为创建一个模型通用save（）方法 [英] Creating a Generic Save() Method for Models

问题描述

我有一个相当简单的系统，并为这一问题的目的，基本上有三个部分：模型，库，应用程序代码

I have a fairly simple system, and for the purposes of this question there are essentially three parts: Models, Repositories, Application Code.

目前的核心是楷模。让我们用一个简单的人为的例子：

At the core are the models. Let's use a simple contrived example:

public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

在这同一个项目是一个通用库接口。在最简单的：

In that same project is a generic repository interface. At its simplest:

public interface IRepository<T>
{
    T Save(T model);
}

实现，在一个单独的项目，并与StructureMap注入。为简单起见：

Implementations of that interface are in a separate project and injected with StructureMap. For simplicity:

public class PersonRepository : IRepository<Person>
{
    public Person Save(Person model)
    {
        throw new NotImplementedException("I got to the save method!");
        // In the repository methods I would interact with the database, or
        // potentially with some other service for data persistence.  For
        // now I'm just using LINQ to SQL to a single database, but in the
        // future there will be more databases, external services, etc. all
        // abstracted behind here.
    }
}

所以，在应用程序代码，如果我想保存一个模式，我会做这样的：

So, in application code, if I wanted to save a model I would do this:

var rep = IoCFactory.Current.Container.GetInstance<IRepository<Person>>();
myPerson = rep.Save(myPerson);

简单，但感觉就像它可以自动不少。这种模式拥有整个应用程序的代码，所以我在寻找什么做的就是创建一个通用的保存（）在所有型号上这也只是上面的简写电话应用程序代码。这样，一会只需要调用：

Simple enough, but it feels like it could be automated a lot. That pattern holds throughout the application code, so what I'm looking to do is create a single generic Save() on all models which would just be a shorthand call to the above application code. That way one would need only call:

myPerson.Save();

但我似乎无法想出一个办法做到这一点。也许这看似简单，我只是没有从正确的角度看它。起初，我试图创建一个空的 ISaveableModel< T> 接口，并打算让每一个拯救-能的模式实现它，那么对于单个通用保存（）方法，我会在界面上的扩展：

But I can't seem to figure out a way to do it. Maybe it's deceptively simple and I'm just not looking at it from the correct angle. At first I tried creating an empty ISaveableModel<T> interface and intended to have each "save-able" model implement it, then for the single generic Save() method I would have an extension on the interface:

public static void Save<T>(this ISaveableModel<T> model)
{
    var rep = IoCFactory.Current.Container.GetInstance<IRepository<T>>();
    model = rep.Save(model);
}

但它告诉我， rep.Save（模型）具有无效的参数。看来，它不是布线了类型推断为我所希望的那样。我试着用 BaseModel℃的类似的方法; T> 类从该款车型将继承：

But it tells me that rep.Save(model) has invalid arguments. It seems that it's not wiring up the type inference as I'd hoped it would. I tried a similar approach with a BaseModel<T> class from which models would inherit:

public class BaseModel<T>
{
    public void Save()
    {
        this = IoCFactory.Current.Container.GetInstance<IRepository<T>>().Save(this);
    }
}

但是，编译器误差是相同的。有没有办法达到我想要达到什么目的？我在设计上非常灵活，所以如果我要的东西都错了一个建筑的水平，那么我有房退后一步，改变大局。

But the compiler error is the same. Is there a way to achieve what I'm trying to achieve? I'm very flexible on the design, so if I'm going about something all wrong on an architectural level then I have room to step back and change the big picture.

推荐答案

一下通用的扩展方法解决这个问题。

Would a generic extension method solve it?

public static T Save<T>(this T current)
{
    var rep = IoCFactory.Current.Container.GetInstance<IRepository<T>>();
    rep.Save(current);
}

您可以将其约束到你的 ISaveableModel< T> ; 接口。返回类型上面没有实现，但你可以把它放到一个布尔值或状态标志，等等。

You can then constrain it to your ISaveableModel<T> interface. Return type above not implemented, but you can put it to a boolean or status flag, whatever.

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