NHibernate QueryOver 与 SelectList

Question

我有多个查询针对一个 table。由于并非所有 columns/properties 都是必需的，因此我在 select 列表的帮助下指定了列。以下面的方法为例。这个方法有效

public IEnumerable<ResultDto> GetEntityAsDto(eStatusBinderProduktion fromState, eStatusBinderProduktion toState)
{
    EntityClass entityAlias = null;
    ResultDto resultAlias = null;

    var query = Session.QueryOver<EntityClass>(() => entityAlias)
      .Where(() => entityAlias.ProduktionStatus >= (byte)fromState)
      .And(() => entityAlias.ProduktionStatus <= (byte)toState);

    query.SelectList(list => list
         .Select(() => entityAlias.PrimaryID).WithAlias(() => resultAlias.PrimaryID)
         .Select(() => entityAlias.SecondaryID).WithAlias(() => resultAlias.SecondaryID)
         );

    return query.TransformUsing(Transformers.AliasToBean<ResultDto>())
          .List<ResultDto>();
}

因为我需要在多个方法中定义 SelectList，所以我尝试将 SelectList 移动到一个单独的方法中。

以下代码无效，NHibernate 抛出异常

NHibernate.QueryException: 'could not resolve property: entity.PrimaryID of: MyProjectNamespace.DAL.Interfaces.Entities.EntityClass' "

public IEnumerable<ResultDto> GetEntityAsDto(eStatusBinderProduktion fromState, eStatusBinderProduktion toState)
{
    EntityClass entityAlias = null;
    ResultDto resultAlias = null;

    var query = Session.QueryOver<EntityClass>(() => entityAlias)
      .Where(() => entityAlias.ProduktionStatus >= (byte)fromState)
      .And(() => entityAlias.ProduktionStatus <= (byte)toState);

    MapPropertiesOfEntityToResult(entityAlias, resultAlias, query);

    return query.TransformUsing(Transformers.AliasToBean<ResultDto>())
          .List<ResultDto>();
}

private void MapPropertiesOfEntityToResult(EntityClass entity, ResultDto resultAlias, IQueryOver<EntityClass, EntityClass> query)
{
  query.SelectList(list => list
   .Select(() => entity.PrimaryID).WithAlias(() => resultAlias.PrimaryID)
   .Select(() => entity.SecondaryID).WithAlias(() => resultAlias.SecondaryID)
    );
}

附加信息：
- 映射正确
- table填充测试数据

Answer 1

我们不需要别名来填充 SelectList。我们可以从 IQueryOver<TRoot,TSubType> 附带的类型参数中获益：

//private void MapPropertiesOfEntityToResult(EntityClass entity
//   , ResultDto resultAlias, IQueryOver<EntityClass, EntityClass> query)
private void MapPropertiesOfEntityToResult( // no need for entity
      ResultDto resultAlias, IQueryOver<EntityClass, EntityClass> query)
{
  query.SelectList(list => list
   //.Select(() => entity.PrimaryID).WithAlias(() => resultAlias.PrimaryID)
   //.Select(() => entity.SecondaryID).WithAlias(() => resultAlias.SecondaryID)
   .Select(entity => entity.PrimaryID).WithAlias(() => resultAlias.PrimaryID)
   .Select(entity => entity.SecondaryID).WithAlias(() => resultAlias.SecondaryID)
    );
}

entity 现在是传递的 Function 的参数，其类型来自 IQueryOver 定义

NHibernate QueryOver 与 SelectList

NHibernate QueryOver with SelectList

c#

nhibernate

orm

projection

queryover