Question

我还在学习NHibernate，我想知道是否有人可以帮助我将以下标准翻译成QueryOver等效标准。

我认为我已经掌握了基础知识，但在查询子集合并添加别名时我有点迷失。发布的条件查询确实返回了预期的数据，但我不确定我对标准格式的所有神奇字符串的舒适程度。

return Session.CreateCriteria<Person>()
    .Add(Restrictions.Eq("FirstName", firstName))
    .Add(Restrictions.Eq("LastName", lastName))
    .CreateCriteria("PartyContactMechanisms")
    .CreateAlias("ContactMechanism", "c")
    .Add(Restrictions.Eq("c.ElectronicAddressString", emailAddress))
    .UniqueResult<Person>();

修改我能够使用以下QueryOver返回所需的结果。我以为我会发布解决方案，以防其他人帮忙。任何有关改进此代码的建议也是受欢迎的。

Person personAlias = null;
        ElectronicAddress emailAlias = null;
        PartyContactMechanism partyContactMechAlias = null;

        return Session.QueryOver(() => personAlias)
            .Where(p => p.FirstName == firstName)
            .And(p => p.LastName == lastName)
            .JoinQueryOver(() => personAlias.PartyContactMechanisms, () => partyContactMechAlias)
            .JoinAlias(() => partyContactMechAlias.ContactMechanism, () => emailAlias)
            .Where(() => emailAlias.ElectronicAddressString == emailAddress)
            .SingleOrDefault<Person>();

Answer 1

看起来像这样：

// these are aliases, which we can/will use later, 
// to have a fully-type access to all properties
Person person = null;
PartyContactMechanism partyContactMechanisms = null;
ContactMechanism contactMechanism = null;

// search params
var firstName = ..;
var lastName  = ..;
var emailAddress = ..;

var query = session.QueryOver<Person>(() => person)
    // the WHERE
    .Where(() => person.FirstName == firstName)
    // the And() is just more fluent eq of Where()
    .And(() => person.LastName == lastName)
    // this collection we will join as criteria
    .JoinQueryOver(() => person.PartyContactMechanism, () => partyContactMechanisms)
    // its property as alias
    .JoinAlias(() => partyContactMechanisms.ContactMechanism, () => contactMechanism )
    // final filter 
    .Where(() => contactMechanism.Code == emailAddress)
    // just one result
    .Take(1)
    ;


var uniqueResult = query
    .List<Person>()
    .SingleOrDefault();

如需了解更多信息，请在此深入了解：

Chapter 16. QueryOver Queries
或此处

注意：还要检查子查询，因为查询“集合”时这些要好得多。只需搜索它们......并将其用作子选择WHERE parentId IN (SELECT parentId FROM ChildTable...

查询的NHibernate标准

1 个答案: