c# - 验证 GUID 作为参数

Question

我的路线是:

public void RegisterRoute(HttpRouteCollection routes) {
    routes.MapHttpRoute(
        name: "DefaultApi",
        routeTemplate: "api/{controller}/{guid}",
        defaults: new { guid = RouteParameter.Optional }
    );
}

Controller Action 就像

public IHttpActionResult Get(Guid guid) {

当我传递api/{controller}/2ADEA345-7F7A-4313-87AE-F05E8B2DE678时，一切正常，但是当我传递无效的guid值时，例如

api/{controller}/xxxxxx 然后我收到错误:

{
  "message": "The request is invalid.",
  "messageDetail": "The parameters dictionary contains a null entry for parameter 'guid' of non-nullable type 'System.Guid' for method 'System.Web.Http.IHttpActionResult Get(System.Guid)' in 'Web.API.Controller.UserController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter."
}

如何显示我自己的消息，例如:

{
  "guid": "The value is invalid.",
}

我正在尝试创建自定义模型绑定(bind)程序，但它不起作用

public class GuidModelBinder : IModelBinder {

        public bool BindModel(HttpActionContext actionContext, ModelBindingContext bindingContext) {
            var value = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
            if (value == null) {
                bindingContext.ModelState.AddModelError("guid", "The value is invalid");
                return false;
            }


            var result = Guid.TryParse(value.ToString(), out _);
            if (!result) {
                bindingContext.ModelState.AddModelError("guid", "The value is invalid");
            }
            return result;
        }
    }

请帮忙。如何只显示我的消息

Answer 1

您可以通过创建 Guid 来做到这一点一个Nullable<Guid>并执行 null检查:

public IHttpActionResult Get(Guid? guid) {

    if(!guid.HasValue || guid.Value == Guid.Empty)
        // return your error here

    else
    //...
}