Doctrine2 错误 "Expected known function, got 'COUNT'" when in order by clause

Question

我正在使用 doctrine2

我尝试通过售出的门票数量

获得订购的"Events"数量

$manager = $this->getDoctrine()->getManager();
$builder = $manager->createQueryBuilder();

return $builder
    ->select('e')
    ->from('AppBundle:Event', 'e')
    ->leftJoin('e.tickets', 't')
    ->orderBy('COUNT(t)')
    ->groupBy('e.id')
    ->setMaxResults(10)
    ->getQuery()
    ->getResult()
;

这会产生错误

[Syntax Error] line 0, col 80: Error: Expected known function, got 'COUNT'

用下面的DQL产生

QueryException: SELECT e FROM AppBundle:Event e LEFT JOIN e.tickets t GROUP BY e.id ORDER BY COUNT(t.id) ASC

但是，如果我将 COUNT 放在 SELECT 部分，它确实可以正常工作（但是我必须做额外的处理以删除 SELECT 不需要的字段）

return $builder
    ->select('e')
    ->from('AppBundle:Event', 'e')
    ->addSelect('COUNT(t) AS nbrTicketsSold')
    ->leftJoin('e.t', 't')
    ->orderBy('nbrTicketsSold')
    ->groupBy('e.id')
    ->setMaxResults(10)
    ->getQuery()
    ->getResult()
;

在 ORDER BY 子句中使用 COUNT 是否是 DQL 的已知限制？

Answer 1

学说文档中的 EBNF 实际上说明了 ORDER BY 子句中的可能性：

OrderByClause       ::= "ORDER" "BY" OrderByItem {"," OrderByItem}*
OrderByItem ::= (SimpleArithmeticExpression | SingleValuedPathExpression | ScalarExpression | ResultVariable | FunctionDeclaration) ["ASC" | "DESC"]

With FunctionDeclaration 包含这些功能：

函数返回数值： LENGTH LOCATE ABS SQRT MOD SIZE DATE_DIFF BIT_AND BIT_OR

函数返回日期时间： CURRENT_DATE CURRENT_TIME CURRENT_TIMESTAMP DATE_ADD DATE_SUB

函数返回字符串： CONCAT SUBSTRING TRIM LOWER UPPER IDENTITY

COUNT 是 AggregateExpression 组 (Link) 的一部分，这些在 ORDER BY 子句中是不允许的。

此外，文档实际上还有一个进一步使用 AS HIDDEN 按计数排序的示例：

Retrieve user entities with Arithmetic Expression in ORDER clause, using the HIDDEN keyword:
$query = $em->createQuery('SELECT u, u.posts_count + u.likes_count AS HIDDEN score FROM CmsUser u ORDER BY score');
$users = $query->getResult(); // array of User objects

Doctrine2 错误 "Expected known function, got 'COUNT'" when in order by clause

Doctrine2 error "Expected known function, got 'COUNT'" when in order by clause

php

dql

symfony

doctrine-orm