c# – 为什么导航有时会返回null？

public class Indicator
{
    public long IndicatorID { get; set; }
    public string Name { get; set; }
    public int MaxPoint { get; set; }
    public string Comment { get; set; }
    public DateTime DateChanged { get; set; }
    public DateTime DateCreated { get; set; }

    public virtual IList<CalculationType> CalculationTypes { get; set; }
}

public class CalculationType
{
    public long CalculationTypeID { get; set; }
    public string UnitName { get; set; }
    public int Point { get; set; }
    public DateTime DateCreated { get; set; }
    public DateTime DateChanged { get; set; }

    public virtual Indicator Indicator { get; set; }
}

我有数据库工厂

public class DatabaseFactory
{
    private StankinQuestionnaireEntities dataContext;
    public StankinQuestionnaireEntities Get()
    {
        return dataContext ?? (dataContext = new StankinQuestionnaireEntities());
    }
}

和属性,指的是databaseFactory

protected StankinQuestionnaireEntities DataContext
{
    get { return dataContext ?? (dataContext = DatabaseFactory.Get()); }
}

我使用Autofac和regiser DatabaseFactory

builder.RegisterType<DatabaseFactory>().As<IDatabaseFactory>().InstancePerRequest();

在我的存储库中,我尝试以两种方式从导航属性获取数据

第一行工作正常(CalculationType包含一个元素)

但第二行在属性CalculationType上返回null

为什么？

UPDATE
我发现如果删除“.InstancePerRequest()”行,一切正常.但我不适合这个.

UPDATE2由于某种原因,如果没有创建Proxy类