如何编写包含多个联接的条件查询 [英] How to a write a Criteria query with multiple joins involved

问题描述

我正在尝试使用Criteria API对以下HQL查询进行编码:

I'm trying to code the following HQL query using the Criteria API:

var userList = _session
                .CreateQuery("select u from User u where u.Role.ID=3 and u.Customer.ID=:cID")
                .SetInt32("cID", 1)
                .List<User>();

(3个NHibernate对象:用户(ID，名称，角色，客户)，角色(ID，名称)和客户(ID，名称).

(3 NHibernate objects : User(ID, Name, Role, Customer), Role(ID, Name) and Customer(ID, Name).

我尝试了以下操作，但由于NHibernate试图找到与某个角色相关联的客户而无法使用:

I tried the following but it doesn't work because NHibernate tries to find a Customer associated with a Role:

var userList = _session
            .CreateCriteria(typeof(User))
            .CreateCriteria("Role")
            .Add(Restrictions.Eq("ID", 3) )
            .CreateCriteria("Customer")
            .Add(Restrictions.Eq("ID", 1) )
            .List<User>();

还有其他可行的方法吗?

Any other way (that works!) of doing it?

推荐答案

您可以使用别名

var userList = _session
        .CreateCriteria(typeof(User), "u")
        .CreateAlias("u.Role", "r")
        .Add(Restrictions.Eq("r.ID", 3) )
        .CreateAlias("u.Customer", "c")
        .Add(Restrictions.Eq("c.ID", 1) )
        .List<User>();

希望有帮助

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