具有不同返回类型的C#通用接口 [英] C# Generic Interface with different return types

问题描述

我有可以以多种格式返回数据的Web服务.例如json和xml.我正在针对此Web服务构建一个简单的C#API，我希望这些方法能够从json，raw json或raw xml返回完全序列化的对象.例如:

I have webservice that can return data in multiple formats. For example json and xml. I'm building a simple C# api against this webservice and I would like the methods to be able to return either fully serialized objects from json, raw json or raw xml. For example:

List<Order> GetOrders(int customerId)
string GetOrders(int customerId)
XMLDocument GetOrders(customerId)

Customer GetCustomer(int customerId)
string GetCustomer(int customerId)
XMLDocument GetCustomer(int customerId)

我有一个关于做一个流畅的api的想法，您可以在其中调用SetFormat()方法，然后该方法将为上述方法返回一个通用接口.但是我一直停留在该接口的外观上，因为返回序列化对象的实现会返回不同类型的对象.

I have an idea about doing a fluent api where you would call a SetFormat() method which would then return a common Interface for the above methods. But I'm stuck on how that interface would look like, since the implementation that returns serialized objects returns objects of different types.

另一个更简单的解决方案是只具有返回序列化对象的方法，然后添加如下这样的out参数:

Another simpler solution would to just have the methods that return serialized objects and then add an out paramater like this:

List<Order> GetOrders(int customerId, out string data)

但是我认为这不是很好的解决方案....

but that's not very nice solution I think....

更新

我更喜欢Sjoerd建议的非通用解决方案，这使我的问题过于复杂.这就是我最终要做的:

I prefered the none-generic solution that Sjoerd suggested, I had over-complicated my problem. This is what I ended up doing:

public class ServiceEntity {
    List<Order> GetOrders(int customerId)....
}    
public class ServiceJson {
    string GetOrders(int customerId)....
}
public class ServiceXml {
    XmlDocument GetOrders(int customerId)....
}

然后像这样的流利的服务课程:

Then a fluent service class like this:

public class Service : IService {
    ....
    public AsJson() { return new ServiceJson(); }
    public AsEntity() { return new ServiceEntity(); }
    public AsXml() { return new ServiceXml(); }
}

像这样使用:

string json = Service.New().AsJson().GetCategories(1);
List<Order> = Service.New().AsEntity().GetCategories(1);

感谢所有回复！

推荐答案

尝试使用泛型很好，但是泛型不是灵丹妙药！

It's nice to try to use generics, but generics are not a silver bullet!

在这种情况下，我想知道与非通用代码相比，您将节省多少代码:

In this case, I wonder how much code would you save compared with the non-generic:

List<Order> GetOrdersAsList(int customerId)
string GetOrdersAsString(int customerId)
XMLDocument GetOrdersAsXml(customerId)

我敢打赌几乎没有！

如果您决定采用非通用方法，则很可能会在内部以以下方式结束:

And in case you decide on the non-generic approach, most likely it would end up internally as:

List<Order> GetOrders(int customerId)
string OrdersToString(List<Order> orders)
XMLDocument OrdersToXml(List<Order> orders)

然后，可以将后两种方法移到单独的类中，从而导致您的 GetOrders()与格式分离.

Then the latter two methods could be moved to separate classes, resulting in the fact that your GetOrders() is uncoupled from the format.

在我看来，这比在这种情况下尝试使用泛型好得多而且更清洁！

That seems to me a much better and cleaner approach than trying to use generics in this case!

更新:别误会，我喜欢泛型，并且在许多情况下，泛型使代码更易读.其他几个答案也很有趣，因为它们显示了达到此目的的技术.因此，我建议对其进行研究:它们在其他情况下可能很有用.但是在这种情况下，到目前为止，每个提出的解决方案都存在实际缺陷.这就是为什么我建议在这种情况下使用非泛型.

UPDATE: Don't get me wrong, I like generics and in many cases they make code more readable. Several other answers are very interesting as they show techniques to achieve that. So I recommend to study them: they might be useful in other cases. But in this case, each proposed solution so far has a practical drawback. That's why I recommend non-generics in this case.

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