Question

我是Doctrine的新手，我开始将它用于个人项目。我正在使用laravel-doctrine库来使用laravel。

不幸的是，当我尝试订购分页查询时，我看到以下错误：

An exception occurred while executing 'SELECT DISTINCT id_0 FROM (SELECT 
t0_.id AS id_0, t0_.title AS title_1, t0_.slug AS slug_2, t0_.views AS  
views_3, t0_.replies AS replies_4, t0_.created_at AS created_at_5,  
t0_.updated_at AS updated_at_6, p1_.id AS id_7, p1_.body AS body_8,  
p1_.created_at AS created_at_9, p1_.updated_at AS updated_at_10,  
p1_.deleted_at AS deleted_at_11, c2_.id AS id_12, c2_.name AS name_13,  
c2_.slug AS slug_14, c2_.created_at AS created_at_15, c2_.updated_at AS  
updated_at_16 FROM topics t0_ LEFT JOIN posts p1_ ON t0_.id = p1_.topic_id  
LEFT JOIN categories c2_ ON t0_.category_id = c2_.id) dctrn_result ORDER BY  
created_at_5 ASC LIMIT 10 OFFSET 0':

SQLSTATE[HY000]: General error: 3065 Expression #1 of ORDER BY clause is not  
in SELECT list, references column 'dctrn_result.created_at_5' which is not  
in SELECT list; this is incompatible with DISTINCT

导致此错误的实际代码如下：

    public function findAll($results = 10, $pageName = 'page') {
        $query = $this->createQueryBuilder('t')
            ->select('t', 'f', 'c')
            ->leftJoin('t.first', 'f', 'ON')
            ->leftJoin('t.category', 'c', 'ON')
            ->orderBy('t.createdAt', 'asc')
            ->getQuery();

        return $this->paginate($query, $results, $pageName);
    }

我正在尝试选择一个主题列表，其中的类别和第一个帖子都是按主题created_at日期排序的。

我花了一些时间研究这个问题，但是到目前为止还没有弄清楚发生了什么，我还有另一种方法吗？或者我的代码是不正确的？

Answer 1

事实证明，paginate()的第四个参数导致此问题，默认为true，但将其设置为false会导致此问题重新开始。

 public function paginate(Query $query, $perPage, $pageName = 'page', $fetchJoinCollection = true)

只需将$fetchJoinCollection设为false即可。我不确定究竟为什么，但它现在有效。

Answer 2

根据这个http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/tutorials/pagination.html原则，计算正确计数的步骤为3步：

使用DISTINCT关键字执行计数查询。
使用DISTINCT执行限制子查询，以在当前页面上查找实体的所有ID。
执行WHERE IN查询以获取当前页面的所有结果。

我认为当ORDER BY子句附加在子查询之外而不是内部时会出现错误，这会产生SQL错误。在文档的底部，他们确实说设置fetchJoinCollection = false将跳过1步。这可能会解决这个问题。

我希望他们在将来的版本中解决这个问题。

Laravel Doctrine订购分页结果

2 个答案: