需要帮助优化使用Restrictions.In(..)的NHibernate条件查询
需要帮助优化使用Restrictions.In(..)的NHibernate条件查询
提问于 2010-05-08 05:22:27
我正在尝试找出是否有一种方法可以通过子查询或其他更优化的方法严格使用Criteria和DetachedCriteria来完成以下操作。NameGuidDto只不过是一个具有string和Guid属性的轻量级对象。
public IList<NameGuidDto> GetByManager(Employee manager)
{
// First, grab all of the Customers where the employee is a backup manager.
// Access customers that are primarily managed via manager.ManagedCustomers.
// I need this list to pass to Restrictions.In(..) below, but can I do it better?
Guid[] customerIds = new Guid[manager.BackedCustomers.Count];
int count = 0;
foreach (Customer customer in manager.BackedCustomers)
{
customerIds[count++] = customer.Id;
}
ICriteria criteria = Session.CreateCriteria(typeof(Customer))
.Add(Restrictions.Disjunction()
.Add(Restrictions.Eq("Manager", manager))
.Add(Restrictions.In("Id", customerIds)))
.SetProjection(Projections.ProjectionList()
.Add(Projections.Property("Name"), "Name")
.Add(Projections.Property("Id"), "Guid"))
// Transform results to NameGuidDto
criteria.SetResultTransformer(Transformers.AliasToBean(typeof(NameGuidDto)));
return criteria.List<NameGuidDto>();
}回答 1
Stack Overflow用户
回答已采纳
发布于 2010-05-10 22:35:51
return Session.CreateCriteria<Customer>()
.CreateAlias("BackupManagers", "bm", LeftOuterJoin)
.Add(Restrictions.Disjunction()
.Add(Restrictions.Eq("Manager", manager))
.Add(Restrictions.Eq("bm.Id", manager.Id)))
.SetProjection(Projections.Distinct(Projections.ProjectionList()
.Add(Projections.Property("Name"), "Name")
.Add(Projections.Property("Id"), "Guid")))
.SetResultTransformer(Transformers.AliasToBean(typeof(NameGuidDto)))
.List<NameGuidDto>();我在其中添加了一个distinct，因为我不确定是否可以让backup和primary是同一个人。
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原文链接：
https://stackoverflow.com/questions/2791775
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