linq - 无法解析属性(复杂属性)

Question

我有一个带有NHibernate的asp.net mvc应用程序，我不知道如何解决查询某些数据的问题。我有这样的疑问:

// create query
var query = session.QueryOVer<Laudo>().Fetch(x => x.Equipament).Eager;

// add some filters
if (idEquipament.HasValue) 
  query = query.And(x => x.Equipament.Id == idEquipament.Value);

//I got the error here...
if (idCompany.HasValue)
  query = query.And(x => x.Equipament.Company.Id == idCompany.Value);

当我尝试执行此查询时，出现以下消息的异常: “无法解析属性:Equipament.Company.Id of:DomainModel.Laudo”

我可以做什么来解决这个问题？ 谢谢

Answer 1

您不能像这样使用其他实体属性。 NHibernate 期望表达式能够被计算为当前实体的属性。您需要使用JoinQueryOver或JoinAlias加入另一个实体，然后执行 where 。

使用JoinQueryOver:

// ...
query = query.JoinQueryOver(x => x.Equipment)
    .JoinQueryOver(x => x.Company)
    .Where(c => c.Id == idCompany.Value);

使用JoinAlias:

Equipment equipment = null;
Company company = null;

// ...
query = query.JoinAlias(x => x.Equipment, () => equipment)
    .JoinAlias(() => equipment.Company, () => company)
    .Where(() => company.Id == idCompany.Value);

更多信息:
What is the difference between JoinQueryOver and JoinAlias?
What can be used as a NHibernate QueryOver alias?
Complex nHibernate QueryOver expression