创建"在哪里"HQL查询

Question

我在编写使用"where in"子句的HQL查询时遇到问题.

简化的类看起来像这样:

class Parent
{
    public virtual Int64 Id { get; private set; }
    public virtual string Name { get; private set; }
}

class Child
{
    public virtual Int64 Id { get; private set; }
    public virtual string Name { get; private set; }
    public virtual Parent Parent { get; private set; }
}

使用如下定义的映射:

class ParentMap : ClassMap<Parent>
{
    Id(x => x.Id);
    Map(x => x.Name);
}

class ChildMap : ClassMap<Child>
{
    Id(x => x.Id);
    Map(x => x.Name);
    References(x => x.Parent);
}

我想获取Child属于某些Parent项目的实例,因此我编写了以下代码:

// get children for several parents (a flattened list)
IEnumerable<Parent> parents = GetParents();

// use hql
IQuery q = Session.CreateQuery("from Child as c where c.Parent in (:parents)");
q.SetParameter("parents", parents);

但问题是,我得到以下例外q.SetParameter:

Test method Can_get_children_for_many_parents threw exception:
  NHibernate.PropertyAccessException:
  Exception occurred getter of Some.Namespace.Parent.Id 
  ---> System.Reflection.TargetException: Object does not match target type.

[编辑]

我尝试使用q.SetParameter("parents", parents.Select(p => p.Id);,但我得到了同样的例外.

Answer 1

试试这样的事情:

q.SetParameterList("parents", parents.ToList());