我如何生成数据库值选择列表？ [英] How do I generate a select list from database values?

问题描述

我想知道什么是具有含有从数据库中值，而不会复制任何code窗体上的选择列表中的最佳方法。

I was wondering what is the best approach to having a select list on a form which contains values from a database without duplicating any code.

我可以用我的想法是有意义的是在控制器中加载这些数据，并把它传递给视图模型，让 SelectListFor＆LT;＆GT; 或任何在为了生成列表。然而，这意味着我必须复制所有的列表装载在GET和POST的两种方法。另一种方法我可以看到会通过数据库上下文到视图模型构造，并加载它的列表中，但是这则presents两个问题：

What I thought would make sense would be to load this data in the controller and pass it to a view model, so I can use SelectListFor<> or whatever in order to generate the list. However this means that I have to duplicate all the list loading in both the GET and the POST methods. The other way I can see would be to pass the database context into the view model constructor and have it load the list , but this then presents two more issues:

1）如果视图模型了解数据库上下文？

1) Should the view model know about the database context?

2）然后我不能用模型通过接受视图模型类型作为方法的参数绑定，因为它没有一个无参数的构造函数（如果我创建一个无参数的构造函数，那么它不会有名单，如果我要重新显示包含表单视图）。

2) I then cannot use model binding by accepting the view model type as a method argument because it does not have a no-argument constructor (if I create a no-argument constructor then it won't have the lists if I want to redisplay the view containing the form).

有没有更好的方法来做到这一点？这似乎是它必须是一个相当常见的场景和任何意见将AP preciated。

Is there a better way to do this? This seems like it must be a fairly common scenario and any advice would be appreciated.

推荐答案

我们通常通过被控制器中使用相同的方式为任何其他存储库交互ReferenceDataRepository实现我们的查找。该库通常使用（会话，AppFabric的等），你选择的缓存方案的抽象收到大量的predominantly静态只读数据呼叫，所以我们可以实现一个派生CachedReferenceDataRepository了这一点。

We typically implement our lookups through a ReferenceDataRepository that gets used within the controllers in the same way as any other repository interaction. This repository will usually recieve a high number of calls for predominantly static readonly data so we may implement a derived CachedReferenceDataRepository over this using an abstraction of your caching scheme of choice (Session, AppFabric etc).

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