一般返回来自实体框架项目 [英] Generically return an item from Entity Framework

问题描述

我有一种情况，网站可以从数据库中请求数据基于字符串（不要担心 - 我防范SQL注入）。由于各种原因，我想有一个方法返回用户期望的对象（从EF返回）（它最终通过部分页面返回）。

I have a situation where a website can ask for data from my database based on a string (don't worry - I'm protecting against SQL injections). For various reasons, I would like to have a single method which returns back the object (from EF) that the user expects (which, ultimately, comes back through a partial page).

我在这样想：

public <GenericType?> GetObject(int id, string typeName) {
  switch(typeName) {
    case "Type1":
      return db.Type1s.SingleOrDefault(t => t.TypeID == id);
    case "Type2":
      return db.Type2.SingleOrDefault(t => t.TypeID == id);
    default:
      return null;
  }
}

可以这样做吗？ （我想避免的是先做switch语句，然后调用特定的Repository方法，因为我将不得不重复代码，这样做了很多次。）

Is it possible to do something like this? (What I am trying to avoid is having to do the switch statement earlier and then call the specific Repository method because I would then have to repeat code and do this a number of times.)

推荐答案

CreateQuery< T> 可能是您需要的。

实体框架是否具有相当于DataContext.GetTable从Linq2Sql（ObjectContext.CreateQuery？）

有什么办法你可以得到所有可能的类型，你会传递来comport一个具有此TypeID属性的特定接口？如果是，如何：

Is there any way you can get all the possible types you'd be passing in to comport with a particular interface that has this TypeID property on it? If so, how about:

    public T GetResult<T>(int id, string typeName) where T : IClassWithTypeID {
        YourEntities db = new YourEntities();
        var result = db.CreateQuery<T>(String.Format("[{0}]", typeName));

        return result.Single(t => t.TypeID == id);
    }

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