如何在 Grails HQL 语句中排序

Question

我有这样的关系：

class Foo {
    static hasMany = [bars: Bar, things: Thing]
}

class Bar {
    // Has nothing to tie it back to Foo or Thing
}

class Thing {
    // Has nothing to tie it back to Foo or Bar
}

我有以下带有以下参数的查询，其中大部分用于flexigrid的分页。此查询通过Foo 获取与Bar 的特定实例相关联的所有Thing 实例。因此，如果我的Bar 实例是Bar1，那么我的查询会返回Thing1 和Thing2：

def obj = Bar.get( 1 ) // Get Bar1
def max = params.int( "max" ) ?: 100 // Default max returned results is 100 unless otherwise specified
def offset = params.int( "offset" ) ?: 0 // Default offset is 0 unless otherwise specified
def sortname = params.sortname ?: "id" // Default is id, but could be any member of Thing that is not a "hasMany"
def sortorder = params.sortorder ?: "ASC" // Default is ASC, but could be DESC

def namedParams = [ obj: obj, max: max, offset: offset ]

Thing.executeQuery( "SELECT DISTINCT f.things FROM Foo f INNER JOIN f.things things INNER JOIN f.bars bars WHERE bars =:obj ORDER BY ${sortname} ${sortorder}", namedParams )

Hibernate 不允许使用命名参数来指定ORDER BY 子句，所以我只是插入了字符串。问题是结果没有按照我指定的顺序排列。使用ORDER BY id 时，Grails 告诉我id 不明确。

知道变量sortname 将始终是Thing 的成员，我该如何指定要排序的内容？

我尝试过的一些事情：

ORDER BY Thing.id // Fail
ORDER BY f.things.id // Fail
ORDER BY things.id // FAIL!

Answer 1

查询应该是：

SELECT DISTINCT thing FROM Foo f 
INNER JOIN f.things thing 
INNER JOIN f.bars bar 
WHERE bar = :obj 
ORDER BY thing.id

即您应该在 select 子句中使用实体的别名而不是其路径，并在 order by 子句中使用相同的别名。