依赖注入在网页API验证 [英] Dependency-Injected Validation in Web API

问题描述

在MVC中，我可以创建一个模型验证可以采取的依赖关系。我通常使用FluentValidation这一点。这让我，比如，检查，一个电子邮件地址尚未使用的帐号注册（注：这是一个简单的例子！）：

In MVC, I can create a Model Validator which can take Dependencies. I normally use FluentValidation for this. This allows me to, for example, check on account registration that an e-mail address hasn't been used (NB: This is a simplified example!):

public class RegisterModelValidator : AbstractValidator<RegisterModel> {
    private readonly MyContext _context;
    public RegisterModelValidator(MyContext context) {
        _context = context;
    }
    public override ValidationResult Validate(ValidationContext<RegisterModel> context) {
        var result = base.Validate(context);
        if (context.Accounts.Any(acc => acc.Email == context.InstanceToValidate.Email)){
            result.Errors.Add(new ValidationFailure("Email", "Email has been used"));
        }
        return result;
    }
}

没有这种整合存在是为了与FluentValidation的Web API。曾有的<一个一个夫妇 href=\"https://fluentvalidation.$c$cplex.com/SourceControl/network/forks/paulduran/webapisupportv2/contribution/3940\">attempts这个，但也已经攻克了依赖注入方面，只有静态验证工作。

No such integration exists for Web API with FluentValidation. There have been a couple of attempts at this, but neither have tackled the Dependency Injection aspect and only work with static validators.

究其原因，这是困难的是由于MVC和Web API之间实现ModelValidatorProvider和ModelValidator的不同。在MVC中，这些都是每个请求实例化（因此注入上下文很简单）。在网页API，它们是静态的，而ModelValidatorProvider保持每个类型ModelValidators的高速缓存，以避免在每次请求不必要的反射查找。

The reason this is difficult is due to the different in implementation of ModelValidatorProvider and ModelValidator between MVC and Web API. In MVC, these are instantiated per-request (hence injecting a context is easy). In Web API, they are static, and the ModelValidatorProvider maintains a cache of ModelValidators per type, to avoid unnecessary reflection lookups on every request.

我一直在尝试添加必要的整合自己，但一直卡住试图获得依赖范围。相反，我以为我会退后一步，询问是否有任何其他解决问题的办法 - 如果有人想出了一个解决方案来进行模型验证依赖哪里可以注射

I've been trying to add the necessary integration myself, but have been stuck trying to obtain the Dependency Scope. Instead, I thought I'd step back and ask if there any other solutions to the problem - if anyone has come up with a solution to performing Model Validation where dependencies can be injected.

我不希望到控制器内执行验证（我使用的是 ValidationActionFilter 保持这种独立的），这意味着我无法从控制器的构造器注入任何帮助。

I do NOT want to perform the validation within the Controller (I am using a ValidationActionFilter to keep this separate), which means I can't get any help from the constructor injection of the controller.

推荐答案

我终于得到这个工作，但它是一个有点bodge的。正如前面提到的，ModelValidatorProvider将保持周围所有验证的辛格尔顿实例，所以这是完全不适合。相反，我使用的过滤器来运行我自己的验证，通过对立的建议。该过滤器可以访问 IDependencyScope ，可以整齐实例验证。

I've finally got this to work, but it's a bit of a bodge. As mentioned earlier, the ModelValidatorProvider will keep Singleton instances of all Validators around, so this was completely unsuitable. Instead, I'm using a Filter to run my own validation, as suggested by Oppositional. This filter has access to the IDependencyScope and can instantiate validators neatly.

中的过滤器，我经过 ActionArguments ，并通过审定通过他们。验证code被复制出来的网页API运行源为 DefaultBodyModelValidator ，修改，查找在 DependencyScope 。

Within the Filter, I go through the ActionArguments, and pass them through validation. The validation code was copied out of the Web API runtime source for DefaultBodyModelValidator, modified to look for the Validator within the DependencyScope.

最后，为了与 ValidationActionFilter ，你需要的确保您的过滤器在一个特定的顺序执行。

Finally, to make this work with the ValidationActionFilter, you need to ensure that your filters are executed in a specific order.

我打包我的解决方案了在 github上，用版本上的NuGet。

I've packaged my solution up on github, with a version available on nuget.

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