当我使用虚拟属性时，WCF Rest GET不返回任何内容

这是我第一次开发Rest WCF服务。

这就是我所做的让数据库中的所有用户：

namespace MyCompanyWCFService
{
    [ServiceContract]
    public interface IMyCompanyService
    {
        [WebGet(UriTemplate = "/users",
                BodyStyle=WebMessageBodyStyle.Bare,
                ResponseFormat=WebMessageFormat.Json)]
        [OperationContract]
        List<User> GetAllUsers();
        [OperationContract]
        [WebGet(ResponseFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.Bare)]
        MyClass DoWork();
    }
}

实施：

namespace MyCompanyWCFService
{
    public class MyCompanyService : IMyCompanyService
    {
        public List<User> GetAllUsers()
        {
            List<User> usersList = null;
            using (var context = new MyCompanyContext())
            {
                usersList = context.Users.ToList();
            }
            return usersList;
        }
        public MyClass DoWork()
        {
            var returnObject = new MyClass
            {
                Id = 1,
                IHaveNoDataMemberAttribute = "Meaningless",
                Name = "Satchmo",
                NoPublicGet = "Hello world!",
                InternalProperty = 155
            };
            return returnObject;
        }
    }
}

User型号类别：

namespace MyCompanyModel
{
    [DataContract]
    public class User
    {
        [DataMember]
        public int UserId { get; set; }
        [DataMember]
        public string Name { get; set; }
        [DataMember]
        public int Age { get; set; }
        [DataMember]
        public string City { get; set; }
        [DataMember]
        public string Country { get; set; }
        [DataMember]
        public string Email { get; set; }
        [DataMember]
        public string InterestIn { get; set; }

        [DataMember]
        public virtual ICollection<User> Friends { get; set; }
        [DataMember]
        public virtual ICollection<User> FromWhomIsFriend { get; set; }
        [DataMember]
        public virtual ICollection<Activity> WantsToDo { get; set; }
        [DataMember]
        public virtual ICollection<Message> MessagesSent { get; set; }
        [DataMember]
        public virtual ICollection<Message> MessagesReceived { get; set; }
        public override string ToString()
        {
            string output = string.Empty;
            output = String.Format("UserId: {0}, Name: {1}, Age: {2}, City: {3}, " +
                "Country: {4}, Email: {5}, InterestIn: {6}",
                UserId, Name, Age, City, Country, Email, InterestIn);
            return output;
        }
    }
}

MyClass:

namespace MyCompanyWCFService
{
    [DataContract]
    public class MyClass
    {
        [DataMember]
        public int Id { get; set; }
        [DataMember]
        public string Name { get; set; }
        public string IHaveNoDataMemberAttribute { get; set; }
        [DataMember]
        public string NoPublicGet { private get; set; }
        [DataMember]
        internal ushort InternalProperty { get; set; }
    }
}

和web.config:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
    <section name="entityFramework"
             type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=4.4.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"
             requirePermission="false" />
  </configSections>
  <system.web>
    <compilation debug="true" targetFramework="4.0" />
  </system.web>
  <system.serviceModel>
    <services>
      <service name="MyCompanyWCFService.MyCompanyService">
        <endpoint address="" 
                  contract="MyCompanyWCFService.IMyCompanyService"
                  behaviorConfiguration="restfulBehavior"
                  bindingConfiguration=""
                  binding="webHttpBinding" />
      </service>
    </services>
    <behaviors>
      <endpointBehaviors>
        <behavior name="restfulBehavior">
          <webHttp />
        </behavior>
      </endpointBehaviors>
      <serviceBehaviors>
        <behavior>
          <serviceMetadata httpGetEnabled="true" />
          <serviceDebug includeExceptionDetailInFaults="false" />
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <serviceHostingEnvironment multipleSiteBindingsEnabled="true" />
  </system.serviceModel>
  <system.webServer>
    <modules runAllManagedModulesForAllRequests="true" />
  </system.webServer>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="v11.0" />
      </parameters>
    </defaultConnectionFactory>
  </entityFramework>
  <connectionStrings>
    <add name="MyCompanyContext"
          providerName="System.Data.SqlClient"
          connectionString="Server=.'SQLEXPRESS;Database=MyCompany;Integrated Security=True;MultipleActiveResultSets=True"/>
  </connectionStrings>
</configuration>

但是，当我在网络浏览器上设置这个URI http://localhost:7342/MyCompanyService.svc/users时，我什么也得不到。我还用PostMan Chrome扩展进行了测试，但一无所获。

调试代码context.Users.ToList();返回三个用户。

但是，如果我这样做，http://localhost:7342/MyCompanyService.svc/DoWork，它运行得很好：

{"Id":1,"InternalProperty":155,"Name":"Satchmo","NoPublicGet":"Hello world!"}

问题出在public virtual属性上。如果我删除virtual，它可以工作，但我需要virtual来延迟加载这些导航属性。

如何解决此问题

    public List<User> GetAllUsers()
    {
        List<User> usersList = null;
        using (var context = new AdnLineContext())
        {
            context.Configuration.ProxyCreationEnabled = false;
            usersList = context.Users.ToList();
        }
        return usersList;
    }