linq - 如何在NHibernate中查询动态属性？

Question

我有这个问题。我有一堂这样的课:

public class WfStep
{
    private readonly IDictionary properties = new Hashtable();

    public virtual Guid Id { get; private set; }
    public virtual string Name { get; set; }
    public virtual dynamic Properties { get { return new HashtableDynamicObject(properties); } }

及其映射文件如下:

<class name="ConsoleApplication4.WfStep" table="WFSteps">

<id name="Id">
  <generator class="guid"/>
</id>
<property name="Name" />

<map name="Properties" table="WFSteps_Properties" access="field.lowercase">
  <key column="StepId" />
  <index column="PropertyName" type="System.String"/>
  <composite-element class="ConsoleApplication4.ValueItem, ConsoleApplication4">
    <property name="Value" type="System.String"/>
    <property name="ValueType" type="System.String"/>
  </composite-element>
</map>   

这个例子移植自: Ayende Support dynamic fields with NHibernate and .NET 4.0

然后我将一个对象保存到数据库，如下所示:即。

var step = new WfStep { Name = "John" };
var property = new ValueItem() { Value = DateTime.Now, ValueType = "System.DateTime" };
step.Properties["DateProperty"] = property ;

Session.Save(step);

现在我想返回所有将 DateProperty 设置为 2010 年的 WFStep，即:

var Session.Query<WfStep>().Where(x=>x.Properties.DateProperty.Year == 2010);

它抛出一个错误:

An expression tree may not contain a dynamic operation

如何查询具有动态属性的此类类型？

Answer 1

您可以对映射为 map 或列表的集合建立索引。尝试以下 hql

from WfStep s
where s.Properties["DateProperty"] = "2010"