C# 验证Web api 2对象参数中的枚举

假设您向控制器发送一个类实例，并且该类具有枚举类型的属性

public class CoffeeController : ApiController
{
    [HttpPost]
    public async Task<IHttpActionResult> OrderAsync(Order request)
    {
        return Ok();
    }
}

public enum CoffeeType
{
    Latte,
    Mocha,
    Espresso
}

public class Order
{
    public CoffeeType Type { get; set; }
    public string Name { get; set; }
}

我觉得这很奇怪。 为什么使用这种行为

---

是否有一种优雅的方法抛出错误？

之所以这样做，是因为枚举基于整数类型，因此它们总是有一个值（值类型不能为null），并且默认为0。使用以下解决方法

public enum CoffeeType
{
    Invalid = 0
    Latte = 1,
    Mocha = 2,
    Espresso = 3
}

---

对模型应用验证。创建一个

ActionFilterAttribute

，并将其连接到管道中或用它装饰端点。建议您也考虑作为一个伟大的图书馆来执行验证。

---

请参阅中的示例以了解一个很好的示例。

正如Brett所写，您可以使用ModelState.IsValid，ModelState将出现错误。 如果需要抛出错误，您可以为您的类型使用自定义媒体格式化程序，如：

public class OrderJsonFormatter : BufferedMediaTypeFormatter
    {
        public OrderJsonFormatter()
        {
            SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/json"));
        }

        public override bool CanReadType(Type type)
        {
            var canRead = type == typeof(Order);
            return canRead;
        }

        public override bool CanWriteType(Type type)
        {
            return false;
        }

        public override object ReadFromStream(Type type, Stream readStream, HttpContent content, IFormatterLogger formatterLogger)
        {
            return this.ReadFromStream(type, readStream, content, formatterLogger, CancellationToken.None);
        }

        public override object ReadFromStream(Type type, Stream readStream, HttpContent content, IFormatterLogger formatterLogger, CancellationToken cancellationToken)
        {
            using (var reader = new StreamReader(readStream))
            {
                using (var jsonReader = new JsonTextReader(reader))
                {
                    var jsonSerializer = new JsonSerializer();

                    if (type == typeof(Order))
                    {


                        try
                        {
                            var entity = jsonSerializer.Deserialize<Order>(jsonReader);
                            return entity;
                        }
                        catch (Exception ex)
                        {
                         //log error here
                            throw;
                        }
                    }

                    return null;
                }
            }
        }


    }

public class OrderJsonFormatter : BufferedMediaTypeFormatter
    {
        public OrderJsonFormatter()
        {
            SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/json"));
        }

        public override bool CanReadType(Type type)
        {
            var canRead = type == typeof(Order);
            return canRead;
        }

        public override bool CanWriteType(Type type)
        {
            return false;
        }

        public override object ReadFromStream(Type type, Stream readStream, HttpContent content, IFormatterLogger formatterLogger)
        {
            return this.ReadFromStream(type, readStream, content, formatterLogger, CancellationToken.None);
        }

        public override object ReadFromStream(Type type, Stream readStream, HttpContent content, IFormatterLogger formatterLogger, CancellationToken cancellationToken)
        {
            using (var reader = new StreamReader(readStream))
            {
                using (var jsonReader = new JsonTextReader(reader))
                {
                    var jsonSerializer = new JsonSerializer();

                    if (type == typeof(Order))
                    {


                        try
                        {
                            var entity = jsonSerializer.Deserialize<Order>(jsonReader);
                            return entity;
                        }
                        catch (Exception ex)
                        {
                         //log error here
                            throw;
                        }
                    }

                    return null;
                }
            }
        }


    }

 GlobalConfiguration.Configuration.Formatters.Insert(0, new OrderJsonFormatter());