按键查询时，SingleResult <T>在Web API中不可序列化

Question

尝试使用主键CourseID针对odata web.api查找单个记录，方法如下：

var editedcourse = container.Courses.Where(c => c.CourseID == ID).SingleOrDefault();

这是错误的：

    <m:innererror>
    <m:message>The 'ObjectContent`1' type failed to serialize the response body for content type 'application/atom+xml; charset=utf-8'.</m:message>
    <m:type>System.InvalidOperationException</m:type>
    <m:stacktrace></m:stacktrace>
    <m:internalexception>
      <m:message>'SingleResult`1' cannot be serialized using the ODataMediaTypeFormatter.</m:message>
      <m:type>System.Runtime.Serialization.SerializationException</m:type>

Answer 1

默认情况下，web.api控制器方法不可查询，因此客户端失败。添加了注释以修复： [Queryable(AllowedOrderByProperties = "Id")]