c# - 具有枚举输入参数的 Webapi post 方法

Question

为什么在尝试调用采用枚举作为输入参数的 Web API 方法时会出现以下屏幕截图中的错误？我该如何解决这个问题？

无论我做什么，messageDestinationType 似乎始终为 null...

我更愿意将输入类型保留为枚举。我对使用 web api 很陌生，无法理解当 WCF 完美处理这种情况时这有多么困难

[JsonConverter(typeof(StringEnumConverter))]    
public enum MessageDestinationType
{
    None = 0,
    [EnumMember(Value = "SMS")]
    SMS = 1,
    [EnumMember(Value = "Email")]
    Email = 2,
    PushNotification = 3,
    UXP = 4,
    IntermediaryApp = 5,
    YouthApp = 6
}



    [HttpPost, Route("ReadClientMessagesC")]
    public IHttpActionResult ReadClientMessagesC([FromBody]MessageDestinationType messageDestinationType)
    {
        var request = new ClientInboxRequest
        {
            Gcn = Gcn,
            ClientIpAddress = ClientIpAddress,
            CallingApplication = CallingApplication.Name,
            CallingApplicationVersion = CallingApplication.Version,
            CookieString = CookieString,
            HasPbUk = HasPbUk,
            HasIamIms = HasIamIms,
            HasPbZa = HasPbZa,
            HasSps = HasSps,
            HasWiUk = HasWiUk,
            HasWiZa = HasWiZa,
            LinkedGcns = LinkedGcns,
            RequestId = RequestId.ToString(),
            SsoProfiles = SsoProfiles.Select(x => x.Name).ToList()
        };

        MessageDestinationType messageDestination = (MessageDestinationType)messageDestinationType;

        return Ok(ClientMessageCenterHelper.ReadClientMessagesA(Gcn, messageDestination, request));
    }

Error message: { "Message": "The request is invalid.", "MessageDetail": "The parameters dictionary contains a null entry for parameter 'messageDestinationType' of non-nullable type 'API.Domain.ClientMessageCenter.MessageDestinationType' for method 'System.Web.Http.IHttpActionResult ReadClientMessagesC(API.Domain.ClientMessageCenter.MessageDestinationType)' in 'ID.ClientMessageCenter.Controllers.ClientMessageCenterController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter." }

Answer 1

您可以将字符串(enum 的字符串名称)发送到 Web API Controller (即使它具有类似于 OP 示例中的数值)。 ASP.NET 框架已经规定了自动进行这种转换 - 您只需启用它即可。

在您的 Startup.cs ConfigureServices 方法中，将您的转换器添加到 JsonSerializerOptions.Converters 属性。

services.AddControllers()
    .AddJsonOptions(opts =>
    {
        opts.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter());
        opts.JsonSerializerOptions.IgnoreNullValues = true;
    });

我还建议将 IgnoreNullValues 设置为您喜欢的设置，以使其非常明确。

信用:我从 this post 解决了我的问题(by regisdiogo)并无耻地复制到这里:-)