umbraco - 如何在 UmbracoApiController 中创建继承 RenderModel 的模型实例？

Question

我正在使用 Umbraco CMS。我有以下模型:

 public class LoyaltyPromo : RenderModel
    {
        public LoyaltyPromo(IPublishedContent content)
            : base(content)
        {
        }
        //properties removed for brevity
    }

我想在 UmbracoApiController 中使用这个模型。所以我这样做:

    public class PromoServiceController : UmbracoApiController
        {
            public async Task<object> GetAll()
            {

                var umbracoHelper = new UmbracoHelper(UmbracoContext.Current);
                IPublishedContent content = umbracoHelper.TypedContent(1050);
                var list = new List<LoyaltyPromo>();
                list.Add(new LoyaltyPromo(content));
                return list;

            }
        }

不幸的是它不起作用，我得到了NullReferenceException:

An error has occurred. Object reference not set to an instance of an object. System.NullReferenceException at Umbraco.Web.Models.RenderModel..ctor(IPublishedContent content) at LoyaltyOps.Models.LoyaltyPromo..ctor(IPublishedContent content) in C:\Users\mkallingal\documents\visual studio 2015\Projects\LoyaltyOps\LoyaltyOps.Models\LoyaltyPromo.cs:line 13 at LoyaltyOps.Controllers.PromoServiceController.d__0.MoveNext() in C:\Users\mkallingal\documents\visual studio 2015\Projects\LoyaltyOps\LoyaltyOps\Controllers\PromoServiceController.cs:line 32 --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Threading.Tasks.TaskHelpersExtensions.d__3`1.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Controllers.ApiControllerActionInvoker.d__0.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Controllers.ActionFilterResult.d__2.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Dispatcher.HttpControllerDispatcher.d__1.MoveNext()

我该如何解决这个问题？

Answer 1

您的问题是 RenderModel 不适合在 WebAPI 中使用，它根本没有关于前端页面的上下文。在内部，RenderModel 依赖于正确设置的 UmbracoContext 的 PublishedContentRequest 属性，而 WebAPI 不会发生这种情况。

如果您确实需要将模型建立在 RenderModel 的基础上，请使用替代构造函数:

RenderModel(IPublishedContent 内容，CultureInfo 文化)

并传入文化和内容 - 这将绕过设置 PublishedContentRequest 的需要，但您可能会进一步遇到其他问题。

更好的方法是创建一个完全不依赖于 RenderModel 的 View 模型。由于 WebAPI 通常会将模型序列化为 JSON，因此模型越轻越好。

另一件事 - 您的 GetAll() 列表根本不返回 - 我假设您的实际方法中没有进行额外的处理，需要您的模型基于 RenderModel ，并且您只是返回列表？