asp.net-mvc - Web API错误: The 'ObjectContent` 1' type failed to serialize the response body for content type

Question

我在尝试使用 Web API Controller 时收到此错误。

Web API Error: The 'ObjectContent`1' type failed to serialize the response body for content type

我的 Controller 中的代码如下

public IEnumerable<Student> GetAllStudents()
    {
        var allstudents = unitOfWork.StudentRepository.Get(includeProperties: "Groups");


        return allstudents;
    }

    public Student GetStudentByID(Guid id)
    {
        return unitOfWork.StudentRepository.GetByID(id);
    }

我的“学生”类(class)如下

public partial class Student
{
    public Student()
    {
        this.Groups = new HashSet<Group>();
    }

    public System.Guid StudentID { get; set; }
    public string Surname { get; set; }
    public string FirstName { get; set; }
    public byte[] Timestamp { get; set; }

    public virtual Course Course { get; set; }
    public virtual ICollection<Group> Groups { get; set; }
}

两种方法都会导致相同的错误。

我内心的异常如下

Type 'System.Data.Entity.DynamicProxies.Student_4C97D068E1AD0BA62C3C6E441601FFB7418AD2D635F7F1C14B64F4B2BE32DF9A' with data contract name 'Student_4C97D068E1AD0BA62C3C6E441601FFB7418AD2D635F7F1C14B64F4B2BE32DF9A:http://schemas.datacontract.org/2004/07/System.Data.Entity.DynamicProxies' is not expected. Consider using a DataContractResolver or add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to DataContractSerializer.

我感觉我需要使用 KnownType 属性，但我不太确定如何实现它。

如有任何帮助，我们将不胜感激

Answer 1

如果您不需要代理类 (System.Data.Entity.DynamicProxies.Student_4C97D068E1A...) 提供的延迟加载导航属性，您可以通过设置禁用它们的生成:

unitOfWork.Configuration.ProxyCreationEnabled = false;

如果需要代理类怎么办 another question .

<小时/>

点击这些链接可以很好地了解延迟加载和代理:

• Loading Related Entities
• Working with Proxies
• Should I enable or disable dynamic proxies

我通常默认禁用延迟加载和代理，并在需要它们的特定代码块中启用其中之一或两者。