我有一个简单的枚举，我试图将其包含在我的GraphQL类型中，并收到以下错误：
无法隐式派生父类型“NewsItemType”上Field：“Category”的GraphQL类型。
-------------------无法隐式派生父类型“NewsItemType”上Field：“Category”的GraphQL类型。

• 类型：NewsType不能有效地强制为GraphQL类型参数名：type
  我的简单枚举看起来像：

public enum NewsType
{
    General = 0,
    Business = 1,
    Entertainment = 2,
    Sports = 3,
    Technology = 4
}

字符串
它包含在GraphQL ObjectGraphType中：

public class NewsItemType : ObjectGraphType<NewsItemViewModel>
{
    public NewsItemType()
    {
        Field(x => x.Id).Description("Id of a news item.");
        Field(x => x.Title).Description("Title of a new item.");
        Field(x => x.Description).Description("Description of a news item.");
        Field(x => x.Author).Description("Author of a news item.");
        Field(x => x.Url).Description("URI location of the news item");
        Field(x => x.ImageUrl).Description("URI location of the image for the news item");
        Field(x => x.PublishDate).Description("Date the news item was published");
        Field(x => x.Category).Description("Category of the news item.");
    }
}

型
最后是GraphQL类型所基于的视图模型：

public class NewsItemViewModel : ViewModelBase
{
    public string Title { get; set; }
    public string Author { get; set; }
    public string Description { get; set; }
    public string Url { get; set; }
    public string ImageUrl { get; set; }
    public DateTime PublishDate { get; set; }
    public NewsType Category { get; set; }
}

型
我在这里做错了什么，我如何克服它？
编辑：我的查询包含以下内容：

Field<ListGraphType<NewsItemType>>(
            name: "newsItems",
            arguments: new QueryArguments(
                new QueryArgument<IntGraphType>() { Name = "count" },
                new QueryArgument<IntGraphType>() { Name = "category" }),
            resolve: context =>
            {
                var count = context.GetArgument<int?>("count");
                var category = context.GetArgument<int>("category");
                var newsType = (NewsType)category;

                if (count.HasValue)
                {
                    return newsItemService.GetMostRecent(newsType, count.Value);
                }
                else
                {
                    return newsItemService.GetMostRecent(newsType);
                }
            }
        )

型