如何在 nHibernate 中部分投影具有多个字段的子对象

我有以下 nHibernate 查询，它根据课程 ID 选择课程，然后返回选定的字段对于初始获取的课程对象，查询执行没有问题。

MatchMode option = ... 
CourseItem courseAlias  = null;
TeacherItem teacherAlias = null;

var query = session.QueryOver<CourseItem>()
    .JoinAlias(c => c.Teacher, () => teacherAlias)
    .Where(c => c.CourseID.IsInsensitiveLike(strNumber, option))
    .SelectList(list => list
               .Select(c => c.CourseID).WithAlias(() => courseAlias.CourseID)
               .Select(c => c.IsActive).WithAlias(() => courseAlias.IsActive)
               .Select(c => c.CourseDesc).WithAlias(() => courseAlias.CourseDesc)
               .Select(c => c.Teacher).WithAlias(() => courseAlias.Teacher))
               .TransformUsing(Transformers.AliasToBean<CourseItem>())
.List<CourseItem>();

我想更进一步，查询仅返回部分教师对象，假设我只想返回 ID 和名称。因此，我将预计列表更新为如下：

var query = session.QueryOver<CourseItem>()
    .JoinAlias(c => c.Teacher, () => teacherAlias)
    .Where(c => c.CourseID.IsInsensitiveLike(strNumber, option))
    .SelectList(list => list
               .Select(c => c.CourseID).WithAlias(() => courseAlias.CourseID)
               .Select(c => c.IsActive).WithAlias(() => courseAlias.IsActive)
               .Select(c => c.CourseDesc).WithAlias(() => courseAlias.CourseDesc)
               .Select(c => c.Teacher.ID).WithAlias(() => courseAlias.Teacher.ID)
               .Select(c => c.Teacher.Name).WithAlias(() => courseAlias.Teacher.Name))
               .TransformUsing(Transformers.AliasToBean<CourseItem>())
.List<CourseItem>();

该查询不起作用，因为 nHibernate 不知道如何根据 Teacher.ID 和 Teacher.Name 进行解析。关于是否可以不获取的任何想法整个子对象返回父对象？

我已经尝试了以下查询，它有效，但这不是我完全想要的结果

var query = session.QueryOver<CourseItem>(() => courseAlias)
    .JoinAlias(() => courseAlias.Teacher, () => teacherAlias)
    .Where(() => courseAlias.CourseID.IsInsensitiveLike(strNumber, option))
    .SelectList(list => list
               .Select(() => courseAlias.CourseID)
               .Select(() => courseAlias.IsActive)
               .Select(() => courseAlias.CourseDesc)
               .Select(() => teacher.ID)
               .Select(() => teacher.Name))
    .List<object[]>();

我可以查询正确的值，但无法将其正确转换回课程/教师数据类型。

有什么想法吗？

thanks!

我们确实可以使用自定义变压器。有一个，我用它来进行非常非常深的投影（包括动态物体 -5.1.13.组件，动态组件 http://nhforge.org/doc/nh/en/index.html#mapping-declaration-component)

• DeepTransformer<TEntity> https://stackoverflow.com/a/24248309/1679310

接受它（如果需要调整它），你的最终查询可能是这样的

// just the last lines are different
var query = session.QueryOver<CourseItem>()
    .JoinAlias(c => c.Teacher, () => teacherAlias)
    .Where(c => c.CourseID.IsInsensitiveLike(strNumber, option))
    .SelectList(list => list
           .Select(c => c.CourseID).WithAlias(() => courseAlias.CourseID)
           .Select(c => c.IsActive).WithAlias(() => courseAlias.IsActive)
           .Select(c => c.CourseDesc).WithAlias(() => courseAlias.CourseDesc)

           // the native WitAlias would not work, it uses expression
           // to extract just the last property
           //.Select(c => c.Teacher.ID).WithAlias(() => courseAlias.Teacher.ID)
           //.Select(c => c.Teacher.Name).WithAlias(() => courseAlias.Teacher.Name))

           // so we can use this way to pass the deep alias
          .Select(Projections.Property(() => teacherAlias.ID).As("Teacher.ID"))
          .Select(Projections.Property(() => teacherAlias.Name).As("Teacher.Name"))

           // instead of this
           // .TransformUsing(Transformers.AliasToBean<CourseItem>())
           // use this
           .TransformUsing(new DeepTransformer<CourseItem>())

如果您的别名确实与属性名称匹配，则该转换器将构建对象树......