在ASP.NET Core API中验证格式无效的值

问题描述

在ASP.NET Core 2.2 API上，我执行以下操作:

On an ASP.NET Core 2.2 API I have the following action:

public async Task<IActionResult> Create([FromBody]Model model) {
}

Model如下:

public class Model {
  public DateTime? PublishedAt { get; set; }
}

属性PublishedAt是必需的，并且必须是过去的.

Property PublishedAt is required and needs to be in the past.

调用该动作时，我可以预测2种不同的情况:

When calling the action I am able to predict 2 different scenarios:

1. 发送到操作的数据不包含PublishedAt或PublishedAt为NULL.

通过使用DateTime?，我可以检查它是否为NULL或在过去的情况下(如果已定义).

By using DateTime? I am able to check if it is NULL or in the past in case it is defined.

这有意义吗?

发送到操作的数据包含无效的PublishedAt日期(2019-20-40).

Data sent to action includes an invalid PublishedAt date (2019-20-40).

在这种情况下，我意识到Model为空，所以我无法对其进行验证.

In this case I realised that Model becomes null so I cannot validate it.

我也无法发送回友好消息，例如:

I also cannot send back a friendly message such as:

发布日期格式无效"

当DateTime格式错误时，如何返回友好消息?

我想避免将String用作PublishedAt的数据类型.

I would like to avoid using String as data type for PublishedAt.

也许正在使用自定义的Model Binder?

Maybe using a custom Model Binder?

推荐答案

尝试使用FluentValidation.您可以在此处详细了解.这是一个NuGet程序包，您可以通过NuGet.org 下载.安装后，您可以在ConfigureServices中进行注册，如下所示:

Try using FluentValidation. You can read about it here in detail. It's a NuGet package that you can download via NuGet.org. Once installed you can register it in ConfigureServices like below:

1 public void ConfigureServices(IServiceCollection services)
2 {
3    services.AddMvc(setup => {
4      //...mvc setup...
5    }).AddFluentValidation(configuration => configuration
6      .RegisterValidatorsFromAssemblyContaining<Startup>());
7 }

第5行和第6行将自动查找从AbstractValidator继承的任何公共的非抽象类型，并将它们注册到容器中.然后，按如下所示为Model定义AbstractValidator

Line number 5 and 6 will automatically find any public, non-abstract types that inherit from AbstractValidator and register them with the container. You then define your AbstractValidator for Model as below

在创建AbstractValidator

如果您确实要避免将PublishedAt更改为string， 您可以通过稍微更改规则来尝试相同的方法，然后查看 如果适合您

If you really want to avoid changing the PublishedAt to string, you can try the same approach by changing the rules slightly and see if that works for you

public class ModelValidator : AbstractValidator<Model>
{
    public ModelValidator()
    {
        // add a rule that Date must be in the past, shouldn't be empty
        // and in the correct format
        RuleFor(model => model.PublishedAt)
           .Cascade(CascadeMode.StopOnFirstFailure)
           .Must(date => !string.IsNullOrWhiteSpace(date))
               .WithMessage("PublishAt is a required parameter")
           .Must(arg =>
           {
               if (DateTime.TryParseExact(arg.ToString(), new[] { "dd-MMM-yyyy" }, CultureInfo.InvariantCulture, DateTimeStyles.None, out DateTime date))
               {
                   return date < DateTime.Now;
               }

               return false;
            })
            .When(model => !string.IsNullOrWhiteSpace(model.PublishedAt))
            .WithMessage("Argument PublishAt is invalid. Please specify the date in dd-MMM-yyy and should be in the past");
    }
}

上面的验证器将在模型绑定过程之后执行，如果验证失败，则WithMessage语句会将错误添加到ModelState.由于您具有[ApiController]属性.您的模型将通过验证，并将返回您在WithMessage语句中指定的消息.

The above validator will be executed after the model binding process and if the validation fails, WithMessage statements will add the error to the ModelState. As you have [ApiController] attribute. Your model will be validated and it will return the messages you specified in the WithMessage statements.

或者您可以手动检查action方法内的ModelState.IsValid并返回带有ModelState的ObjectResult.

Or you can manually check if the ModelState.IsValid inside the action method and return the ObjectResult with the ModelState.

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