grails - 默认情况下，标准使用 “inner join”而不是 “left join”方法使我的查询不按我计划的方式工作

Question

问题是:在此特定示例中，如何使GORM生成左联接而不是内联接？

测试平台:

给定A，B和C类:

class A{
    B someObject
}

class B{
    C importantObject
}

class C{
    boolean interestingFlag
}

我想列出A类的所有元素:

他们的B.C对象为null或

他们的B.C对象有趣的标志值是假的

到目前为止我尝试过的是:

此方法将生成A的正确列表，其中B.C为空(条件2被注释掉)，或者生成A的正确列表，其中B.C.interestingFlag = false(无论条件1是否被注释掉)。当两个条件都取消注释时，它仅返回A.B.C.interestingFlag = false(A.B.C = null条件被忽略)的元素列表。

// approach 1 (conditional 1 is ignored)
def result = A.withCriteria{
    someObject{
        or{
            isNull('importantObject') // conditional 1, works well when conditional 2 is commented out
            importantObject{
                eq('interestingFlag', false) // conditional 2, works well alone, discards conditional 1 when both of them are uncommented
            }
        }  
    } 
}

编辑:
根据评论中的要求，我粘贴了一个休眠生成的SQL:

Hibernate: select this_.id as id1_2_, this_.version as version1_2_, 
this_.some_object_id as some3_1_2_, someobject1_.id as id2_0_, 
someobject1_.version as version2_0_, someobject1_.important_object_id as 
important3_2_0_, importanto2_.id as id0_1_, importanto2_.version as version0_1_, 
importanto2_.interesting_flag as interest3_0_1_ from a this_ 
inner join b someobject1_ on this_.some_object_id=someobject1_.id 
inner join c importanto2_ on someobject1_.important_object_id=importanto2_.id 
where ((someobject1_.important_object_id is null or (importanto2_.interesting_flag=?)))

当我直接将其复制并粘贴到pgAdmin查询工具中时，做了一些更改(将内部联接更改为左联接，并提供了趣味的Flag =“false”参数)，一切都按我的意愿工作(我得到了ABC = null和ABCimportantFlag =错误的对象)

Hibernate: select this_.id as id1_2_, this_.version as version1_2_, 
this_.some_object_id as some3_1_2_, someobject1_.id as id2_0_, 
someobject1_.version as version2_0_, someobject1_.important_object_id as 
important3_2_0_, importanto2_.id as id0_1_, importanto2_.version as version0_1_, 
importanto2_.interesting_flag as interest3_0_1_ from a this_ 
left join b someobject1_ on this_.some_object_id=someobject1_.id 
left join c importanto2_ on someobject1_.important_object_id=importanto2_.id 
where ((someobject1_.important_object_id is null or (importanto2_.interesting_flag=false)))

Answer 1

经过测试的工作解决方案:

    def result = A.withCriteria{
        createAlias('someObject', 'so', CriteriaSpecification.LEFT_JOIN)
        createAlias('so.importantObject', 'imp', CriteriaSpecification.LEFT_JOIN)
        or {
            isNull('so.importantObject')
            eq('imp.interestingFlag', false)
        } 

    }

注释中建议的解决方案更新:

    def result = A.withCriteria{
        createAlias('someObject', 'so', JoinType.LEFT_OUTER_JOIN)
        createAlias('so.importantObject', 'imp', JoinType.LEFT_OUTER_JOIN)
        or {
            isNull('so.importantObject')
            eq('imp.interestingFlag', false)
        } 

    }