GT; 而不是对象，并保存自己一些麻烦铸造。

I case you just want to load select lists this way, you can just return IList<SelectListItem> instead of object, and save yourself some trouble with casting.

您的视图模型将在明显的使用属性。

Your view model would the obviously use the attribute.

public class EventsEditModel
{
    // ... some properties ...
    public int LocationId { get; set; }

    [LoadLocations]
    public IList<SelectListItem> Locations { get; set; }
}

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